AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/10/26 11:45	flow	patch-triage	6m Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "KMSANReasoning": "", "NeedsKMSAN": false, "Reasoning": "The patch modifies rpmsg_eptdev_ioctl() in drivers/rpmsg/rpmsg_char.c to hold eptdev-\u003eept_lock and check for NULL eptdev-\u003eept during RPMSG_SET_INCOMING_FLOWCONTROL ioctls. However, RPMsg (Remote Processor Messaging) devices are exclusively provided by remote coprocessor subsystems on embedded SoCs (such as Qualcomm GLINK/SMD, MediaTek SCP, or remoteproc virtio devices). On the target architecture (amd64), no RPMsg hardware or virtual devices exist or are emulated in standard QEMU/GCE environments. Because no underlying rpmsg_device can be registered, neither /dev/rpmsg_ctrl* nor /dev/rpmsg* character devices can be instantiated or opened, rendering rpmsg_eptdev_ioctl structurally unreachable.", "WorthFuzzing": false }
1/1	2026/10/26 11:45	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit ef9f789b3f5fe7743026f0349064fb807a2de3c9\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Mon Oct 26 11:45:00 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c\nindex 550fda217da45..49c0784fec2e8 100644\n--- a/drivers/rpmsg/rpmsg_char.c\n+++ b/drivers/rpmsg/rpmsg_char.c\n@@ -343,7 +343,15 @@ static long rpmsg_eptdev_ioctl(struct file fp, unsigned int cmd,\n \t\t\tbreak;\n \t\t}\n \t\tset = !!arg;\n-\t\tret = rpmsg_set_flow_control(eptdev-\u003eept, set, eptdev-\u003echinfo.dst);\n+\t\tret = mutex_lock_interruptible(\u0026eptdev-\u003eept_lock);\n+\t\tif (ret)\n+\t\t\tbreak;\n+\t\tif (eptdev-\u003eept)\n+\t\t\tret = rpmsg_set_flow_control(eptdev-\u003eept, set,\n+\t\t\t\t\t\t eptdev-\u003echinfo.dst);\n+\t\telse\n+\t\t\tret = -EPIPE;\n+\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n \t\tbreak;\n \tcase RPMSG_DESTROY_EPT_IOCTL:\n \t\t/ Don't allow to destroy a default endpoint. */\n" }
2/1	2026/10/26 11:45	agent	patch-evaluator	6m Model: core Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "The patch modifies rpmsg_eptdev_ioctl() in drivers/rpmsg/rpmsg_char.c to hold eptdev-\u003eept_lock and check for NULL eptdev-\u003eept during RPMSG_SET_INCOMING_FLOWCONTROL ioctls. However, RPMsg (Remote Processor Messaging) devices are exclusively provided by remote coprocessor subsystems on embedded SoCs (such as Qualcomm GLINK/SMD, MediaTek SCP, or remoteproc virtio devices). On the target architecture (amd64), no RPMsg hardware or virtual devices exist or are emulated in standard QEMU/GCE environments. Because no underlying rpmsg_device can be registered, neither /dev/rpmsg_ctrl* nor /dev/rpmsg* character devices can be instantiated or opened, rendering rpmsg_eptdev_ioctl structurally unreachable.", "WorthFuzzing": false } Instruction: You are an expert Linux kernel maintainer and security engineer. Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on internal assumptions. You must actively use your code access tools to inspect the actual source code, callers, and surrounding context. ================================================================================ 1. CORE TRIAGE PHILOSOPHY ================================================================================ The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs, and newly triggered assertions introduced by the patch series. - REACHABILITY IS THE PRIMARY GATE: Fuzzing can only discover bugs in code that can actually execute in standard virtualized environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap). If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed, regardless of whether it adds assertions or complex logic. - DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS: Patch authors routinely label changes as "cleanups", "refactorings", or state "No functional change intended". Do NOT take these claims at face value. Code refactorings that rearrange logic, introduce helper functions, or alter state management in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs. If reachable executable code is modified or refactored, it MUST be fuzzed. - NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED: When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON, VM_WARN_ON, BUG_ON, lockdep_assert) in reachable code paths, it enforces new or stricter invariants. Even if the author believes the invariant always holds, fuzzing is essential to verify whether an unusual sequence of operations can violate it. ================================================================================ 2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA) ================================================================================ Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories: - Non-kernel and non-executable changes: * Modifications to Documentation/, comments, or spelling fixes. * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/) that do not affect the compiled kernel image (vmlinux) or kernel modules. * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures. * Build system or Kconfig changes that do not alter compiled C logic. - Structurally unreachable hardware: * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU. - Unreachable execution paths: * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during physical PCI hot-unplug or manual sysfs driver unbinding. * Code paths exclusive to architectures other than the target architecture. ================================================================================ 3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA) ================================================================================ Return WorthFuzzing=true whenever the patch touches reachable executable code, including: - Core Subsystems: * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/), BPF, scheduler, core networking, VFS, or syscall handling. - Refactorings and Code Cleanups: * Any restructuring of reachable data structures, helper abstractions, or algorithm flows. - Runtime Assertions and Defensive Checks: * Any introduction or alteration of assertions (WARN_ON, VM_WARN_ON, BUG_ON, etc.) in reachable paths. - Reachable Drivers and Protocols: Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.). ================================================================================ 4. EXTRACTING FocusSymbols (PREVENTING DILUTION) ================================================================================ When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer: - AVOID UBIQUITOUS LIFECYCLE HOT-PATHS: Do NOT list generic, ubiquitous functions called by almost every program in the corpus (including, but not limited to: general memory allocators and deallocators, page fault and trap handlers, or core synchronization primitives; this is not an exhaustive list). Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused", which severely dilutes fuzzing effort away from the actual changes. - TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS: List functions that specifically implement the logic being added or altered, or direct API entrypoints for the subsystem feature under review. - HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h): Compiler-inlined static functions (such as static inlines in mm/.h or include/linux/.h) lack distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters. If the changes are primarily in static inline helpers, identify non-static, feature-specific caller functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers). ================================================================================ 5. IDENTIFYING EnableConfigs ================================================================================ Identify any specific CONFIG_ options required to properly compile and reach the modified code: - Inspect Kconfig files and #ifdef guards; do not make assumptions. - Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed. - Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4"). Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit ef9f789b3f5fe7743026f0349064fb807a2de3c9 Author: syz-cluster <triage@syzkaller.com> Date: Mon Oct 26 11:45:00 2026 +0000 syz-cluster: applied patch under review diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c index 550fda217da45..49c0784fec2e8 100644 --- a/drivers/rpmsg/rpmsg_char.c +++ b/drivers/rpmsg/rpmsg_char.c @@ -343,7 +343,15 @@ static long rpmsg_eptdev_ioctl(struct file fp, unsigned int cmd, break; } set = !!arg; - ret = rpmsg_set_flow_control(eptdev->ept, set, eptdev->chinfo.dst); + ret = mutex_lock_interruptible(&eptdev->ept_lock); + if (ret) + break; + if (eptdev->ept) + ret = rpmsg_set_flow_control(eptdev->ept, set, + eptdev->chinfo.dst); + else + ret = -EPIPE; + mutex_unlock(&eptdev->ept_lock); break; case RPMSG_DESTROY_EPT_IOCTL: / Don't allow to destroy a default endpoint. */
3/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 3110 output: 30 thoughts: 354 Thoughts: Evaluating the Patch for Syzkaller Fuzzing Okay, so the task at hand is to determine if this patch in `drivers/rpmsg/rpmsg_char.c` is worth fuzzing with syzkaller on `amd64`. My initial assessment involves a careful look at the code diff. The patch seems to introduce a mutex around the `rpmsg_set_flow_control` call within `rpmsg_eptdev_ioctl`. It also adds a check for `eptdev->ept` before calling that function, returning `-EPIPE` if it's NULL, and importantly, it also unlocks the mutex. Now, before I jump to any conclusions, I need to understand the context. What is `rpmsg_char`? How is it used? Is it even relevant in a typical syzkaller setup using QEMU? To answer these questions, I'll need to dig into the surrounding code in `drivers/rpmsg/rpmsg_char.c` and its associated Kconfig entries. I'll probably fire up grepper or start reading the file directly to figure this out. I need to understand the control flow, the data structures, and the possible interactions to judge whether the patched code is reachable and whether the changes introduce any new, interesting code paths or potential vulnerabilities that syzkaller could expose. My goal is to determine if this change increases the attack surface or exposes new memory locations or code paths.
4/2	2026/10/26 11:45	tool	grepper	0m Args: { "Expression": "RPMSG_CHAR", "PathPrefixes": [ "drivers/rpmsg/" ] } Results: { "Output": "drivers/rpmsg/Kconfig=6=config RPMSG\n--\ndrivers/rpmsg/Kconfig-8-\ndrivers/rpmsg/Kconfig:9:config RPMSG_CHAR\ndrivers/rpmsg/Kconfig-10-\ttristate \"RPMSG device interface\"\n--\ndrivers/rpmsg/Kconfig=18=config RPMSG_CTRL\ndrivers/rpmsg/Kconfig-19-\ttristate \"RPMSG control interface\"\ndrivers/rpmsg/Kconfig:20:\tdepends on RPMSG \u0026\u0026 ( RPMSG_CHAR \|\| RPMSG_CHAR=n )\ndrivers/rpmsg/Kconfig-21-\thelp\n--\ndrivers/rpmsg/Makefile=2=obj-$(CONFIG_RPMSG)\t\t+= rpmsg_core.o\ndrivers/rpmsg/Makefile:3:obj-$(CONFIG_RPMSG_CHAR)\t+= rpmsg_char.o\ndrivers/rpmsg/Makefile-4-obj-$(CONFIG_RPMSG_CTRL)\t+= rpmsg_ctrl.o\n--\ndrivers/rpmsg/rpmsg_char.h-8-\ndrivers/rpmsg/rpmsg_char.h:9:#if IS_ENABLED(CONFIG_RPMSG_CHAR)\ndrivers/rpmsg/rpmsg_char.h-10-/*\n--\ndrivers/rpmsg/rpmsg_char.h=29=int rpmsg_chrdev_eptdev_destroy(struct device dev, void data);\ndrivers/rpmsg/rpmsg_char.h-30-\ndrivers/rpmsg/rpmsg_char.h:31:#else /IS_ENABLED(CONFIG_RPMSG_CHAR) /\ndrivers/rpmsg/rpmsg_char.h-32-\n--\ndrivers/rpmsg/rpmsg_char.h=39=static inline int rpmsg_chrdev_eptdev_destroy(struct device dev, void data)\n--\ndrivers/rpmsg/rpmsg_char.h-43-\ndrivers/rpmsg/rpmsg_char.h:44:#endif /IS_ENABLED(CONFIG_RPMSG_CHAR) */\ndrivers/rpmsg/rpmsg_char.h-45-\n" }
5/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 4311 output: 33 thoughts: 27 Thoughts: Okay, let's dive into this. Here's my thought process on the matter: Delving into RPMSG Configuration and Implementation Right, time to get my hands dirty. I need to understand the configuration and implementation of the Remote Processor Messaging (RPMSG) framework, specifically as it's handled within the Linux kernel's drivers section. My immediate focus is on two key files: `drivers/rpmsg/Kconfig` and `drivers/rpmsg/rpmsg_char.c`. I'll start with `Kconfig`. That's where all the relevant build options are defined. I expect to find the settings that control whether RPMSG support is compiled into the kernel, what features are enabled, and any dependencies on other kernel subsystems. I'll be looking for things like: the base RPMSG support, specific transport layer options (VirtIO, OpenAMP, etc.), and any character device (char) specific settings. Basically, I want to get a high-level view of how the RPMSG driver is configured and what options are available to a developer. Then, I'll move on to `rpmsg_char.c`. This is where the core logic of the character device driver resides. I'm assuming that it implements the standard character device interface (`open`, `read`, `write`, `ioctl`, etc.) to interact with the RPMSG framework. I'll need to understand how it handles message transmission and reception. I'll be on the lookout for how it translates user-space I/O operations into RPMSG calls, and how it deals with device registration, endpoint management, and any necessary locking. I'll expect to see how it handles message buffers, interrupt handling (if applicable), and error conditions. I will be very interested to understand how this character device sits within the overall RPMSG framework. I'll be particularly interested in comparing and contrasting this to the more standard virtio or shared memory implementations.
6/2	2026/10/26 11:45	tool	read-file	0m Args: { "File": "drivers/rpmsg/Kconfig", "FirstLine": 1, "LineCount": 50 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0\n 2:\t\n 3:\tmenu \"Rpmsg drivers\"\n 4:\t\n 5:\t# RPMSG always gets selected by whoever wants it\n 6:\tconfig RPMSG\n 7:\t\ttristate\n 8:\t\n 9:\tconfig RPMSG_CHAR\n 10:\t\ttristate \"RPMSG device interface\"\n 11:\t\tdepends on RPMSG\n 12:\t\tdepends on NET\n 13:\t\thelp\n 14:\t\t Say Y here to export rpmsg endpoints as device files, usually found\n 15:\t\t in /dev. They make it possible for user-space programs to send and\n 16:\t\t receive rpmsg packets.\n 17:\t\n 18:\tconfig RPMSG_CTRL\n 19:\t\ttristate \"RPMSG control interface\"\n 20:\t\tdepends on RPMSG \u0026\u0026 ( RPMSG_CHAR \|\| RPMSG_CHAR=n )\n 21:\t\thelp\n 22:\t\t Say Y here to enable the support of the /dev/rpmsg_ctrlX API. This API\n 23:\t\t allows user-space programs to create endpoints with specific service name,\n 24:\t\t source and destination addresses.\n 25:\t\n 26:\tconfig RPMSG_NS\n 27:\t\ttristate \"RPMSG name service announcement\"\n 28:\t\tdepends on RPMSG\n 29:\t\thelp\n 30:\t\t Say Y here to enable the support of the name service announcement\n 31:\t\t channel that probes the associated RPMsg device on remote endpoint\n 32:\t\t service announcement.\n 33:\t\n 34:\tconfig RPMSG_MTK_SCP\n 35:\t\ttristate \"MediaTek SCP\"\n 36:\t\tdepends on MTK_SCP\n 37:\t\tselect RPMSG\n 38:\t\thelp\n 39:\t\t Say y here to enable support providing communication channels to\n 40:\t\t remote processors in MediaTek platforms.\n 41:\t\t This use IPI and IPC to communicate with remote processors.\n 42:\t\n 43:\tconfig RPMSG_QCOM_GLINK\n 44:\t\ttristate\n 45:\t\tselect RPMSG\n 46:\t\n 47:\tconfig RPMSG_QCOM_GLINK_RPM\n 48:\t\ttristate \"Qualcomm RPM Glink driver\"\n 49:\t\tselect RPMSG_QCOM_GLINK\n 50:\t\tdepends on HAS_IOMEM\n" }
7/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 5410 output: 17 thoughts: 39 Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue: Investigating RPMSG Driver Selection and Device Provisioning Alright, let's dive into the current state of RPMSG in the kernel. My immediate focus is on which drivers are actually choosing to utilize RPMSG, or, even more critically, which ones are explicitly declaring RPMSG devices. This is a crucial first step in understanding the landscape. I need to know the actors. I'm also curious about the potential role of Virtio here. Can Virtio, in its various flavors, act as a provider for these RPMSG devices? That's a key question. Knowing if Virtio can provision the devices will inform so much more about the landscape of rpmsg and the architecture of the system. Okay, time to do some digging. Time to run a comprehensive `grep` for "RPMSG" across the `Kconfig` files throughout the entire kernel source. That should give me a good birds-eye view of how RPMSG is being integrated, enabled, and configured across the different subsystems. A good search will illuminate which features depend on RPMSG and where the architecture is situated.
8/2	2026/10/26 11:45	tool	grepper	0m Args: { "Expression": "select RPMSG" } Results: { "Output": "drivers/cdx/controller/Kconfig=10=config CDX_CONTROLLER\n--\ndrivers/cdx/controller/Kconfig-13-\tselect REMOTEPROC\ndrivers/cdx/controller/Kconfig:14:\tselect RPMSG\ndrivers/cdx/controller/Kconfig-15-\thelp\n--\ndrivers/media/platform/st/sti/delta/Kconfig=29=config VIDEO_STI_DELTA_DRIVER\n--\ndrivers/media/platform/st/sti/delta/Kconfig-35-\tselect V4L2_MEM2MEM_DEV\ndrivers/media/platform/st/sti/delta/Kconfig:36:\tselect RPMSG\n--\ndrivers/net/wireless/ath/ath11k/Kconfig=13=config ATH11K_AHB\n--\ndrivers/net/wireless/ath/ath11k/Kconfig-16-\tdepends on REMOTEPROC\ndrivers/net/wireless/ath/ath11k/Kconfig:17:\tselect RPMSG\ndrivers/net/wireless/ath/ath11k/Kconfig-18-\tselect QRTR\n--\ndrivers/remoteproc/Kconfig=68=config MTK_SCP\n--\ndrivers/remoteproc/Kconfig-70-\tdepends on ARCH_MEDIATEK \|\| COMPILE_TEST\ndrivers/remoteproc/Kconfig:71:\tselect RPMSG_MTK_SCP\ndrivers/remoteproc/Kconfig-72-\thelp\n--\ndrivers/remoteproc/Kconfig=380=config XLNX_R5_REMOTEPROC\n--\ndrivers/remoteproc/Kconfig-383-\tselect ZYNQMP_FIRMWARE\ndrivers/remoteproc/Kconfig:384:\tselect RPMSG_VIRTIO\ndrivers/remoteproc/Kconfig-385-\tselect MAILBOX\n--\ndrivers/rpmsg/Kconfig=34=config RPMSG_MTK_SCP\n--\ndrivers/rpmsg/Kconfig-36-\tdepends on MTK_SCP\ndrivers/rpmsg/Kconfig:37:\tselect RPMSG\ndrivers/rpmsg/Kconfig-38-\thelp\n--\ndrivers/rpmsg/Kconfig=43=config RPMSG_QCOM_GLINK\ndrivers/rpmsg/Kconfig-44-\ttristate\ndrivers/rpmsg/Kconfig:45:\tselect RPMSG\ndrivers/rpmsg/Kconfig-46-\ndrivers/rpmsg/Kconfig=47=config RPMSG_QCOM_GLINK_RPM\ndrivers/rpmsg/Kconfig-48-\ttristate \"Qualcomm RPM Glink driver\"\ndrivers/rpmsg/Kconfig:49:\tselect RPMSG_QCOM_GLINK\ndrivers/rpmsg/Kconfig-50-\tdepends on HAS_IOMEM\n--\ndrivers/rpmsg/Kconfig=57=config RPMSG_QCOM_GLINK_SMEM\ndrivers/rpmsg/Kconfig-58-\ttristate \"Qualcomm SMEM Glink driver\"\ndrivers/rpmsg/Kconfig:59:\tselect RPMSG_QCOM_GLINK\ndrivers/rpmsg/Kconfig-60-\tdepends on MAILBOX\n--\ndrivers/rpmsg/Kconfig=67=config RPMSG_QCOM_SMD\n--\ndrivers/rpmsg/Kconfig-70-\tdepends on QCOM_SMEM\ndrivers/rpmsg/Kconfig:71:\tselect RPMSG\ndrivers/rpmsg/Kconfig-72-\thelp\n--\ndrivers/rpmsg/Kconfig=77=config RPMSG_VIRTIO\n--\ndrivers/rpmsg/Kconfig-79-\tdepends on HAS_DMA\ndrivers/rpmsg/Kconfig:80:\tselect RPMSG\ndrivers/rpmsg/Kconfig:81:\tselect RPMSG_NS\ndrivers/rpmsg/Kconfig-82-\tselect VIRTIO\n" }
9/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 6663 output: 34 thoughts: 34 Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue: Investigating RPMSG_VIRTIO Alright, that piqued my interest. Let's dig into this `RPMSG_VIRTIO` construct. My first stop, as always, is the `drivers/rpmsg/Kconfig` file. I need to understand its configuration options, dependencies, and intended purpose within the greater RPMSG framework. Knowing its Kconfig defines its build-time characteristics. It’ll give me the essential context I need before I begin to think about its role in the bigger picture, and any potential issues or avenues for optimization. Understanding its context means I can see what I can achieve with it. I need to assess how it integrates with other components and if it aligns with my current project’s goals or potential research interests. Time to start the deep dive.
10/2	2026/10/26 11:45	tool	read-file	0m Args: { "File": "drivers/rpmsg/Kconfig", "FirstLine": 75, "LineCount": 40 } Results: { "Contents": " 75:\t\t platforms.\n 76:\t\n 77:\tconfig RPMSG_VIRTIO\n 78:\t\ttristate \"Virtio RPMSG bus driver\"\n 79:\t\tdepends on HAS_DMA\n 80:\t\tselect RPMSG\n 81:\t\tselect RPMSG_NS\n 82:\t\tselect VIRTIO\n 83:\t\n 84:\tendmenu\n" }
11/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 7031 output: 39 thoughts: 50 Thoughts: Okay, let's dive into this. RPMSG Char Driver Deep Dive Alright, time to get my hands dirty. I want to understand the inner workings of the RPMSG character driver. The file of interest is `drivers/rpmsg/rpmsg_char.c`. I'll start by focusing on the area around line 343, and then I'll expand my focus to read through the rest of the file. This usually gives me a good overview of the driver's core functionality and how it handles message passing via RPMSG channels. I'll be looking for how it interacts with the underlying RPMSG transport layer, how it manages character devices, and how it handles data transfer. Let's see what interesting techniques the developers have used.
12/2	2026/10/26 11:45	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_char.c", "FirstLine": 310, "LineCount": 80 } Results: { "Contents": " 310:\t\t\treturn EPOLLERR;\n 311:\t\n 312:\t\tpoll_wait(filp, \u0026eptdev-\u003ereadq, wait);\n 313:\t\n 314:\t\tif (!skb_queue_empty(\u0026eptdev-\u003equeue))\n 315:\t\t\tmask \|= EPOLLIN \| EPOLLRDNORM;\n 316:\t\n 317:\t\tif (eptdev-\u003eremote_flow_updated)\n 318:\t\t\tmask \|= EPOLLPRI;\n 319:\t\n 320:\t\tmutex_lock(\u0026eptdev-\u003eept_lock);\n 321:\t\tmask \|= rpmsg_poll(eptdev-\u003eept, filp, wait);\n 322:\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n 323:\t\n 324:\t\treturn mask;\n 325:\t}\n 326:\t\n 327:\tstatic long rpmsg_eptdev_ioctl(struct file fp, unsigned int cmd,\n 328:\t\t\t\t unsigned long arg)\n 329:\t{\n 330:\t\tstruct rpmsg_eptdev eptdev = fp-\u003eprivate_data;\n 331:\t\n 332:\t\tbool set;\n 333:\t\tint ret;\n 334:\t\n 335:\t\tswitch (cmd) {\n 336:\t\tcase RPMSG_GET_OUTGOING_FLOWCONTROL:\n 337:\t\t\teptdev-\u003eremote_flow_updated = false;\n 338:\t\t\tret = put_user(eptdev-\u003eremote_flow_restricted, (int __user )arg);\n 339:\t\t\tbreak;\n 340:\t\tcase RPMSG_SET_INCOMING_FLOWCONTROL:\n 341:\t\t\tif (arg \u003e 1) {\n 342:\t\t\t\tret = -EINVAL;\n 343:\t\t\t\tbreak;\n 344:\t\t\t}\n 345:\t\t\tset = !!arg;\n 346:\t\t\tret = mutex_lock_interruptible(\u0026eptdev-\u003eept_lock);\n 347:\t\t\tif (ret)\n 348:\t\t\t\tbreak;\n 349:\t\t\tif (eptdev-\u003eept)\n 350:\t\t\t\tret = rpmsg_set_flow_control(eptdev-\u003eept, set,\n 351:\t\t\t\t\t\t\t eptdev-\u003echinfo.dst);\n 352:\t\t\telse\n 353:\t\t\t\tret = -EPIPE;\n 354:\t\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n 355:\t\t\tbreak;\n 356:\t\tcase RPMSG_DESTROY_EPT_IOCTL:\n 357:\t\t\t/ Don't allow to destroy a default endpoint. /\n 358:\t\t\tif (eptdev-\u003edefault_ept) {\n 359:\t\t\t\tret = -EINVAL;\n 360:\t\t\t\tbreak;\n 361:\t\t\t}\n 362:\t\t\tret = rpmsg_chrdev_eptdev_destroy(\u0026eptdev-\u003edev, NULL);\n 363:\t\t\tbreak;\n 364:\t\tdefault:\n 365:\t\t\tret = -EINVAL;\n 366:\t\t}\n 367:\t\n 368:\t\treturn ret;\n 369:\t}\n 370:\t\n 371:\tstatic const struct file_operations rpmsg_eptdev_fops = {\n 372:\t\t.owner = THIS_MODULE,\n 373:\t\t.open = rpmsg_eptdev_open,\n 374:\t\t.release = rpmsg_eptdev_release,\n 375:\t\t.read_iter = rpmsg_eptdev_read_iter,\n 376:\t\t.write_iter = rpmsg_eptdev_write_iter,\n 377:\t\t.poll = rpmsg_eptdev_poll,\n 378:\t\t.unlocked_ioctl = rpmsg_eptdev_ioctl,\n 379:\t\t.compat_ioctl = compat_ptr_ioctl,\n 380:\t};\n 381:\t\n 382:\tstatic ssize_t name_show(struct device dev, struct device_attribute attr,\n 383:\t\t\t\t char buf)\n 384:\t{\n 385:\t\tstruct rpmsg_eptdev *eptdev = dev_get_drvdata(dev);\n 386:\t\n 387:\t\treturn sysfs_emit(buf, \"%s\\n\", eptdev-\u003echinfo.name);\n 388:\t}\n 389:\tstatic DEVICE_ATTR_RO(name);\n" }
13/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 8435 output: 38 thoughts: 33 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into rpmsg_char.c for Endpoint Device Creation Okay, time to get a bit deeper into the guts of the rpmsg framework. I'm specifically interested in how these `rpmsg_eptdev` devices, those character devices representing our endpoints, are actually registered and brought to life. I need to understand the lifecycle here. I know the basic concept, but the devil is always in the details, and I want a clearer picture of the registration and creation process outlined in `drivers/rpmsg/rpmsg_char.c`. Let's see how the kernel handles the low-level character device creation and how it links back into the broader rpmsg infrastructure. I'm anticipating there's some interesting work related to device probing and driver binding, probably utilizing some of the core rpmsg functions.
14/2	2026/10/26 11:45	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_char.c", "FirstLine": 1, "LineCount": 100 } Results: { "Contents": " 1:\t// SPDX-License-Identifier: GPL-2.0\n 2:\t/\n 3:\t Copyright (C) 2022, STMicroelectronics\n 4:\t * Copyright (c) 2016, Linaro Ltd.\n 5:\t * Copyright (c) 2012, Michal Simek \u003cmonstr@monstr.eu\u003e\n 6:\t * Copyright (c) 2012, PetaLogix\n 7:\t * Copyright (c) 2011, Texas Instruments, Inc.\n 8:\t * Copyright (c) 2011, Google, Inc.\n 9:\t \n 10:\t Based on rpmsg performance statistics driver by Michal Simek, which in turn\n 11:\t * was based on TI \u0026 Google OMX rpmsg driver.\n 12:\t /\n 13:\t\n 14:\t#define pr_fmt(fmt)\tKBUILD_MODNAME \": \" fmt\n 15:\t\n 16:\t#include \u003clinux/cdev.h\u003e\n 17:\t#include \u003clinux/device.h\u003e\n 18:\t#include \u003clinux/fs.h\u003e\n 19:\t#include \u003clinux/idr.h\u003e\n 20:\t#include \u003clinux/kernel.h\u003e\n 21:\t#include \u003clinux/module.h\u003e\n 22:\t#include \u003clinux/poll.h\u003e\n 23:\t#include \u003clinux/rpmsg.h\u003e\n 24:\t#include \u003clinux/skbuff.h\u003e\n 25:\t#include \u003clinux/slab.h\u003e\n 26:\t#include \u003clinux/uaccess.h\u003e\n 27:\t#include \u003cuapi/linux/rpmsg.h\u003e\n 28:\t\n 29:\t#include \"rpmsg_char.h\"\n 30:\t#include \"rpmsg_internal.h\"\n 31:\t\n 32:\t#define RPMSG_DEV_MAX\t(MINORMASK + 1)\n 33:\t\n 34:\tstatic dev_t rpmsg_major;\n 35:\t\n 36:\tstatic DEFINE_IDA(rpmsg_ept_ida);\n 37:\tstatic DEFINE_IDA(rpmsg_minor_ida);\n 38:\t\n 39:\t#define dev_to_eptdev(dev) container_of(dev, struct rpmsg_eptdev, dev)\n 40:\t#define cdev_to_eptdev(i_cdev) container_of(i_cdev, struct rpmsg_eptdev, cdev)\n 41:\t\n 42:\t/\n 43:\t struct rpmsg_eptdev - endpoint device context\n 44:\t * @dev:\tendpoint device\n 45:\t * @cdev:\tcdev for the endpoint device\n 46:\t * @rpdev:\tunderlaying rpmsg device\n 47:\t * @chinfo:\tinfo used to open the endpoint\n 48:\t * @ept_lock:\tsynchronization of @ept modifications\n 49:\t * @ept:\trpmsg endpoint reference, when open\n 50:\t * @queue_lock:\tsynchronization of @queue operations\n 51:\t * @queue:\tincoming message queue\n 52:\t * @readq:\twait object for incoming queue\n 53:\t * @default_ept: set to channel default endpoint if the default endpoint should be re-used\n 54:\t * on device open to prevent endpoint address update.\n 55:\t * @remote_flow_restricted: to indicate if the remote has requested for flow to be limited\n 56:\t * @remote_flow_updated: to indicate if the flow control has been requested\n 57:\t /\n 58:\tstruct rpmsg_eptdev {\n 59:\t\tstruct device dev;\n 60:\t\tstruct cdev cdev;\n 61:\t\n 62:\t\tstruct rpmsg_device rpdev;\n 63:\t\tstruct rpmsg_channel_info chinfo;\n 64:\t\n 65:\t\tstruct mutex ept_lock;\n 66:\t\tstruct rpmsg_endpoint ept;\n 67:\t\tstruct rpmsg_endpoint default_ept;\n 68:\t\n 69:\t\tspinlock_t queue_lock;\n 70:\t\tstruct sk_buff_head queue;\n 71:\t\twait_queue_head_t readq;\n 72:\t\n 73:\t\tbool remote_flow_restricted;\n 74:\t\tbool remote_flow_updated;\n 75:\t};\n 76:\t\n 77:\tint rpmsg_chrdev_eptdev_destroy(struct device dev, void data)\n 78:\t{\n 79:\t\tstruct rpmsg_eptdev eptdev = dev_to_eptdev(dev);\n 80:\t\n 81:\t\tmutex_lock(\u0026eptdev-\u003eept_lock);\n 82:\t\tif (!eptdev-\u003erpdev) {\n 83:\t\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n 84:\t\t\treturn 0;\n 85:\t\t}\n 86:\t\n 87:\t\teptdev-\u003erpdev = NULL;\n 88:\t\tif (eptdev-\u003eept) {\n 89:\t\t\t/ The default endpoint is released by the rpmsg core /\n 90:\t\t\tif (!eptdev-\u003edefault_ept)\n 91:\t\t\t\trpmsg_destroy_ept(eptdev-\u003eept);\n 92:\t\t\teptdev-\u003eept = NULL;\n 93:\t\t}\n 94:\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n 95:\t\n 96:\t\t/ wake up any blocked readers */\n 97:\t\twake_up_interruptible(\u0026eptdev-\u003ereadq);\n 98:\t\n 99:\t\tcdev_device_del(\u0026eptdev-\u003ecdev, \u0026eptdev-\u003edev);\n 100:\t\tput_device(\u0026eptdev-\u003edev);\n" }
15/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 10180 output: 40 thoughts: 56 Thoughts: Here's my understanding of how I'd approach this, as if it were my thought process: Diving into rpmsg Endpoint Creation Okay, so I want to get a solid grasp on the nitty-gritty of how the `rpmsg_chrdev_eptdev_create` function functions, and how the control path in `rpmsg_ctrl` sets up the endpoint devices. I'll need to dig into the code and see how things tie together. My first instinct is to zero in on the relevant code. I think a focused look at lines 400 to 550 of `drivers/rpmsg/rpmsg_char.c` is the right place to begin this investigation. That should cover the core logic of the `rpmsg_chrdev_eptdev_create` function and potentially reveal some of the interactions with the control interface. From there, I can start to piece together the sequence of events and the data structures involved. Time to get coding!
16/2	2026/10/26 11:45	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_char.c", "FirstLine": 400, "LineCount": 100 } Results: { "Contents": " 400:\tstatic ssize_t dst_show(struct device dev, struct device_attribute attr,\n 401:\t\t\t\t char buf)\n 402:\t{\n 403:\t\tstruct rpmsg_eptdev eptdev = dev_get_drvdata(dev);\n 404:\t\n 405:\t\treturn sysfs_emit(buf, \"%d\\n\", eptdev-\u003echinfo.dst);\n 406:\t}\n 407:\tstatic DEVICE_ATTR_RO(dst);\n 408:\t\n 409:\tstatic struct attribute rpmsg_eptdev_attrs[] = {\n 410:\t\t\u0026dev_attr_name.attr,\n 411:\t\t\u0026dev_attr_src.attr,\n 412:\t\t\u0026dev_attr_dst.attr,\n 413:\t\tNULL\n 414:\t};\n 415:\tATTRIBUTE_GROUPS(rpmsg_eptdev);\n 416:\t\n 417:\tstatic void rpmsg_eptdev_release_device(struct device dev)\n 418:\t{\n 419:\t\tstruct rpmsg_eptdev eptdev = dev_to_eptdev(dev);\n 420:\t\n 421:\t\tida_free(\u0026rpmsg_ept_ida, dev-\u003eid);\n 422:\t\tida_free(\u0026rpmsg_minor_ida, MINOR(eptdev-\u003edev.devt));\n 423:\t\tkfree(eptdev);\n 424:\t}\n 425:\t\n 426:\tstatic struct rpmsg_eptdev rpmsg_chrdev_eptdev_alloc(struct rpmsg_device rpdev,\n 427:\t\t\t\t\t\t\t struct device parent)\n 428:\t{\n 429:\t\tstruct rpmsg_eptdev eptdev;\n 430:\t\tstruct device dev;\n 431:\t\n 432:\t\teptdev = kzalloc_obj(eptdev);\n 433:\t\tif (!eptdev)\n 434:\t\t\treturn ERR_PTR(-ENOMEM);\n 435:\t\n 436:\t\tdev = \u0026eptdev-\u003edev;\n 437:\t\teptdev-\u003erpdev = rpdev;\n 438:\t\n 439:\t\tmutex_init(\u0026eptdev-\u003eept_lock);\n 440:\t\tspin_lock_init(\u0026eptdev-\u003equeue_lock);\n 441:\t\tskb_queue_head_init(\u0026eptdev-\u003equeue);\n 442:\t\tinit_waitqueue_head(\u0026eptdev-\u003ereadq);\n 443:\t\n 444:\t\tdevice_initialize(dev);\n 445:\t\tdev-\u003eclass = \u0026rpmsg_class;\n 446:\t\tdev-\u003eparent = parent;\n 447:\t\tdev-\u003egroups = rpmsg_eptdev_groups;\n 448:\t\tdev_set_drvdata(dev, eptdev);\n 449:\t\n 450:\t\tcdev_init(\u0026eptdev-\u003ecdev, \u0026rpmsg_eptdev_fops);\n 451:\t\teptdev-\u003ecdev.owner = THIS_MODULE;\n 452:\t\n 453:\t\treturn eptdev;\n 454:\t}\n 455:\t\n 456:\tstatic int rpmsg_chrdev_eptdev_add(struct rpmsg_eptdev eptdev, struct rpmsg_channel_info chinfo)\n 457:\t{\n 458:\t\tstruct device dev = \u0026eptdev-\u003edev;\n 459:\t\tint ret;\n 460:\t\n 461:\t\teptdev-\u003echinfo = chinfo;\n 462:\t\n 463:\t\tret = ida_alloc_max(\u0026rpmsg_minor_ida, RPMSG_DEV_MAX - 1, GFP_KERNEL);\n 464:\t\tif (ret \u003c 0)\n 465:\t\t\tgoto free_eptdev;\n 466:\t\tdev-\u003edevt = MKDEV(MAJOR(rpmsg_major), ret);\n 467:\t\n 468:\t\tret = ida_alloc(\u0026rpmsg_ept_ida, GFP_KERNEL);\n 469:\t\tif (ret \u003c 0)\n 470:\t\t\tgoto free_minor_ida;\n 471:\t\tdev-\u003eid = ret;\n 472:\t\tdev_set_name(dev, \"rpmsg%d\", ret);\n 473:\t\n 474:\t\tret = cdev_device_add(\u0026eptdev-\u003ecdev, \u0026eptdev-\u003edev);\n 475:\t\tif (ret)\n 476:\t\t\tgoto free_ept_ida;\n 477:\t\n 478:\t\t/ We can now rely on the release function for cleanup /\n 479:\t\tdev-\u003erelease = rpmsg_eptdev_release_device;\n 480:\t\n 481:\t\treturn ret;\n 482:\t\n 483:\tfree_ept_ida:\n 484:\t\tida_free(\u0026rpmsg_ept_ida, dev-\u003eid);\n 485:\tfree_minor_ida:\n 486:\t\tida_free(\u0026rpmsg_minor_ida, MINOR(dev-\u003edevt));\n 487:\tfree_eptdev:\n 488:\t\tput_device(dev);\n 489:\t\tkfree(eptdev);\n 490:\t\n 491:\t\treturn ret;\n 492:\t}\n 493:\t\n 494:\tint rpmsg_chrdev_eptdev_create(struct rpmsg_device rpdev, struct device parent,\n 495:\t\t\t\t struct rpmsg_channel_info chinfo)\n 496:\t{\n 497:\t\tstruct rpmsg_eptdev eptdev;\n 498:\t\n 499:\t\teptdev = rpmsg_chrdev_eptdev_alloc(rpdev, parent);\n" }
17/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 12004 output: 24 thoughts: 20 Thoughts: Okay, here's my summary, tailored for an expert audience, as if I'm thinking these thoughts: Analyzing the Call Sites of `rpmsg_chrdev_eptdev_create` Right, let's dive in. I need to understand the lifecycle of this character device endpoint creation function, `rpmsg_chrdev_eptdev_create`. Where are the entry points? My focus is, naturally, on tracing the control flow that leads into this function. I need to identify the crucial calling contexts – the drivers, the initialization sequences, the resource allocation steps that trigger the endpoint's instantiation. Knowing the call graph is the foundation for comprehending its role in the larger Remote Processor Messaging (RPMsg) framework. I'm thinking, "Let's track down those call sites." I'll need to use my usual tools – grep, cscope, maybe some static analysis if it warrants the complexity – to find all instances. This initial analysis is critical to building a mental map of how the system works and I expect it to open the door to further investigation.
18/2	2026/10/26 11:45	tool	grepper	0m Args: { "Expression": "rpmsg_chrdev_eptdev_create" } Results: { "Output": "drivers/rpmsg/rpmsg_char.c=456=static int rpmsg_chrdev_eptdev_add(struct rpmsg_eptdev eptdev, struct rpmsg_channel_info chinfo)\n--\ndrivers/rpmsg/rpmsg_char.c-493-\ndrivers/rpmsg/rpmsg_char.c:494:int rpmsg_chrdev_eptdev_create(struct rpmsg_device rpdev, struct device parent,\ndrivers/rpmsg/rpmsg_char.c-495-\t\t\t struct rpmsg_channel_info chinfo)\n--\ndrivers/rpmsg/rpmsg_char.c-504-}\ndrivers/rpmsg/rpmsg_char.c:505:EXPORT_SYMBOL(rpmsg_chrdev_eptdev_create);\ndrivers/rpmsg/rpmsg_char.c-506-\n--\ndrivers/rpmsg/rpmsg_char.h-10-/\ndrivers/rpmsg/rpmsg_char.h:11: rpmsg_chrdev_eptdev_create() - register char device based on an endpoint\ndrivers/rpmsg/rpmsg_char.h-12- * @rpdev: prepared rpdev to be used for creating endpoints\n--\ndrivers/rpmsg/rpmsg_char.h-18- /\ndrivers/rpmsg/rpmsg_char.h:19:int rpmsg_chrdev_eptdev_create(struct rpmsg_device rpdev, struct device parent,\ndrivers/rpmsg/rpmsg_char.h-20-\t\t\t struct rpmsg_channel_info chinfo);\n--\ndrivers/rpmsg/rpmsg_char.h=29=int rpmsg_chrdev_eptdev_destroy(struct device dev, void data);\n--\ndrivers/rpmsg/rpmsg_char.h-32-\ndrivers/rpmsg/rpmsg_char.h:33:static inline int rpmsg_chrdev_eptdev_create(struct rpmsg_device rpdev, struct device parent,\ndrivers/rpmsg/rpmsg_char.h-34-\t\t\t\t\t struct rpmsg_channel_info chinfo)\n--\ndrivers/rpmsg/rpmsg_ctrl.c=74=static long rpmsg_ctrldev_ioctl(struct file fp, unsigned int cmd,\n--\ndrivers/rpmsg/rpmsg_ctrl.c-94-\tcase RPMSG_CREATE_EPT_IOCTL:\ndrivers/rpmsg/rpmsg_ctrl.c:95:\t\tret = rpmsg_chrdev_eptdev_create(ctrldev-\u003erpdev, \u0026ctrldev-\u003edev, chinfo);\ndrivers/rpmsg/rpmsg_ctrl.c-96-\t\tbreak;\n" }
19/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 12935 output: 39 thoughts: 119 Thoughts: Here's my analysis of the provided code snippet, broken down as I'd approach it: Diving into RPMSG Endpoint Creation Okay, so I'm looking at `drivers/rpmsg/rpmsg_ctrl.c`, specifically the `rpmsg_ctrldev_ioctl` function. It's handling an `RPMSG_CREATE_EPT_IOCTL` call, and the key operation here is `rpmsg_chrdev_eptdev_create`. My immediate thought is, this is where a character device endpoint is being created within the RPMSG framework. Now, I need to understand the full picture. My next logical step is to see how this interacts with the character device driver in general, I suspect it's registered elsewhere. The line `rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);` makes me believe it's going to use this character device. Therefore, I'm going to need to dig deeper in the character device. To fully understand what is going on, I'm going to scan through `drivers/rpmsg/rpmsg_char.c`, probably looking at the core registration process and how it handles endpoints. Specifically, I'll need to read lines 500-600, hoping to find the endpoint creation logic and its interaction with the character device itself. This should tell me if the character device driver is also involved in the driver registration.
20/2	2026/10/26 11:45	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_char.c", "FirstLine": 500, "LineCount": 80 } Results: { "Contents": " 500:\t\tif (IS_ERR(eptdev))\n 501:\t\t\treturn PTR_ERR(eptdev);\n 502:\t\n 503:\t\treturn rpmsg_chrdev_eptdev_add(eptdev, chinfo);\n 504:\t}\n 505:\tEXPORT_SYMBOL(rpmsg_chrdev_eptdev_create);\n 506:\t\n 507:\tstatic int rpmsg_chrdev_probe(struct rpmsg_device rpdev)\n 508:\t{\n 509:\t\tstruct rpmsg_channel_info chinfo;\n 510:\t\tstruct rpmsg_eptdev eptdev;\n 511:\t\tstruct device dev = \u0026rpdev-\u003edev;\n 512:\t\tint ret;\n 513:\t\n 514:\t\tmemcpy(chinfo.name, rpdev-\u003eid.name, RPMSG_NAME_SIZE);\n 515:\t\tchinfo.src = rpdev-\u003esrc;\n 516:\t\tchinfo.dst = rpdev-\u003edst;\n 517:\t\n 518:\t\teptdev = rpmsg_chrdev_eptdev_alloc(rpdev, dev);\n 519:\t\tif (IS_ERR(eptdev))\n 520:\t\t\treturn PTR_ERR(eptdev);\n 521:\t\n 522:\t\t/ Set the default_ept to the rpmsg device endpoint /\n 523:\t\teptdev-\u003edefault_ept = rpdev-\u003eept;\n 524:\t\n 525:\t\tret = rpmsg_chrdev_eptdev_add(eptdev, chinfo);\n 526:\t\n 527:\t\tif (ret)\n 528:\t\t\treturn ret;\n 529:\t\t/\n 530:\t\t * The rpmsg_ept_cb uses priv parameter to get its rpmsg_eptdev context.\n 531:\t\t Stored it in default_ept priv field.\n 532:\t\t /\n 533:\t\teptdev-\u003edefault_ept-\u003epriv = eptdev;\n 534:\t\n 535:\t\treturn 0;\n 536:\t}\n 537:\t\n 538:\tstatic void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)\n 539:\t{\n 540:\t\tint ret;\n 541:\t\n 542:\t\tret = device_for_each_child(\u0026rpdev-\u003edev, NULL, rpmsg_chrdev_eptdev_destroy);\n 543:\t\tif (ret)\n 544:\t\t\tdev_warn(\u0026rpdev-\u003edev, \"failed to destroy endpoints: %d\\n\", ret);\n 545:\t}\n 546:\t\n 547:\tstatic struct rpmsg_device_id rpmsg_chrdev_id_table[] = {\n 548:\t\t{ .name\t= \"rpmsg-raw\" },\n 549:\t\t{ .name\t= \"rpmsg_chrdev\" },\n 550:\t\t{ },\n 551:\t};\n 552:\tMODULE_DEVICE_TABLE(rpmsg, rpmsg_chrdev_id_table);\n 553:\t\n 554:\tstatic struct rpmsg_driver rpmsg_chrdev_driver = {\n 555:\t\t.probe = rpmsg_chrdev_probe,\n 556:\t\t.remove = rpmsg_chrdev_remove,\n 557:\t\t.callback = rpmsg_ept_cb,\n 558:\t\t.id_table = rpmsg_chrdev_id_table,\n 559:\t\t.drv.name = \"rpmsg_chrdev\",\n 560:\t};\n 561:\t\n 562:\tstatic int rpmsg_chrdev_init(void)\n 563:\t{\n 564:\t\tint ret;\n 565:\t\n 566:\t\tret = alloc_chrdev_region(\u0026rpmsg_major, 0, RPMSG_DEV_MAX, \"rpmsg_char\");\n 567:\t\tif (ret \u003c 0) {\n 568:\t\t\tpr_err(\"failed to allocate char dev region\\n\");\n 569:\t\t\treturn ret;\n 570:\t\t}\n 571:\t\n 572:\t\tret = register_rpmsg_driver(\u0026rpmsg_chrdev_driver);\n 573:\t\tif (ret \u003c 0) {\n 574:\t\t\tpr_err(\"rpmsg: failed to register rpmsg raw driver\\n\");\n 575:\t\t\tgoto free_region;\n 576:\t\t}\n 577:\t\n 578:\t\treturn 0;\n 579:\t\n" }
21/2	2026/10/26 11:45	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14615 output: 31 thoughts: 106 Thoughts: Investigating RPMSG Reachability in Virtualized Environments Okay, let's get down to brass tacks. I need to figure out if I can even have an rpmsg device, or instantiate one, in a standard virtualized environment like QEMU or Google Compute Engine, specifically on amd64. First, the crucial question: what kind of bus does RPMSG use? Right, let's see, that's what's key here. It seems like the standard is `RPMSG_VIRTIO`. Now the question is - how does this work and where is this device? I need to figure out how `rpmsg_virtio` is probed and initialized. Looks like I should check the kernel source, specifically `drivers/rpmsg/virtio_rpmsg_bus.c`. That should give me the answers I need.
22/2	2026/10/26 11:46	tool	grepper	0m Args: { "Expression": "virtio_rpmsg", "PathPrefixes": [ "drivers/rpmsg/" ] } Results: { "Output": "drivers/rpmsg/Makefile=12=obj-$(CONFIG_RPMSG_QCOM_SMD)\t+= qcom_smd.o\ndrivers/rpmsg/Makefile:13:obj-$(CONFIG_RPMSG_VIRTIO)\t+= virtio_rpmsg_bus.o\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=83=struct rpmsg_hdr {\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-93-/*\ndrivers/rpmsg/virtio_rpmsg_bus.c:94: struct virtio_rpmsg_channel - rpmsg channel descriptor\ndrivers/rpmsg/virtio_rpmsg_bus.c-95- * @rpdev: the rpmsg channel device\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-100- /\ndrivers/rpmsg/virtio_rpmsg_bus.c:101:struct virtio_rpmsg_channel {\ndrivers/rpmsg/virtio_rpmsg_bus.c-102-\tstruct rpmsg_device rpdev;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-106-\ndrivers/rpmsg/virtio_rpmsg_bus.c:107:#define to_virtio_rpmsg_channel(_rpdev) \\\ndrivers/rpmsg/virtio_rpmsg_bus.c:108:\tcontainer_of(_rpdev, struct virtio_rpmsg_channel, rpdev)\ndrivers/rpmsg/virtio_rpmsg_bus.c-109-\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-137-\ndrivers/rpmsg/virtio_rpmsg_bus.c:138:static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint ept);\ndrivers/rpmsg/virtio_rpmsg_bus.c:139:static int virtio_rpmsg_send(struct rpmsg_endpoint ept, const void data, int len);\ndrivers/rpmsg/virtio_rpmsg_bus.c:140:static int virtio_rpmsg_sendto(struct rpmsg_endpoint ept, const void data,\ndrivers/rpmsg/virtio_rpmsg_bus.c-141-\t\t\t int len, u32 dst);\ndrivers/rpmsg/virtio_rpmsg_bus.c:142:static int virtio_rpmsg_trysend(struct rpmsg_endpoint ept, const void data,\ndrivers/rpmsg/virtio_rpmsg_bus.c-143-\t\t\t\tint len);\ndrivers/rpmsg/virtio_rpmsg_bus.c:144:static int virtio_rpmsg_trysendto(struct rpmsg_endpoint ept, const void data,\ndrivers/rpmsg/virtio_rpmsg_bus.c-145-\t\t\t\t int len, u32 dst);\ndrivers/rpmsg/virtio_rpmsg_bus.c:146:static __poll_t virtio_rpmsg_poll(struct rpmsg_endpoint ept, struct file filp,\ndrivers/rpmsg/virtio_rpmsg_bus.c-147-\t\t\t\t poll_table wait);\ndrivers/rpmsg/virtio_rpmsg_bus.c:148:static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint ept);\ndrivers/rpmsg/virtio_rpmsg_bus.c-149-static struct rpmsg_device __rpmsg_create_channel(struct virtproc_info vrp,\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=152=static const struct rpmsg_endpoint_ops virtio_endpoint_ops = {\ndrivers/rpmsg/virtio_rpmsg_bus.c:153:\t.destroy_ept = virtio_rpmsg_destroy_ept,\ndrivers/rpmsg/virtio_rpmsg_bus.c:154:\t.send = virtio_rpmsg_send,\ndrivers/rpmsg/virtio_rpmsg_bus.c:155:\t.sendto = virtio_rpmsg_sendto,\ndrivers/rpmsg/virtio_rpmsg_bus.c:156:\t.trysend = virtio_rpmsg_trysend,\ndrivers/rpmsg/virtio_rpmsg_bus.c:157:\t.trysendto = virtio_rpmsg_trysendto,\ndrivers/rpmsg/virtio_rpmsg_bus.c:158:\t.poll = virtio_rpmsg_poll,\ndrivers/rpmsg/virtio_rpmsg_bus.c:159:\t.get_mtu = virtio_rpmsg_get_mtu,\ndrivers/rpmsg/virtio_rpmsg_bus.c-160-};\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=205=static struct rpmsg_endpoint __rpmsg_create_ept(struct virtproc_info vrp,\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-254-\ndrivers/rpmsg/virtio_rpmsg_bus.c:255:static struct rpmsg_device virtio_rpmsg_create_channel(struct rpmsg_device rpdev,\ndrivers/rpmsg/virtio_rpmsg_bus.c-256-\t\t\t\t\t\t\tstruct rpmsg_channel_info chinfo)\ndrivers/rpmsg/virtio_rpmsg_bus.c-257-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:258:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-259-\tstruct virtproc_info vrp = vch-\u003evrp;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-263-\ndrivers/rpmsg/virtio_rpmsg_bus.c:264:static int virtio_rpmsg_release_channel(struct rpmsg_device rpdev,\ndrivers/rpmsg/virtio_rpmsg_bus.c-265-\t\t\t\t\tstruct rpmsg_channel_info chinfo)\ndrivers/rpmsg/virtio_rpmsg_bus.c-266-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:267:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-268-\tstruct virtproc_info vrp = vch-\u003evrp;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-272-\ndrivers/rpmsg/virtio_rpmsg_bus.c:273:static struct rpmsg_endpoint virtio_rpmsg_create_ept(struct rpmsg_device rpdev,\ndrivers/rpmsg/virtio_rpmsg_bus.c-274-\t\t\t\t\t\t rpmsg_rx_cb_t cb,\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-277-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:278:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-279-\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=294=__rpmsg_destroy_ept(struct virtproc_info vrp, struct rpmsg_endpoint ept)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-308-\ndrivers/rpmsg/virtio_rpmsg_bus.c:309:static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint ept)\ndrivers/rpmsg/virtio_rpmsg_bus.c-310-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:311:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(ept-\u003erpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-312-\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-315-\ndrivers/rpmsg/virtio_rpmsg_bus.c:316:static int virtio_rpmsg_announce_create(struct rpmsg_device rpdev)\ndrivers/rpmsg/virtio_rpmsg_bus.c-317-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:318:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-319-\tstruct virtproc_info vrp = vch-\u003evrp;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-339-\ndrivers/rpmsg/virtio_rpmsg_bus.c:340:static int virtio_rpmsg_announce_destroy(struct rpmsg_device rpdev)\ndrivers/rpmsg/virtio_rpmsg_bus.c-341-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:342:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-343-\tstruct virtproc_info vrp = vch-\u003evrp;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-363-\ndrivers/rpmsg/virtio_rpmsg_bus.c:364:static const struct rpmsg_device_ops virtio_rpmsg_ops = {\ndrivers/rpmsg/virtio_rpmsg_bus.c:365:\t.create_channel = virtio_rpmsg_create_channel,\ndrivers/rpmsg/virtio_rpmsg_bus.c:366:\t.release_channel = virtio_rpmsg_release_channel,\ndrivers/rpmsg/virtio_rpmsg_bus.c:367:\t.create_ept = virtio_rpmsg_create_ept,\ndrivers/rpmsg/virtio_rpmsg_bus.c:368:\t.announce_create = virtio_rpmsg_announce_create,\ndrivers/rpmsg/virtio_rpmsg_bus.c:369:\t.announce_destroy = virtio_rpmsg_announce_destroy,\ndrivers/rpmsg/virtio_rpmsg_bus.c-370-};\ndrivers/rpmsg/virtio_rpmsg_bus.c-371-\ndrivers/rpmsg/virtio_rpmsg_bus.c:372:static void virtio_rpmsg_release_device(struct device dev)\ndrivers/rpmsg/virtio_rpmsg_bus.c-373-{\ndrivers/rpmsg/virtio_rpmsg_bus.c-374-\tstruct rpmsg_device rpdev = to_rpmsg_device(dev);\ndrivers/rpmsg/virtio_rpmsg_bus.c:375:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-376-\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=385=static struct rpmsg_device __rpmsg_create_channel(struct virtproc_info vrp,\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-387-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:388:\tstruct virtio_rpmsg_channel vch;\ndrivers/rpmsg/virtio_rpmsg_bus.c-389-\tstruct rpmsg_device rpdev;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-413-\trpdev-\u003edst = chinfo-\u003edst;\ndrivers/rpmsg/virtio_rpmsg_bus.c:414:\trpdev-\u003eops = \u0026virtio_rpmsg_ops;\ndrivers/rpmsg/virtio_rpmsg_bus.c-415-\trpdev-\u003elittle_endian = virtio_is_little_endian(vrp-\u003evdev);\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-425-\trpdev-\u003edev.parent = \u0026vrp-\u003evdev-\u003edev;\ndrivers/rpmsg/virtio_rpmsg_bus.c:426:\trpdev-\u003edev.release = virtio_rpmsg_release_device;\ndrivers/rpmsg/virtio_rpmsg_bus.c-427-\tret = rpmsg_register_device(rpdev);\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=491=static int rpmsg_send_offchannel_raw(struct rpmsg_device rpdev,\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-494-{\ndrivers/rpmsg/virtio_rpmsg_bus.c:495:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-496-\tstruct virtproc_info vrp = vch-\u003evrp;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-582-\ndrivers/rpmsg/virtio_rpmsg_bus.c:583:static int virtio_rpmsg_send(struct rpmsg_endpoint ept, const void data, int len)\ndrivers/rpmsg/virtio_rpmsg_bus.c-584-{\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-590-\ndrivers/rpmsg/virtio_rpmsg_bus.c:591:static int virtio_rpmsg_sendto(struct rpmsg_endpoint ept, const void data,\ndrivers/rpmsg/virtio_rpmsg_bus.c-592-\t\t\t int len, u32 dst)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-599-\ndrivers/rpmsg/virtio_rpmsg_bus.c:600:static int virtio_rpmsg_trysend(struct rpmsg_endpoint ept, const void data,\ndrivers/rpmsg/virtio_rpmsg_bus.c-601-\t\t\t\tint len)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-608-\ndrivers/rpmsg/virtio_rpmsg_bus.c:609:static int virtio_rpmsg_trysendto(struct rpmsg_endpoint ept, const void data,\ndrivers/rpmsg/virtio_rpmsg_bus.c-610-\t\t\t\t int len, u32 dst)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-617-\ndrivers/rpmsg/virtio_rpmsg_bus.c:618:static __poll_t virtio_rpmsg_poll(struct rpmsg_endpoint ept, struct file filp,\ndrivers/rpmsg/virtio_rpmsg_bus.c-619-\t\t\t\t poll_table wait)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-621-\tstruct rpmsg_device rpdev = ept-\u003erpdev;\ndrivers/rpmsg/virtio_rpmsg_bus.c:622:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-623-\tstruct virtproc_info vrp = vch-\u003evrp;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-645-\ndrivers/rpmsg/virtio_rpmsg_bus.c:646:static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint ept)\ndrivers/rpmsg/virtio_rpmsg_bus.c-647-{\ndrivers/rpmsg/virtio_rpmsg_bus.c-648-\tstruct rpmsg_device rpdev = ept-\u003erpdev;\ndrivers/rpmsg/virtio_rpmsg_bus.c:649:\tstruct virtio_rpmsg_channel vch = to_virtio_rpmsg_channel(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-650-\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=776=static struct rpmsg_device rpmsg_virtio_add_ctrl_dev(struct virtio_device vdev)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-778-\tstruct virtproc_info vrp = vdev-\u003epriv;\ndrivers/rpmsg/virtio_rpmsg_bus.c:779:\tstruct virtio_rpmsg_channel vch;\ndrivers/rpmsg/virtio_rpmsg_bus.c-780-\tstruct rpmsg_device rpdev_ctrl;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-791-\trpdev_ctrl = \u0026vch-\u003erpdev;\ndrivers/rpmsg/virtio_rpmsg_bus.c:792:\trpdev_ctrl-\u003eops = \u0026virtio_rpmsg_ops;\ndrivers/rpmsg/virtio_rpmsg_bus.c-793-\ndrivers/rpmsg/virtio_rpmsg_bus.c-794-\trpdev_ctrl-\u003edev.parent = \u0026vrp-\u003evdev-\u003edev;\ndrivers/rpmsg/virtio_rpmsg_bus.c:795:\trpdev_ctrl-\u003edev.release = virtio_rpmsg_release_device;\ndrivers/rpmsg/virtio_rpmsg_bus.c-796-\trpdev_ctrl-\u003elittle_endian = virtio_is_little_endian(vrp-\u003evdev);\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-799-\tif (err) {\ndrivers/rpmsg/virtio_rpmsg_bus.c:800:\t\t/* vch will be free in virtio_rpmsg_release_device() /\ndrivers/rpmsg/virtio_rpmsg_bus.c-801-\t\treturn ERR_PTR(err);\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=814=static int rpmsg_probe(struct virtio_device vdev)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-821-\tstruct virtproc_info vrp;\ndrivers/rpmsg/virtio_rpmsg_bus.c:822:\tstruct virtio_rpmsg_channel vch = NULL;\ndrivers/rpmsg/virtio_rpmsg_bus.c-823-\tstruct rpmsg_device rpdev_ns, rpdev_ctrl;\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-912-\t\trpdev_ns = \u0026vch-\u003erpdev;\ndrivers/rpmsg/virtio_rpmsg_bus.c:913:\t\trpdev_ns-\u003eops = \u0026virtio_rpmsg_ops;\ndrivers/rpmsg/virtio_rpmsg_bus.c-914-\t\trpdev_ns-\u003elittle_endian = virtio_is_little_endian(vrp-\u003evdev);\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-916-\t\trpdev_ns-\u003edev.parent = \u0026vrp-\u003evdev-\u003edev;\ndrivers/rpmsg/virtio_rpmsg_bus.c:917:\t\trpdev_ns-\u003edev.release = virtio_rpmsg_release_device;\ndrivers/rpmsg/virtio_rpmsg_bus.c-918-\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-920-\t\tif (err)\ndrivers/rpmsg/virtio_rpmsg_bus.c:921:\t\t\t/* vch will be free in virtio_rpmsg_release_device() */\ndrivers/rpmsg/virtio_rpmsg_bus.c-922-\t\t\tgoto free_ctrldev;\n" }
23/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19906 output: 42 thoughts: 52 Thoughts: Okay, let's dive into this. I need to figure out what's going on with the virtio ID `virtio_rpmsg_bus`. Where does this get bound? Time to dig into the code. Investigating the `virtio_rpmsg_bus` Binding Alright, I'm going to jump into the `drivers/rpmsg/virtio_rpmsg_bus.c` file. Specifically, I'm focusing on lines 950 through 1010. This is probably where the core binding logic resides. I'll need to carefully parse that section to understand the device matching and probe procedures. I'm looking for clues about how this specific ID is recognized and handled within the VirtIO framework and see how it interacts with the underlying RPMSG messaging system. This should give me the answer I need.
24/2	2026/10/26 11:46	tool	read-file	0m Args: { "File": "drivers/rpmsg/virtio_rpmsg_bus.c", "FirstLine": 950, "LineCount": 60 } Results: { "Contents": " 950:\t\t\t\t bufs_va, vrp-\u003ebufs_dma);\n 951:\tvqs_del:\n 952:\t\tvdev-\u003econfig-\u003edel_vqs(vrp-\u003evdev);\n 953:\tfree_vrp:\n 954:\t\tkfree(vrp);\n 955:\t\treturn err;\n 956:\t}\n 957:\t\n 958:\tstatic int rpmsg_remove_device(struct device dev, void data)\n 959:\t{\n 960:\t\tdevice_unregister(dev);\n 961:\t\n 962:\t\treturn 0;\n 963:\t}\n 964:\t\n 965:\tstatic void rpmsg_remove(struct virtio_device vdev)\n 966:\t{\n 967:\t\tstruct virtproc_info vrp = vdev-\u003epriv;\n 968:\t\tsize_t total_buf_space = vrp-\u003enum_bufs * vrp-\u003ebuf_size;\n 969:\t\tint ret;\n 970:\t\n 971:\t\tvirtio_reset_device(vdev);\n 972:\t\n 973:\t\tret = device_for_each_child(\u0026vdev-\u003edev, NULL, rpmsg_remove_device);\n 974:\t\tif (ret)\n 975:\t\t\tdev_warn(\u0026vdev-\u003edev, \"can't remove rpmsg device: %d\\n\", ret);\n 976:\t\n 977:\t\tidr_destroy(\u0026vrp-\u003eendpoints);\n 978:\t\n 979:\t\tvdev-\u003econfig-\u003edel_vqs(vrp-\u003evdev);\n 980:\t\n 981:\t\tdma_free_coherent(vdev-\u003edev.parent, total_buf_space,\n 982:\t\t\t\t vrp-\u003erbufs, vrp-\u003ebufs_dma);\n 983:\t\n 984:\t\tkfree(vrp);\n 985:\t}\n 986:\t\n 987:\tstatic struct virtio_device_id id_table[] = {\n 988:\t\t{ VIRTIO_ID_RPMSG, VIRTIO_DEV_ANY_ID },\n 989:\t\t{ 0 },\n 990:\t};\n 991:\t\n 992:\tstatic unsigned int features[] = {\n 993:\t\tVIRTIO_RPMSG_F_NS,\n 994:\t};\n 995:\t\n 996:\tstatic struct virtio_driver virtio_ipc_driver = {\n 997:\t\t.feature_table\t= features,\n 998:\t\t.feature_table_size = ARRAY_SIZE(features),\n 999:\t\t.driver.name\t= KBUILD_MODNAME,\n1000:\t\t.id_table\t= id_table,\n1001:\t\t.probe\t\t= rpmsg_probe,\n1002:\t\t.remove\t\t= rpmsg_remove,\n1003:\t};\n1004:\t\n1005:\tstatic int __init rpmsg_init(void)\n1006:\t{\n1007:\t\tint ret;\n1008:\t\n1009:\t\tret = register_virtio_driver(\u0026virtio_ipc_driver);\n" }
25/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 21046 output: 20 thoughts: 495 Thoughts: My Investigation into Virtio-RPMSG Device Instantiation Okay, so `virtio_ipc_driver` is registered, which tells me it's responsible for handling RPMSG over virtio. It binds to `VIRTIO_ID_RPMSG` – that's 7. My mind immediately jumps to the question of how these virtio devices are created or emulated. Can I instantiate them in something like QEMU, virtio-uml, or even using syzkaller? The key question then becomes: what specifically does syzkaller support? Does it even touch RPMSG, or even more specifically, the virtualized drivers for rpmsg? Can syzkaller open `/dev/rpmsg` or `rpmsg_ctrl`? I need to understand the initial conditions. The big question is how do I instantiate a virtio-rpmsg device in the first place. Does QEMU, in its standard configuration, emulate `VIRTIO_ID_RPMSG`? My memory is failing me. No, standard QEMU doesn't have a specific `virtio-rpmsg-pci` device by default. Or does it? That's a point of uncertainty! What about alternatives like vhost-user, virtio-pci, or virtio-mmio? My core issue is: Is RPMSG something fundamentally hardware-bound or are there alternative ways to create these devices virtually? I need to examine Syzkaller as a resource to explore this question. I want to see if rpmsg is present in syzkaller. I can't search syzkaller syzlang descriptions, so that's out. I check my available tools: grepper, codesearch-dir-index, read-file, and set-results. I can't use `syz-grepper` or `read-syz-spec`, because those tools are not present. So, I need to methodically check the kernel sources, starting with how RPMSG devices are created or probed. I'll search for things like `register_rpmsg_driver`, `rpmsg_register_device`, or the string "RPMSG" within the `drivers/` directory to understand how these devices are handled in the kernel. This is where I start.
26/2	2026/10/26 11:46	tool	grepper	0m Args: { "Expression": "rpmsg_register_device" } Results: { "Output": "drivers/rpmsg/mtk_rpmsg.c=179=mtk_rpmsg_match_device_subnode(struct device_node node, const char channel)\n--\ndrivers/rpmsg/mtk_rpmsg.c-196-\ndrivers/rpmsg/mtk_rpmsg.c:197:static int mtk_rpmsg_register_device(struct mtk_rpmsg_rproc_subdev mtk_subdev,\ndrivers/rpmsg/mtk_rpmsg.c-198-\t\t\t\t struct rpmsg_channel_info info)\n--\ndrivers/rpmsg/mtk_rpmsg.c-220-\ndrivers/rpmsg/mtk_rpmsg.c:221:\treturn rpmsg_register_device(rpdev);\ndrivers/rpmsg/mtk_rpmsg.c-222-}\n--\ndrivers/rpmsg/mtk_rpmsg.c=224=static void mtk_register_device_work_function(struct work_struct register_work)\n--\ndrivers/rpmsg/mtk_rpmsg.c-237-\t\tmutex_unlock(\u0026subdev-\u003echannels_lock);\ndrivers/rpmsg/mtk_rpmsg.c:238:\t\tret = mtk_rpmsg_register_device(subdev, \u0026info-\u003einfo);\ndrivers/rpmsg/mtk_rpmsg.c-239-\t\tmutex_lock(\u0026subdev-\u003echannels_lock);\n--\ndrivers/rpmsg/qcom_glink_native.c=1629=static int qcom_glink_rx_open(struct qcom_glink glink, unsigned int rcid,\n--\ndrivers/rpmsg/qcom_glink_native.c-1687-\ndrivers/rpmsg/qcom_glink_native.c:1688:\t\tret = rpmsg_register_device(rpdev);\ndrivers/rpmsg/qcom_glink_native.c-1689-\t\tif (ret)\n--\ndrivers/rpmsg/qcom_smd.c=1074=static int qcom_smd_create_device(struct qcom_smd_channel channel)\n--\ndrivers/rpmsg/qcom_smd.c-1101-\ndrivers/rpmsg/qcom_smd.c:1102:\treturn rpmsg_register_device(rpdev);\ndrivers/rpmsg/qcom_smd.c-1103-}\n--\ndrivers/rpmsg/rpmsg_core.c=508=static const struct bus_type rpmsg_bus = {\n--\ndrivers/rpmsg/rpmsg_core.c-519- A helper for registering rpmsg device with driver override and name.\ndrivers/rpmsg/rpmsg_core.c:520: * Drivers should not be using it, but instead rpmsg_register_device().\ndrivers/rpmsg/rpmsg_core.c-521- /\ndrivers/rpmsg/rpmsg_core.c:522:int rpmsg_register_device_override(struct rpmsg_device rpdev,\ndrivers/rpmsg/rpmsg_core.c-523-\t\t\t\t const char driver_override)\n--\ndrivers/rpmsg/rpmsg_core.c-553-}\ndrivers/rpmsg/rpmsg_core.c:554:EXPORT_SYMBOL(rpmsg_register_device_override);\ndrivers/rpmsg/rpmsg_core.c-555-\ndrivers/rpmsg/rpmsg_core.c:556:int rpmsg_register_device(struct rpmsg_device rpdev)\ndrivers/rpmsg/rpmsg_core.c-557-{\ndrivers/rpmsg/rpmsg_core.c:558:\treturn rpmsg_register_device_override(rpdev, NULL);\ndrivers/rpmsg/rpmsg_core.c-559-}\ndrivers/rpmsg/rpmsg_core.c:560:EXPORT_SYMBOL(rpmsg_register_device);\ndrivers/rpmsg/rpmsg_core.c-561-\n--\ndrivers/rpmsg/rpmsg_internal.h=82=int rpmsg_release_channel(struct rpmsg_device rpdev,\n--\ndrivers/rpmsg/rpmsg_internal.h-87- \ndrivers/rpmsg/rpmsg_internal.h:88: * This function wraps rpmsg_register_device() preparing the rpdev for use as\ndrivers/rpmsg/rpmsg_internal.h-89- * basis for the rpmsg chrdev.\n--\ndrivers/rpmsg/rpmsg_internal.h=91=static inline int rpmsg_ctrldev_register_device(struct rpmsg_device rpdev)\ndrivers/rpmsg/rpmsg_internal.h-92-{\ndrivers/rpmsg/rpmsg_internal.h:93:\treturn rpmsg_register_device_override(rpdev, \"rpmsg_ctrl\");\ndrivers/rpmsg/rpmsg_internal.h-94-}\n--\ndrivers/rpmsg/rpmsg_ns.c-17- \ndrivers/rpmsg/rpmsg_ns.c:18: * This function wraps rpmsg_register_device() preparing the rpdev for use as\ndrivers/rpmsg/rpmsg_ns.c-19- * basis for the rpmsg name service device.\n--\ndrivers/rpmsg/rpmsg_ns.c=21=int rpmsg_ns_register_device(struct rpmsg_device rpdev)\n--\ndrivers/rpmsg/rpmsg_ns.c-25-\ndrivers/rpmsg/rpmsg_ns.c:26:\treturn rpmsg_register_device_override(rpdev, \"rpmsg_ns\");\ndrivers/rpmsg/rpmsg_ns.c-27-}\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=385=static struct rpmsg_device __rpmsg_create_channel(struct virtproc_info vrp,\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-426-\trpdev-\u003edev.release = virtio_rpmsg_release_device;\ndrivers/rpmsg/virtio_rpmsg_bus.c:427:\tret = rpmsg_register_device(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-428-\tif (ret)\n--\ninclude/linux/rpmsg.h=159=static inline __rpmsg64 cpu_to_rpmsg64(struct rpmsg_device rpdev, u64 val)\n--\ninclude/linux/rpmsg.h-168-\ninclude/linux/rpmsg.h:169:int rpmsg_register_device_override(struct rpmsg_device rpdev,\ninclude/linux/rpmsg.h-170-\t\t\t\t const char driver_override);\ninclude/linux/rpmsg.h:171:int rpmsg_register_device(struct rpmsg_device rpdev);\ninclude/linux/rpmsg.h-172-int rpmsg_unregister_device(struct device parent,\n--\ninclude/linux/rpmsg.h=192=int rpmsg_set_flow_control(struct rpmsg_endpoint ept, bool pause, u32 dst);\n--\ninclude/linux/rpmsg.h-195-\ninclude/linux/rpmsg.h:196:static inline int rpmsg_register_device_override(struct rpmsg_device rpdev,\ninclude/linux/rpmsg.h-197-\t\t\t\t\t\t const char driver_override)\n--\ninclude/linux/rpmsg.h-201-\ninclude/linux/rpmsg.h:202:static inline int rpmsg_register_device(struct rpmsg_device rpdev)\ninclude/linux/rpmsg.h-203-{\n" }
27/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23961 output: 24 thoughts: 32 Thoughts: Okay, here's my interpretation of those thoughts, crafted for an expert audience, presented in the first person: Investigating RPMSG Driver Registration Right, let's get down to brass tacks. I need to understand which drivers are involved in the registration process for rpdev or rpmsg devices. The most direct approach, as always, is to delve into the code. My hunch is that the crucial function to pinpoint is `rpmsg_ctrldev_register_device`. Finding the callers of this function will give me a clear picture of the actors in this game. I'll start with a targeted search and see what comes up. This should quickly illuminate the driver ecosystem I'm looking for.
28/2	2026/10/26 11:46	tool	grepper	0m Args: { "Expression": "rpmsg_ctrldev_register_device" } Results: { "Output": "drivers/rpmsg/qcom_glink_native.c=1864=static int qcom_glink_create_chrdev(struct qcom_glink glink)\n--\ndrivers/rpmsg/qcom_glink_native.c-1884-\ndrivers/rpmsg/qcom_glink_native.c:1885:\treturn rpmsg_ctrldev_register_device(rpdev);\ndrivers/rpmsg/qcom_glink_native.c-1886-}\n--\ndrivers/rpmsg/qcom_smd.c=1105=static int qcom_smd_create_chrdev(struct qcom_smd_edge edge)\n--\ndrivers/rpmsg/qcom_smd.c-1117-\ndrivers/rpmsg/qcom_smd.c:1118:\treturn rpmsg_ctrldev_register_device(\u0026qsdev-\u003erpdev);\ndrivers/rpmsg/qcom_smd.c-1119-}\n--\ndrivers/rpmsg/rpmsg_internal.h=82=int rpmsg_release_channel(struct rpmsg_device rpdev,\n--\ndrivers/rpmsg/rpmsg_internal.h-84-/\ndrivers/rpmsg/rpmsg_internal.h:85: rpmsg_ctrldev_register_device() - register a char device for control based on rpdev\ndrivers/rpmsg/rpmsg_internal.h-86- * @rpdev:\tprepared rpdev to be used for creating endpoints\n--\ndrivers/rpmsg/rpmsg_internal.h-90- /\ndrivers/rpmsg/rpmsg_internal.h:91:static inline int rpmsg_ctrldev_register_device(struct rpmsg_device rpdev)\ndrivers/rpmsg/rpmsg_internal.h-92-{\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=776=static struct rpmsg_device rpmsg_virtio_add_ctrl_dev(struct virtio_device vdev)\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-797-\ndrivers/rpmsg/virtio_rpmsg_bus.c:798:\terr = rpmsg_ctrldev_register_device(rpdev_ctrl);\ndrivers/rpmsg/virtio_rpmsg_bus.c-799-\tif (err) {\n" }
29/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 24761 output: 38 thoughts: 29 Thoughts: Okay, here's my interpretation of that thought process, assuming I'm already quite familiar with embedded systems, remote procedure calls, and likely using the Linux kernel as a reference: Diving into the Rpmsg Control Structure Alright, let's get down to brass tacks. I need to understand the control mechanism of the Remote Processor Messaging (Rpmsg) system. I know Rpmsg provides a framework for inter-processor communication, but I want to see exactly how the control plane is managed. My focus right now is specifically the `rpmsg_ctrl` component. I'm going to navigate to `drivers/rpmsg/rpmsg_ctrl.c` in the kernel source. Time to dig in and see how the control channel is established, how it's used for device discovery and management, and what data structures are at play. I'm looking for the core logic, how messages are routed, and the interaction with the underlying hardware communication drivers. Let's see how this thing really works.
30/2	2026/10/26 11:46	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_ctrl.c", "FirstLine": 1, "LineCount": 100 } Results: { "Contents": " 1:\t// SPDX-License-Identifier: GPL-2.0\n 2:\t/\n 3:\t Copyright (C) 2022, STMicroelectronics\n 4:\t * Copyright (c) 2016, Linaro Ltd.\n 5:\t * Copyright (c) 2012, Michal Simek \u003cmonstr@monstr.eu\u003e\n 6:\t * Copyright (c) 2012, PetaLogix\n 7:\t * Copyright (c) 2011, Texas Instruments, Inc.\n 8:\t * Copyright (c) 2011, Google, Inc.\n 9:\t \n 10:\t Based on rpmsg performance statistics driver by Michal Simek, which in turn\n 11:\t * was based on TI \u0026 Google OMX rpmsg driver.\n 12:\t /\n 13:\t\n 14:\t#define pr_fmt(fmt)\t\tKBUILD_MODNAME \": \" fmt\n 15:\t\n 16:\t#include \u003clinux/cdev.h\u003e\n 17:\t#include \u003clinux/device.h\u003e\n 18:\t#include \u003clinux/fs.h\u003e\n 19:\t#include \u003clinux/idr.h\u003e\n 20:\t#include \u003clinux/kernel.h\u003e\n 21:\t#include \u003clinux/module.h\u003e\n 22:\t#include \u003clinux/rpmsg.h\u003e\n 23:\t#include \u003clinux/skbuff.h\u003e\n 24:\t#include \u003clinux/slab.h\u003e\n 25:\t#include \u003clinux/uaccess.h\u003e\n 26:\t#include \u003cuapi/linux/rpmsg.h\u003e\n 27:\t\n 28:\t#include \"rpmsg_char.h\"\n 29:\t#include \"rpmsg_internal.h\"\n 30:\t\n 31:\t#define RPMSG_DEV_MAX\t(MINORMASK + 1)\n 32:\t\n 33:\tstatic dev_t rpmsg_major;\n 34:\t\n 35:\tstatic DEFINE_IDA(rpmsg_ctrl_ida);\n 36:\tstatic DEFINE_IDA(rpmsg_minor_ida);\n 37:\t\n 38:\t#define dev_to_ctrldev(dev) container_of(dev, struct rpmsg_ctrldev, dev)\n 39:\t#define cdev_to_ctrldev(i_cdev) container_of(i_cdev, struct rpmsg_ctrldev, cdev)\n 40:\t\n 41:\t/\n 42:\t struct rpmsg_ctrldev - control device for instantiating endpoint devices\n 43:\t * @rpdev:\tunderlaying rpmsg device\n 44:\t * @cdev:\tcdev for the ctrl device\n 45:\t * @dev:\tdevice for the ctrl device\n 46:\t * @ctrl_lock:\tserialize the ioctrls.\n 47:\t /\n 48:\tstruct rpmsg_ctrldev {\n 49:\t\tstruct rpmsg_device rpdev;\n 50:\t\tstruct cdev cdev;\n 51:\t\tstruct device dev;\n 52:\t\tstruct mutex ctrl_lock;\n 53:\t};\n 54:\t\n 55:\tstatic int rpmsg_ctrldev_open(struct inode inode, struct file filp)\n 56:\t{\n 57:\t\tstruct rpmsg_ctrldev ctrldev = cdev_to_ctrldev(inode-\u003ei_cdev);\n 58:\t\n 59:\t\tget_device(\u0026ctrldev-\u003edev);\n 60:\t\tfilp-\u003eprivate_data = ctrldev;\n 61:\t\n 62:\t\treturn 0;\n 63:\t}\n 64:\t\n 65:\tstatic int rpmsg_ctrldev_release(struct inode inode, struct file filp)\n 66:\t{\n 67:\t\tstruct rpmsg_ctrldev ctrldev = cdev_to_ctrldev(inode-\u003ei_cdev);\n 68:\t\n 69:\t\tput_device(\u0026ctrldev-\u003edev);\n 70:\t\n 71:\t\treturn 0;\n 72:\t}\n 73:\t\n 74:\tstatic long rpmsg_ctrldev_ioctl(struct file fp, unsigned int cmd,\n 75:\t\t\t\t\tunsigned long arg)\n 76:\t{\n 77:\t\tstruct rpmsg_ctrldev ctrldev = fp-\u003eprivate_data;\n 78:\t\tvoid __user argp = (void __user )arg;\n 79:\t\tstruct rpmsg_endpoint_info eptinfo;\n 80:\t\tstruct rpmsg_channel_info chinfo;\n 81:\t\tstruct rpmsg_device *rpdev;\n 82:\t\tint ret = 0;\n 83:\t\n 84:\t\tif (copy_from_user(\u0026eptinfo, argp, sizeof(eptinfo)))\n 85:\t\t\treturn -EFAULT;\n 86:\t\n 87:\t\tmemcpy(chinfo.name, eptinfo.name, RPMSG_NAME_SIZE);\n 88:\t\tchinfo.name[RPMSG_NAME_SIZE - 1] = '\\0';\n 89:\t\tchinfo.src = eptinfo.src;\n 90:\t\tchinfo.dst = eptinfo.dst;\n 91:\t\n 92:\t\tmutex_lock(\u0026ctrldev-\u003ectrl_lock);\n 93:\t\tswitch (cmd) {\n 94:\t\tcase RPMSG_CREATE_EPT_IOCTL:\n 95:\t\t\tret = rpmsg_chrdev_eptdev_create(ctrldev-\u003erpdev, \u0026ctrldev-\u003edev, chinfo);\n 96:\t\t\tbreak;\n 97:\t\n 98:\t\tcase RPMSG_CREATE_DEV_IOCTL:\n 99:\t\t\trpdev = rpmsg_create_channel(ctrldev-\u003erpdev, \u0026chinfo);\n 100:\t\t\tif (!rpdev) {\n" }
31/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26568 output: 22 thoughts: 420 Thoughts: My RPMSG Device Investigation Okay, let's break this down. First, `rpmsg_ctrldev_ioctl` creates the `/dev/rpmsgX` endpoint device, handled by `RPMSG_CREATE_EPT_IOCTL` and `rpmsg_chrdev_eptdev_create`. Then, when I open `/dev/rpmsgX`, it's the `rpmsg_eptdev_fops` that come into play, specifically `rpmsg_eptdev_ioctl`. That's where the magic happens. Let's look at what `rpmsg_eptdev_ioctl` does... ah, flow control! I see `RPMSG_SET_INCOMING_FLOWCONTROL` allows setting the incoming flow control via a mutex-protected call to `rpmsg_set_flow_control`, assuming the endpoint (`eptdev->ept`) is valid. Now, my real question: how can I actually use an rpmsg device on an x86/amd64 system running Linux in QEMU/KVM? That's what I want to figure out. The key is in instantiating it. Can I actually get an rpmsg device on an x86/amd64 setup? Hold on, wait a second. Can I get a virtio-rpmsg device? or even any rpmsg device at all? Or perhaps a remoteproc driver is suitable? Or maybe there's some kind of test driver or virtio setup I can use? Wait. Can QEMU even emulate `VIRTIO_ID_RPMSG`? That's the pivotal question. I need to know if QEMU provides the necessary hardware emulation. Right, gotta check `include/uapi/linux/virtio_ids.h` to see what virtio device IDs are supported. That will give me the answer.
32/2	2026/10/26 11:46	tool	grepper	0m Args: { "Expression": "VIRTIO_ID_RPMSG" } Results: { "Output": "drivers/rpmsg/virtio_rpmsg_bus.c=987=static struct virtio_device_id id_table[] = {\ndrivers/rpmsg/virtio_rpmsg_bus.c:988:\t{ VIRTIO_ID_RPMSG, VIRTIO_DEV_ANY_ID },\ndrivers/rpmsg/virtio_rpmsg_bus.c-989-\t{ 0 },\n--\ninclude/uapi/linux/virtio_ids.h-37-#define VIRTIO_ID_IOMEM\t\t\t6 /* virtio ioMemory /\ninclude/uapi/linux/virtio_ids.h:38:#define VIRTIO_ID_RPMSG\t\t\t7 / virtio remote processor messaging /\ninclude/uapi/linux/virtio_ids.h-39-#define VIRTIO_ID_SCSI\t\t\t8 / virtio scsi */\n" }
33/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 27634 output: 22 thoughts: 53 Thoughts: Okay, let's dive into this. Here's how I'd approach this task: Investigating Virtio RPMSG Kernel Driver Instantiation Right, so I need to understand which drivers in the Linux kernel are responsible for bringing up Virtio RPMSG devices, or more generally, for creating an rpmsg device, right? That's the crux of this. My first step is clear: I need to do a thorough code search. I'm going to start by looking for the `VIRTIO_ID_RPMSG` constant throughout the entire kernel source tree. This constant, of course, serves as the defining identifier for the specific Virtio device class we're interested in. The purpose is to identify all the places where this ID is used, which should lead me directly to the drivers that register or handle these RPMSG-specific Virtio devices. I'm expecting this initial search to turn up the relevant driver files, and potentially some helper functions related to rpmsg device creation or handling within the virtio framework.
34/2	2026/10/26 11:46	tool	grepper	0m Args: { "Expression": "VIRTIO_ID_RPMSG" } Results: { "Output": "drivers/rpmsg/virtio_rpmsg_bus.c=987=static struct virtio_device_id id_table[] = {\ndrivers/rpmsg/virtio_rpmsg_bus.c:988:\t{ VIRTIO_ID_RPMSG, VIRTIO_DEV_ANY_ID },\ndrivers/rpmsg/virtio_rpmsg_bus.c-989-\t{ 0 },\n--\ninclude/uapi/linux/virtio_ids.h-37-#define VIRTIO_ID_IOMEM\t\t\t6 /* virtio ioMemory /\ninclude/uapi/linux/virtio_ids.h:38:#define VIRTIO_ID_RPMSG\t\t\t7 / virtio remote processor messaging /\ninclude/uapi/linux/virtio_ids.h-39-#define VIRTIO_ID_SCSI\t\t\t8 / virtio scsi */\n" }
35/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 28146 output: 43 thoughts: 49 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Remoteproc and Virtio RPMSG Device Creation Alright, so I'm thinking about the mechanics of how `remoteproc` interacts with the `virtio-rpmsg` device driver. The question that's rattling around in my head is, specifically, where does the magic happen? Where does the `remoteproc` framework actually instantiate or register these `virtio-rpmsg` devices? I need to drill down into the code to trace this. My initial approach is to go straight for the jugular – let's search the `drivers/remoteproc` directory. I'll target either `remoteproc_virtio` or `rproc_add_virtio_dev` as keywords, since those are the most likely candidates for the relevant functions or variables responsible. I'm expecting to find either a dedicated function that handles this integration or, perhaps, a part of a larger initialization sequence that includes `virtio-rpmsg` device addition. I'm leaning towards a dedicated function, it would make sense for the code to be modular.
36/2	2026/10/26 11:46	tool	grepper	0m Args: { "Expression": "rproc_add_virtio_dev\|rproc_vdev", "PathPrefixes": [ "drivers/remoteproc/" ] } Results: { "Output": "drivers/remoteproc/imx_dsp_rproc.c=654=static int imx_dsp_rproc_add_carveout(struct imx_dsp_rproc priv)\n--\ndrivers/remoteproc/imx_dsp_rproc.c-699-\t\t Ignore the first memory region which will be used vdev buffer.\ndrivers/remoteproc/imx_dsp_rproc.c:700:\t\t * No need to do extra handlings, rproc_add_virtio_dev will handle it.\ndrivers/remoteproc/imx_dsp_rproc.c-701-\t\t /\n--\ndrivers/remoteproc/imx_rproc.c=633=static int imx_rproc_prepare(struct rproc rproc)\n--\ndrivers/remoteproc/imx_rproc.c-651-\t\t * Ignore the first memory region which will be used vdev buffer.\ndrivers/remoteproc/imx_rproc.c:652:\t\t * No need to do extra handlings, rproc_add_virtio_dev will handle it.\ndrivers/remoteproc/imx_rproc.c-653-\t\t /\n--\ndrivers/remoteproc/remoteproc_core.c=286=static int rproc_check_carveout_da(struct rproc rproc,\n--\ndrivers/remoteproc/remoteproc_core.c-320-\ndrivers/remoteproc/remoteproc_core.c:321:int rproc_alloc_vring(struct rproc_vdev rvdev, int i)\ndrivers/remoteproc/remoteproc_core.c-322-{\n--\ndrivers/remoteproc/remoteproc_core.c=381=int\ndrivers/remoteproc/remoteproc_core.c:382:rproc_parse_vring(struct rproc_vdev rvdev, struct fw_rsc_vdev rsc, int i)\ndrivers/remoteproc/remoteproc_core.c-383-{\n--\ndrivers/remoteproc/remoteproc_core.c=406=void rproc_free_vring(struct rproc_vring rvring)\n--\ndrivers/remoteproc/remoteproc_core.c-431-\ndrivers/remoteproc/remoteproc_core.c:432:void rproc_add_rvdev(struct rproc rproc, struct rproc_vdev rvdev)\ndrivers/remoteproc/remoteproc_core.c-433-{\n--\ndrivers/remoteproc/remoteproc_core.c-437-\ndrivers/remoteproc/remoteproc_core.c:438:void rproc_remove_rvdev(struct rproc_vdev rvdev)\ndrivers/remoteproc/remoteproc_core.c-439-{\n--\ndrivers/remoteproc/remoteproc_core.c=471=static int rproc_handle_vdev(struct rproc rproc, void ptr,\n--\ndrivers/remoteproc/remoteproc_core.c-475-\tstruct device dev = \u0026rproc-\u003edev;\ndrivers/remoteproc/remoteproc_core.c:476:\tstruct rproc_vdev rvdev;\ndrivers/remoteproc/remoteproc_core.c-477-\tsize_t rsc_size;\ndrivers/remoteproc/remoteproc_core.c:478:\tstruct rproc_vdev_data rvdev_data;\ndrivers/remoteproc/remoteproc_core.c-479-\tstruct platform_device pdev;\n--\ndrivers/remoteproc/remoteproc_core.c=1218=void rproc_resource_cleanup(struct rproc rproc)\n--\ndrivers/remoteproc/remoteproc_core.c-1221-\tstruct rproc_debug_trace trace, ttmp;\ndrivers/remoteproc/remoteproc_core.c:1222:\tstruct rproc_vdev rvdev, rvtmp;\ndrivers/remoteproc/remoteproc_core.c-1223-\tstruct device dev = \u0026rproc-\u003edev;\n--\ndrivers/remoteproc/remoteproc_internal.h=23=struct rproc_debug_trace {\n--\ndrivers/remoteproc/remoteproc_internal.h-30-/*\ndrivers/remoteproc/remoteproc_internal.h:31: struct rproc_vdev_data - remoteproc virtio device data\ndrivers/remoteproc/remoteproc_internal.h-32- * @rsc_offset: offset of the vdev's resource entry\n--\ndrivers/remoteproc/remoteproc_internal.h-37- /\ndrivers/remoteproc/remoteproc_internal.h:38:struct rproc_vdev_data {\ndrivers/remoteproc/remoteproc_internal.h-39-\tu32 rsc_offset;\n--\ndrivers/remoteproc/remoteproc_internal.h=110=void rproc_free_vring(struct rproc_vring rvring);\ndrivers/remoteproc/remoteproc_internal.h:111:int rproc_alloc_vring(struct rproc_vdev rvdev, int i);\ndrivers/remoteproc/remoteproc_internal.h:112:int rproc_parse_vring(struct rproc_vdev rvdev, struct fw_rsc_vdev rsc, int i);\ndrivers/remoteproc/remoteproc_internal.h-113-\n--\ndrivers/remoteproc/remoteproc_internal.h=124=rproc_find_carveout_by_name(struct rproc rproc, const char name, ...);\ndrivers/remoteproc/remoteproc_internal.h:125:void rproc_add_rvdev(struct rproc rproc, struct rproc_vdev rvdev);\ndrivers/remoteproc/remoteproc_internal.h:126:void rproc_remove_rvdev(struct rproc_vdev rvdev);\ndrivers/remoteproc/remoteproc_internal.h-127-\n--\ndrivers/remoteproc/remoteproc_virtio.c=30=static int copy_dma_range_map(struct device to, struct device from)\n--\ndrivers/remoteproc/remoteproc_virtio.c-48-\ndrivers/remoteproc/remoteproc_virtio.c:49:static struct rproc_vdev vdev_to_rvdev(struct virtio_device vdev)\ndrivers/remoteproc/remoteproc_virtio.c-50-{\n--\ndrivers/remoteproc/remoteproc_virtio.c=58=static struct rproc vdev_to_rproc(struct virtio_device vdev)\ndrivers/remoteproc/remoteproc_virtio.c-59-{\ndrivers/remoteproc/remoteproc_virtio.c:60:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-61-\n--\ndrivers/remoteproc/remoteproc_virtio.c=112=static struct virtqueue rp_find_vq(struct virtio_device vdev,\n--\ndrivers/remoteproc/remoteproc_virtio.c-116-{\ndrivers/remoteproc/remoteproc_virtio.c:117:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-118-\tstruct rproc rproc = vdev_to_rproc(vdev);\n--\ndrivers/remoteproc/remoteproc_virtio.c=228=static u8 rproc_virtio_get_status(struct virtio_device vdev)\ndrivers/remoteproc/remoteproc_virtio.c-229-{\ndrivers/remoteproc/remoteproc_virtio.c:230:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-231-\tstruct fw_rsc_vdev rsc;\n--\ndrivers/remoteproc/remoteproc_virtio.c=238=static void rproc_virtio_set_status(struct virtio_device vdev, u8 status)\ndrivers/remoteproc/remoteproc_virtio.c-239-{\ndrivers/remoteproc/remoteproc_virtio.c:240:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-241-\tstruct fw_rsc_vdev rsc;\n--\ndrivers/remoteproc/remoteproc_virtio.c=249=static void rproc_virtio_reset(struct virtio_device vdev)\ndrivers/remoteproc/remoteproc_virtio.c-250-{\ndrivers/remoteproc/remoteproc_virtio.c:251:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-252-\tstruct fw_rsc_vdev rsc;\n--\ndrivers/remoteproc/remoteproc_virtio.c=268=static u64 rproc_virtio_get_features(struct virtio_device vdev)\ndrivers/remoteproc/remoteproc_virtio.c-269-{\ndrivers/remoteproc/remoteproc_virtio.c:270:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-271-\tstruct fw_rsc_vdev rsc;\n--\ndrivers/remoteproc/remoteproc_virtio.c=288=static int rproc_virtio_finalize_features(struct virtio_device vdev)\ndrivers/remoteproc/remoteproc_virtio.c-289-{\ndrivers/remoteproc/remoteproc_virtio.c:290:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-291-\tstruct fw_rsc_vdev rsc;\n--\ndrivers/remoteproc/remoteproc_virtio.c=313=static void rproc_virtio_get(struct virtio_device vdev, unsigned int offset,\n--\ndrivers/remoteproc/remoteproc_virtio.c-315-{\ndrivers/remoteproc/remoteproc_virtio.c:316:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-317-\tstruct fw_rsc_vdev rsc;\n--\ndrivers/remoteproc/remoteproc_virtio.c=331=static void rproc_virtio_set(struct virtio_device vdev, unsigned int offset,\n--\ndrivers/remoteproc/remoteproc_virtio.c-333-{\ndrivers/remoteproc/remoteproc_virtio.c:334:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-335-\tstruct fw_rsc_vdev rsc;\n--\ndrivers/remoteproc/remoteproc_virtio.c=370=static void rproc_virtio_dev_release(struct device dev)\n--\ndrivers/remoteproc/remoteproc_virtio.c-372-\tstruct virtio_device vdev = dev_to_virtio(dev);\ndrivers/remoteproc/remoteproc_virtio.c:373:\tstruct rproc_vdev rvdev = vdev_to_rvdev(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-374-\n--\ndrivers/remoteproc/remoteproc_virtio.c-383-/\ndrivers/remoteproc/remoteproc_virtio.c:384: rproc_add_virtio_dev() - register an rproc-induced virtio device\ndrivers/remoteproc/remoteproc_virtio.c-385- * @rvdev: the remote vdev\n--\ndrivers/remoteproc/remoteproc_virtio.c-392- /\ndrivers/remoteproc/remoteproc_virtio.c:393:static int rproc_add_virtio_dev(struct rproc_vdev rvdev, int id)\ndrivers/remoteproc/remoteproc_virtio.c-394-{\n--\ndrivers/remoteproc/remoteproc_virtio.c=491=static int rproc_remove_virtio_dev(struct device dev, void data)\n--\ndrivers/remoteproc/remoteproc_virtio.c-498-\ndrivers/remoteproc/remoteproc_virtio.c:499:static int rproc_vdev_do_start(struct rproc_subdev subdev)\ndrivers/remoteproc/remoteproc_virtio.c-500-{\ndrivers/remoteproc/remoteproc_virtio.c:501:\tstruct rproc_vdev rvdev = container_of(subdev, struct rproc_vdev, subdev);\ndrivers/remoteproc/remoteproc_virtio.c-502-\ndrivers/remoteproc/remoteproc_virtio.c:503:\treturn rproc_add_virtio_dev(rvdev, rvdev-\u003eid);\ndrivers/remoteproc/remoteproc_virtio.c-504-}\ndrivers/remoteproc/remoteproc_virtio.c-505-\ndrivers/remoteproc/remoteproc_virtio.c:506:static void rproc_vdev_do_stop(struct rproc_subdev subdev, bool crashed)\ndrivers/remoteproc/remoteproc_virtio.c-507-{\ndrivers/remoteproc/remoteproc_virtio.c:508:\tstruct rproc_vdev rvdev = container_of(subdev, struct rproc_vdev, subdev);\ndrivers/remoteproc/remoteproc_virtio.c-509-\tstruct device dev = \u0026rvdev-\u003epdev-\u003edev;\n--\ndrivers/remoteproc/remoteproc_virtio.c=517=static int rproc_virtio_probe(struct platform_device pdev)\n--\ndrivers/remoteproc/remoteproc_virtio.c-519-\tstruct device dev = \u0026pdev-\u003edev;\ndrivers/remoteproc/remoteproc_virtio.c:520:\tstruct rproc_vdev_data rvdev_data = dev-\u003eplatform_data;\ndrivers/remoteproc/remoteproc_virtio.c:521:\tstruct rproc_vdev rvdev;\ndrivers/remoteproc/remoteproc_virtio.c-522-\tstruct rproc rproc = container_of(dev-\u003eparent, struct rproc, dev);\n--\ndrivers/remoteproc/remoteproc_virtio.c-573-\ndrivers/remoteproc/remoteproc_virtio.c:574:\trvdev-\u003esubdev.start = rproc_vdev_do_start;\ndrivers/remoteproc/remoteproc_virtio.c:575:\trvdev-\u003esubdev.stop = rproc_vdev_do_stop;\ndrivers/remoteproc/remoteproc_virtio.c-576-\n--\ndrivers/remoteproc/remoteproc_virtio.c=598=static void rproc_virtio_remove(struct platform_device pdev)\ndrivers/remoteproc/remoteproc_virtio.c-599-{\ndrivers/remoteproc/remoteproc_virtio.c:600:\tstruct rproc_vdev rvdev = dev_get_drvdata(\u0026pdev-\u003edev);\ndrivers/remoteproc/remoteproc_virtio.c-601-\tstruct rproc *rproc = rvdev-\u003erproc;\n" }
37/2	2026/10/26 11:46	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 32842 output: 24 thoughts: 65 Thoughts: Investigating Remoteproc and Virtio_rpmsg_bus Instantiation Okay, so I'm wondering if I can instantiate `remoteproc` or `virtio_rpmsg_bus` without any actual remote processor hardware present. Logically, `remoteproc` should require remote hardware, or at least a suitable `remoteproc` driver, right? That seems like a fundamental requirement. Now the question is, what `remoteproc` drivers are actually out there? Time to take a look within the kernel source. I'll need to check the `drivers/remoteproc/` directory to get a comprehensive view of the existing options. I'm keen to understand the flexibility here.
38/2	2026/10/26 11:47	tool	codesearch-dir-index	0m Args: { "Dir": "drivers/remoteproc" } Results: { "Files": [ "amd_mbv_bram_rproc.c", "da8xx_remoteproc.c", "imx_dsp_rproc.c", "imx_rproc.c", "imx_rproc.h", "ingenic_rproc.c", "keystone_remoteproc.c", "meson_mx_ao_arc.c", "mtk_common.h", "mtk_scp.c", "mtk_scp_ipi.c", "omap_remoteproc.c", "omap_remoteproc.h", "pru_rproc.c", "pru_rproc.h", "qcom_common.c", "qcom_common.h", "qcom_pil_info.c", "qcom_pil_info.h", "qcom_q6v5.c", "qcom_q6v5.h", "qcom_q6v5_adsp.c", "qcom_q6v5_mss.c", "qcom_q6v5_pas.c", "qcom_q6v5_wcss.c", "qcom_sysmon.c", "qcom_wcnss.c", "qcom_wcnss.h", "qcom_wcnss_iris.c", "rcar_rproc.c", "remoteproc_cdev.c", "remoteproc_core.c", "remoteproc_coredump.c", "remoteproc_debugfs.c", "remoteproc_elf_helpers.h", "remoteproc_elf_loader.c", "remoteproc_internal.h", "remoteproc_sysfs.c", "remoteproc_virtio.c", "st_remoteproc.c", "st_slim_rproc.c", "stm32_rproc.c", "ti_k3_common.c", "ti_k3_common.h", "ti_k3_dsp_remoteproc.c", "ti_k3_m4_remoteproc.c", "ti_k3_r5_remoteproc.c", "ti_sci_proc.h", "wkup_m3_rproc.c", "xlnx_r5_remoteproc.c" ], "Subdirs": null }
39/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 33700 output: 32 thoughts: 708 Thoughts: My Deep Dive into `virtio_rpmsg_bus` Instantiation Okay, so I'm thinking about `virtio_rpmsg_bus` and how it gets instantiated. I need to trace this back. First, I remember that `virtio_rpmsg_bus` registers a `virtio_driver`. Let's look at the driver's ID table: that confirms it. Now, the core question is, how do these virtio devices actually come into existence in the Linux kernel? Typically, virtio devices are created in QEMU through mechanisms like `virtio-pci` or `virtio-mmio`, right? But then it hits me: QEMU doesn't have a native `virtio-rpmsg` device implemented! Could QEMU even be configured to create a virtio device with that specific device ID (7)? My understanding is that `virtio-pci` assigns specific PCI subsystem IDs corresponding to known virtio device IDs, and QEMU only supports the standard ones: net, blk, balloon, console, serial, gpu, input, crypto, 9p, vsock, rng, etc. RPMSG is missing from the list. So, where else? The answer pops up: `remoteproc`. Remoteproc is responsible for creating virtio devices, as I recall from `rproc_add_virtio_dev`, where the `id` passed is `VIRTIO_ID_RPMSG`. When does `remoteproc` create these devices? The aha moment: when the `remoteproc` driver loads firmware for a coprocessor. Think ARM Cortex-M on i.MX, TI K3, STM32, Qualcomm DSP, MediaTek SCP, you name it. The kernel's remoteproc framework creates these virtual devices for communication. Now, a new thought: can any remoteproc driver run on x86/amd64? I have to examine the list of files in `drivers/remoteproc/`: I see a huge list of architecture-specific remoteproc drivers. This reinforces my understanding that they target various heterogeneous architectures. These drivers are not directly for x86/amd64; they're designed to interface with co-processors. Finally, are there any virtual remoteproc drivers that would allow rpmsg to work on an architecture where a remote processor isn't actually present? I should check `drivers/remoteproc/Kconfig` to see the complete list of drivers and dependencies.
40/2	2026/10/26 11:47	tool	grepper	0m Args: { "Expression": "config ", "PathPrefixes": [ "drivers/remoteproc/Kconfig" ] } Results: { "Output": "drivers/remoteproc/Kconfig=2=menu \"Remoteproc drivers\"\ndrivers/remoteproc/Kconfig-3-\ndrivers/remoteproc/Kconfig:4:config REMOTEPROC\ndrivers/remoteproc/Kconfig-5-\tbool \"Support for Remote Processor subsystem\"\n--\ndrivers/remoteproc/Kconfig=15=if REMOTEPROC\ndrivers/remoteproc/Kconfig-16-\ndrivers/remoteproc/Kconfig:17:config REMOTEPROC_CDEV\ndrivers/remoteproc/Kconfig-18-\tbool \"Remoteproc character device interface\"\n--\ndrivers/remoteproc/Kconfig-25-\ndrivers/remoteproc/Kconfig:26:config AMD_MBV_BRAM_REMOTEPROC\ndrivers/remoteproc/Kconfig-27-\ttristate \"AMD MicroBlaze/V BRAM-based remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-34-\ndrivers/remoteproc/Kconfig:35:config IMX_REMOTEPROC\ndrivers/remoteproc/Kconfig-36-\ttristate \"i.MX remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-47-\ndrivers/remoteproc/Kconfig:48:config IMX_DSP_REMOTEPROC\ndrivers/remoteproc/Kconfig-49-\ttristate \"i.MX DSP remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-58-\ndrivers/remoteproc/Kconfig:59:config INGENIC_VPU_RPROC\ndrivers/remoteproc/Kconfig-60-\ttristate \"Ingenic JZ47xx VPU remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-67-\ndrivers/remoteproc/Kconfig:68:config MTK_SCP\ndrivers/remoteproc/Kconfig-69-\ttristate \"Mediatek SCP support\"\n--\ndrivers/remoteproc/Kconfig-77-\ndrivers/remoteproc/Kconfig:78:config OMAP_REMOTEPROC\ndrivers/remoteproc/Kconfig-79-\ttristate \"OMAP remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-96-\ndrivers/remoteproc/Kconfig:97:config OMAP_REMOTEPROC_WATCHDOG\ndrivers/remoteproc/Kconfig-98-\tbool \"OMAP remoteproc watchdog timer\"\n--\ndrivers/remoteproc/Kconfig-108-\ndrivers/remoteproc/Kconfig:109:config WKUP_M3_RPROC\ndrivers/remoteproc/Kconfig-110-\ttristate \"AMx3xx Wakeup M3 remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-120-\ndrivers/remoteproc/Kconfig:121:config DA8XX_REMOTEPROC\ndrivers/remoteproc/Kconfig-122-\ttristate \"DA8xx/OMAP-L13x remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-141-\ndrivers/remoteproc/Kconfig:142:config KEYSTONE_REMOTEPROC\ndrivers/remoteproc/Kconfig-143-\ttristate \"Keystone Remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-151-\ndrivers/remoteproc/Kconfig:152:config MESON_MX_AO_ARC_REMOTEPROC\ndrivers/remoteproc/Kconfig-153-\ttristate \"Amlogic Meson6/8/8b/8m2 AO ARC remote processor support\"\n--\ndrivers/remoteproc/Kconfig-162-\ndrivers/remoteproc/Kconfig:163:config PRU_REMOTEPROC\ndrivers/remoteproc/Kconfig-164-\ttristate \"TI PRU remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-174-\ndrivers/remoteproc/Kconfig:175:config QCOM_PIL_INFO\ndrivers/remoteproc/Kconfig-176-\ttristate\ndrivers/remoteproc/Kconfig-177-\ndrivers/remoteproc/Kconfig:178:config QCOM_RPROC_COMMON\ndrivers/remoteproc/Kconfig-179-\ttristate\n--\ndrivers/remoteproc/Kconfig-181-\ndrivers/remoteproc/Kconfig:182:config QCOM_Q6V5_COMMON\ndrivers/remoteproc/Kconfig-183-\ttristate\n--\ndrivers/remoteproc/Kconfig-186-\ndrivers/remoteproc/Kconfig:187:config QCOM_Q6V5_ADSP\ndrivers/remoteproc/Kconfig-188-\ttristate \"Qualcomm ADSP Peripheral Image Loader\"\n--\ndrivers/remoteproc/Kconfig-206-\ndrivers/remoteproc/Kconfig:207:config QCOM_Q6V5_MSS\ndrivers/remoteproc/Kconfig-208-\ttristate \"Qualcomm Hexagon V5 self-authenticating modem subsystem support\"\n--\ndrivers/remoteproc/Kconfig-227-\ndrivers/remoteproc/Kconfig:228:config QCOM_Q6V5_PAS\ndrivers/remoteproc/Kconfig-229-\ttristate \"Qualcomm Peripheral Authentication Service support\"\n--\ndrivers/remoteproc/Kconfig-249-\ndrivers/remoteproc/Kconfig:250:config QCOM_Q6V5_WCSS\ndrivers/remoteproc/Kconfig-251-\ttristate \"Qualcomm Hexagon based WCSS Peripheral Image Loader\"\n--\ndrivers/remoteproc/Kconfig-269-\ndrivers/remoteproc/Kconfig:270:config QCOM_SYSMON\ndrivers/remoteproc/Kconfig-271-\ttristate \"Qualcomm sysmon driver\"\n--\ndrivers/remoteproc/Kconfig-284-\ndrivers/remoteproc/Kconfig:285:config QCOM_WCNSS_PIL\ndrivers/remoteproc/Kconfig-286-\ttristate \"Qualcomm WCNSS Peripheral Image Loader\"\n--\ndrivers/remoteproc/Kconfig-302-\ndrivers/remoteproc/Kconfig:303:config RCAR_REMOTEPROC\ndrivers/remoteproc/Kconfig-304-\ttristate \"Renesas R-Car Gen3 remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-313-\ndrivers/remoteproc/Kconfig:314:config ST_REMOTEPROC\ndrivers/remoteproc/Kconfig-315-\ttristate \"ST remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-323-\ndrivers/remoteproc/Kconfig:324:config ST_SLIM_REMOTEPROC\ndrivers/remoteproc/Kconfig-325-\ttristate\ndrivers/remoteproc/Kconfig-326-\ndrivers/remoteproc/Kconfig:327:config STM32_RPROC\ndrivers/remoteproc/Kconfig-328-\ttristate \"STM32 remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-340-\ndrivers/remoteproc/Kconfig:341:config TI_K3_DSP_REMOTEPROC\ndrivers/remoteproc/Kconfig-342-\ttristate \"TI K3 DSP remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-353-\ndrivers/remoteproc/Kconfig:354:config TI_K3_M4_REMOTEPROC\ndrivers/remoteproc/Kconfig-355-\ttristate \"TI K3 M4 remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-366-\ndrivers/remoteproc/Kconfig:367:config TI_K3_R5_REMOTEPROC\ndrivers/remoteproc/Kconfig-368-\ttristate \"TI K3 R5 remoteproc support\"\n--\ndrivers/remoteproc/Kconfig-379-\ndrivers/remoteproc/Kconfig:380:config XLNX_R5_REMOTEPROC\ndrivers/remoteproc/Kconfig-381-\ttristate \"Xilinx R5 remoteproc support\"\n" }
41/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 37145 output: 34 thoughts: 60 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Remoteproc Driver Conundrum Alright, so I'm digging into these `remoteproc` drivers, and it's striking me that they're all pretty tightly coupled to the SoC architecture – ARM, MIPS, you name it. It's the expected way of things, given the nature of the beast, right? But then I hit a snag. Wait a second... what about `REMOTEPROC_CDEV`? That's got my attention. What's the point of this specific module? I'm missing something, so I had better jump into `drivers/remoteproc/remoteproc_cdev.c` and refresh my understanding of how this particular piece fits into the overall puzzle. Gotta understand what special sauce it's adding to the mix.
42/2	2026/10/26 11:47	tool	grepper	0m Args: { "Expression": "REMOTEPROC_CDEV", "PathPrefixes": [ "drivers/remoteproc/" ] } Results: { "Output": "drivers/remoteproc/Kconfig=15=if REMOTEPROC\ndrivers/remoteproc/Kconfig-16-\ndrivers/remoteproc/Kconfig:17:config REMOTEPROC_CDEV\ndrivers/remoteproc/Kconfig-18-\tbool \"Remoteproc character device interface\"\n--\ndrivers/remoteproc/Makefile=12=remoteproc-y\t\t\t\t+= remoteproc_elf_loader.o\ndrivers/remoteproc/Makefile:13:obj-$(CONFIG_REMOTEPROC_CDEV)\t\t+= remoteproc_cdev.o\ndrivers/remoteproc/Makefile-14-obj-$(CONFIG_AMD_MBV_BRAM_REMOTEPROC)\t+= amd_mbv_bram_rproc.o\n--\ndrivers/remoteproc/remoteproc_internal.h=80=void rproc_exit_sysfs(void);\ndrivers/remoteproc/remoteproc_internal.h-81-\ndrivers/remoteproc/remoteproc_internal.h:82:#ifdef CONFIG_REMOTEPROC_CDEV\ndrivers/remoteproc/remoteproc_internal.h-83-void rproc_init_cdev(void);\n" }
43/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 37741 output: 42 thoughts: 18 Thoughts: Okay, let's dive into `remoteproc_cdev.c`. I need to understand this module's role. My initial hunch is that it likely deals with creating character device nodes related to remote processors – probably for control, data transfer, or status monitoring. I'm guessing it bridges the gap between the kernel's device model and the remoteproc framework, facilitating communication with those remote processors. I'll be looking for how it handles device registration and unregistration, how it interacts with the remoteproc driver core, what structures it uses to represent remote processors in the device tree, and importantly, the methods exposed to userspace – the read/write operations, ioctls, or anything else that allows user applications to interact with the remote processor. Understanding the flow of data and control is key. I'll need to see how the character devices are named and where they reside. What are the security implications? Finally, I need to know the error-handling strategies employed in case of communication failure or unexpected conditions during data transfer. Let's dig in and see if my assumptions hold true.
44/2	2026/10/26 11:47	tool	read-file	0m Args: { "File": "drivers/remoteproc/remoteproc_cdev.c", "FirstLine": 1, "LineCount": 50 } Results: { "Contents": " 1:\t// SPDX-License-Identifier: GPL-2.0-only\n 2:\t/\n 3:\t Character device interface driver for Remoteproc framework.\n 4:\t \n 5:\t Copyright (c) 2020, The Linux Foundation. All rights reserved.\n 6:\t /\n 7:\t\n 8:\t#include \u003clinux/cdev.h\u003e\n 9:\t#include \u003clinux/compat.h\u003e\n 10:\t#include \u003clinux/fs.h\u003e\n 11:\t#include \u003clinux/module.h\u003e\n 12:\t#include \u003clinux/remoteproc.h\u003e\n 13:\t#include \u003clinux/uaccess.h\u003e\n 14:\t#include \u003cuapi/linux/remoteproc_cdev.h\u003e\n 15:\t\n 16:\t#include \"remoteproc_internal.h\"\n 17:\t\n 18:\t#define NUM_RPROC_DEVICES\t64\n 19:\tstatic dev_t rproc_major;\n 20:\t\n 21:\tstatic ssize_t rproc_cdev_write(struct file filp, const char __user buf, size_t len, loff_t pos)\n 22:\t{\n 23:\t\tstruct rproc rproc = container_of(filp-\u003ef_inode-\u003ei_cdev, struct rproc, cdev);\n 24:\t\tint ret = 0;\n 25:\t\tchar cmd[10];\n 26:\t\n 27:\t\tif (!len \|\| len \u003e sizeof(cmd))\n 28:\t\t\treturn -EINVAL;\n 29:\t\n 30:\t\tret = copy_from_user(cmd, buf, len);\n 31:\t\tif (ret)\n 32:\t\t\treturn -EFAULT;\n 33:\t\n 34:\t\tif (!strncmp(cmd, \"start\", len)) {\n 35:\t\t\tret = rproc_boot(rproc);\n 36:\t\t} else if (!strncmp(cmd, \"stop\", len)) {\n 37:\t\t\tret = rproc_shutdown(rproc);\n 38:\t\t} else if (!strncmp(cmd, \"detach\", len)) {\n 39:\t\t\tret = rproc_detach(rproc);\n 40:\t\t} else {\n 41:\t\t\tdev_err(\u0026rproc-\u003edev, \"Unrecognized option\\n\");\n 42:\t\t\tret = -EINVAL;\n 43:\t\t}\n 44:\t\n 45:\t\treturn ret ? ret : len;\n 46:\t}\n 47:\t\n 48:\tstatic long rproc_device_ioctl(struct file filp, unsigned int ioctl, unsigned long arg)\n 49:\t{\n 50:\t\tstruct rproc *rproc = container_of(filp-\u003ef_inode-\u003ei_cdev, struct rproc, cdev);\n" }
45/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 38774 output: 41 thoughts: 57 Thoughts: Investigating RPMSG Accessibility in Syzkaller Okay, so the question is, can we actually reach `rpmsg` functionalities through Syzkaller? My first instinct is to immediately jump into a search. Before I even think about a complicated analysis, let's see if anyone has already blazed this trail. I need to check if Syzkaller itself, or anyone else using it, has filed any bug reports specifically targeting `rpmsg_char` or simply `rpmsg`. That's the obvious first step, right? Following that, I need to get my hands dirty with the kernel's Git log. A grep for `rpmsg_char` and `syzbot` would likely be a good starting point. This should show me any development activity or bug reports associated with the intersection of `rpmsg` and Syzkaller's automated testing. I am expecting that this search will yield meaningful results.
46/2	2026/10/26 11:47	tool	grepper	0m Error: no matches Args: { "Expression": "syzbot.rpmsg\|Reported-by: syzbot", "PathPrefixes": [ "drivers/rpmsg/" ] } Results:* { "error": "no matches" }
47/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 39079 output: 22 thoughts: 173 Thoughts: Analyzing the RPMSG Flow Control Patch Okay, first things first, before I dive too deep, let's back up a bit. My instinct is to understand the why behind this change. I need context. My first thought is to search the commit history for `drivers/rpmsg/rpmsg_char.c` or recent commits related to this area. I want to see the rationale behind this patch. Ideally, I'd use `git log`, but I don't have that tool available, so I'll need to work around it. I can probably glean the information from the commit message itself or by grepping through comments. Aha! Let's see... I need to identify the exact patch commit within this workspace. Alright, it's `commit ef9f789b3f5fe7743026f0349064fb807a2de3c9`. Now to analyze the commit message. "syz-cluster: applied patch under review". Okay, that gives me a small clue, but not enough context, so my next step is to examine `rpmsg_set_flow_control` function within the `drivers/rpmsg/` directory. I'll need to figure out which commit introduced flow control, or what this specific commit is fixing to fully grasp its purpose.
48/2	2026/10/26 11:47	tool	grepper	0m Args: { "Expression": "rpmsg_set_flow_control" } Results: { "Output": "drivers/rpmsg/rpmsg_char.c=327=static long rpmsg_eptdev_ioctl(struct file fp, unsigned int cmd,\n--\ndrivers/rpmsg/rpmsg_char.c-349-\t\tif (eptdev-\u003eept)\ndrivers/rpmsg/rpmsg_char.c:350:\t\t\tret = rpmsg_set_flow_control(eptdev-\u003eept, set,\ndrivers/rpmsg/rpmsg_char.c-351-\t\t\t\t\t\t eptdev-\u003echinfo.dst);\n--\ndrivers/rpmsg/rpmsg_core.c=270=EXPORT_SYMBOL(rpmsg_poll);\n--\ndrivers/rpmsg/rpmsg_core.c-272-/\ndrivers/rpmsg/rpmsg_core.c:273: rpmsg_set_flow_control() - request remote to pause/resume transmission\ndrivers/rpmsg/rpmsg_core.c-274- * @ept:\tthe rpmsg endpoint\n--\ndrivers/rpmsg/rpmsg_core.c-279- /\ndrivers/rpmsg/rpmsg_core.c:280:int rpmsg_set_flow_control(struct rpmsg_endpoint ept, bool pause, u32 dst)\ndrivers/rpmsg/rpmsg_core.c-281-{\n--\ndrivers/rpmsg/rpmsg_core.c-288-}\ndrivers/rpmsg/rpmsg_core.c:289:EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);\ndrivers/rpmsg/rpmsg_core.c-290-\n--\ndrivers/rpmsg/rpmsg_internal.h=35=struct rpmsg_device_ops {\n--\ndrivers/rpmsg/rpmsg_internal.h-55- * @poll:\t\tsee @rpmsg_poll(), optional\ndrivers/rpmsg/rpmsg_internal.h:56: * @set_flow_control:\tsee @rpmsg_set_flow_control(), optional\ndrivers/rpmsg/rpmsg_internal.h-57- * @get_mtu:\t\tsee @rpmsg_get_mtu(), optional\n--\ninclude/linux/rpmsg.h=190=ssize_t rpmsg_get_mtu(struct rpmsg_endpoint ept);\ninclude/linux/rpmsg.h-191-\ninclude/linux/rpmsg.h:192:int rpmsg_set_flow_control(struct rpmsg_endpoint ept, bool pause, u32 dst);\ninclude/linux/rpmsg.h-193-\n--\ninclude/linux/rpmsg.h=293=static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint ept)\n--\ninclude/linux/rpmsg.h-300-\ninclude/linux/rpmsg.h:301:static inline int rpmsg_set_flow_control(struct rpmsg_endpoint ept, bool pause, u32 dst)\ninclude/linux/rpmsg.h-302-{\n" }
49/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 40302 output: 39 thoughts: 32 Thoughts: Okay, let's dive into this. Here's my thought process on this: Investigating the rpmsg Flow Control Implementation Hold on a second! Before I proceed any further, I need to verify something fundamental. I should double-check the implementation of `rpmsg_set_flow_control`, specifically in the `drivers/rpmsg/rpmsg_core.c` file. This is crucial. Flow control is a critical element in any reliable communication system, and I can't proceed without a solid understanding of how it's handled at this low level. I need to refresh my memory on the specifics of this implementation. What are the mutexes? The conditions? The data structures? Any quirks or nuances in the way it's designed? I need to build a mental picture of it and cross reference it with my higher level design to verify it makes sense. I have to make sure it functions as expected to determine what the next best steps are. Let me open that file and refresh my memory...
50/2	2026/10/26 11:47	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_core.c", "FirstLine": 270, "LineCount": 30 } Results: { "Contents": " 270:\tEXPORT_SYMBOL(rpmsg_poll);\n 271:\t\n 272:\t/*\n 273:\t rpmsg_set_flow_control() - request remote to pause/resume transmission\n 274:\t * @ept:\tthe rpmsg endpoint\n 275:\t * @pause:\tpause transmission\n 276:\t * @dst:\tdestination address of the endpoint\n 277:\t \n 278:\t Return: 0 on success and an appropriate error value on failure.\n 279:\t /\n 280:\tint rpmsg_set_flow_control(struct rpmsg_endpoint ept, bool pause, u32 dst)\n 281:\t{\n 282:\t\tif (WARN_ON(!ept))\n 283:\t\t\treturn -EINVAL;\n 284:\t\tif (!ept-\u003eops-\u003eset_flow_control)\n 285:\t\t\treturn -EOPNOTSUPP;\n 286:\t\n 287:\t\treturn ept-\u003eops-\u003eset_flow_control(ept, pause, dst);\n 288:\t}\n 289:\tEXPORT_SYMBOL_GPL(rpmsg_set_flow_control);\n 290:\t\n 291:\t/*\n 292:\t rpmsg_get_mtu() - get maximum transmission buffer size for sending message.\n 293:\t * @ept: the rpmsg endpoint\n 294:\t \n 295:\t This function returns maximum buffer size available for a single outgoing message.\n 296:\t \n 297:\t Return: the maximum transmission size on success and an appropriate error\n 298:\t * value on failure.\n 299:\t */\n" }
51/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 41039 output: 22 thoughts: 1153 Thoughts: Analyzing the Reachability of `rpmsg_char.c` Vulnerability Okay, so I've been digging into this patch related to `rpmsg_set_flow_control` and the potential for a null pointer dereference or `WARN_ON` trigger within `rpmsg_char.c`. The patch seems sound in that it adds the necessary locking and null pointer check around calls to `rpmsg_set_flow_control` from `rpmsg_char.c`. This protects against a race condition where the `eptdev->ept` pointer could be NULL, particularly after the endpoint device is destroyed or before it is fully initialized, which would have resulted in that warning or potential crash. My primary concern now is whether this code is even reachable in a standard virtualized environment like QEMU on amd64, since this is critical to whether it's worth fuzzing or not. I'm following the triage philosophy here: reachability is the primary gate. First, I examined `rpmsg_set_flow_control`. The core issue is that `rpmsg_set_flow_control()` can be called with `ept` set to NULL. My goal is to determine if this can be triggered under normal conditions in a virtualized AMD64 environment. I looked at the code and determined that the vulnerability is in `rpmsg_char.c`, in the path that calls `rpmsg_set_flow_control` from an ioctl call. I need to understand how devices get created, used and destroyed. I identified the key functions for device creation: `rpmsg_chrdev_probe` and `rpmsg_chrdev_eptdev_create`. `rpmsg_chrdev_probe` is called when an `rpmsg_device` binds to `rpmsg_chrdev_driver`, while `rpmsg_chrdev_eptdev_create` is called within the `rpmsg_ctrl.c` path to handle the `RPMSG_CREATE_EPT_IOCTL`. Now I need to understand the path for those. `rpmsg_device` instances are created with `rpmsg_register_device()` or `rpmsg_register_device_override()`. `rpmsg_ctrldev_register_device(rpdev)` is the function to create the control device. From there, I see it's called by: - `drivers/rpmsg/qcom_glink_native.c` (Qualcomm GLINK) - `drivers/rpmsg/qcom_smd.c` (Qualcomm SMD) - `drivers/rpmsg/virtio_rpmsg_bus.c` So the question is: Are these drivers reachable in a standard QEMU environment on amd64? This is the crucial question, whether these drivers, or components that will create the endpoints, are supported. I will have to investigate what the dependencies are, and whether any of these drivers are supported in QEMU on an amd64 machine. I need to grep the code tree for a broader view.
52/2	2026/10/26 11:47	tool	codesearch-dir-index	0m Args: { "Dir": "drivers/rpmsg" } Results: { "Files": [ "mtk_rpmsg.c", "qcom_glink_native.c", "qcom_glink_native.h", "qcom_glink_rpm.c", "qcom_glink_smem.c", "qcom_glink_ssr.c", "qcom_glink_trace.h", "qcom_smd.c", "rpmsg_char.c", "rpmsg_char.h", "rpmsg_core.c", "rpmsg_ctrl.c", "rpmsg_internal.h", "rpmsg_ns.c", "virtio_rpmsg_bus.c" ], "Subdirs": null }
53/2	2026/10/26 11:47	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 43040 output: 32 thoughts: 144 Thoughts: RPMSG Driver Landscape: Initial Assessment and Broader Search Okay, so I'm diving into the RPMSG driver ecosystem. My initial focus is to understand which drivers are registering RPMSG devices or binding to the `rpmsg_bus`. I know a few off the top of my head, like the MediaTek SCP driver (`mtk_rpmsg.c`), the Qualcomm Glink variants (`qcom_glink_.c`), and the Qualcomm SMD driver (`qcom_smd.c`), all neatly tucked away in `drivers/rpmsg`. Oh, and of course, the Virtio RPMSG bus (`virtio_rpmsg_bus.c`). But hold on a second... are these all* the RPMSG drivers? That seems a little too convenient. I need to be more thorough here. Time to expand the search. I need to cast a wider net and check all references to `rpmsg_register_device` and crucially, any binding to or interaction with the `rpmsg_bus` across the entire kernel source. I can't afford to miss anything. Gotta make sure I have the full picture.
54/2	2026/10/26 11:48	tool	grepper	0m Args: { "Expression": "rpmsg_register_device\|rpmsg_bus_type\|rpmsg_bus" } Results: { "Output": "drivers/rpmsg/Makefile=12=obj-$(CONFIG_RPMSG_QCOM_SMD)\t+= qcom_smd.o\ndrivers/rpmsg/Makefile:13:obj-$(CONFIG_RPMSG_VIRTIO)\t+= virtio_rpmsg_bus.o\n--\ndrivers/rpmsg/mtk_rpmsg.c=179=mtk_rpmsg_match_device_subnode(struct device_node node, const char channel)\n--\ndrivers/rpmsg/mtk_rpmsg.c-196-\ndrivers/rpmsg/mtk_rpmsg.c:197:static int mtk_rpmsg_register_device(struct mtk_rpmsg_rproc_subdev mtk_subdev,\ndrivers/rpmsg/mtk_rpmsg.c-198-\t\t\t\t struct rpmsg_channel_info info)\n--\ndrivers/rpmsg/mtk_rpmsg.c-220-\ndrivers/rpmsg/mtk_rpmsg.c:221:\treturn rpmsg_register_device(rpdev);\ndrivers/rpmsg/mtk_rpmsg.c-222-}\n--\ndrivers/rpmsg/mtk_rpmsg.c=224=static void mtk_register_device_work_function(struct work_struct register_work)\n--\ndrivers/rpmsg/mtk_rpmsg.c-237-\t\tmutex_unlock(\u0026subdev-\u003echannels_lock);\ndrivers/rpmsg/mtk_rpmsg.c:238:\t\tret = mtk_rpmsg_register_device(subdev, \u0026info-\u003einfo);\ndrivers/rpmsg/mtk_rpmsg.c-239-\t\tmutex_lock(\u0026subdev-\u003echannels_lock);\n--\ndrivers/rpmsg/qcom_glink_native.c=1629=static int qcom_glink_rx_open(struct qcom_glink glink, unsigned int rcid,\n--\ndrivers/rpmsg/qcom_glink_native.c-1687-\ndrivers/rpmsg/qcom_glink_native.c:1688:\t\tret = rpmsg_register_device(rpdev);\ndrivers/rpmsg/qcom_glink_native.c-1689-\t\tif (ret)\n--\ndrivers/rpmsg/qcom_smd.c=1074=static int qcom_smd_create_device(struct qcom_smd_channel channel)\n--\ndrivers/rpmsg/qcom_smd.c-1101-\ndrivers/rpmsg/qcom_smd.c:1102:\treturn rpmsg_register_device(rpdev);\ndrivers/rpmsg/qcom_smd.c-1103-}\n--\ndrivers/rpmsg/rpmsg_core.c=493=static void rpmsg_dev_remove(struct device dev)\n--\ndrivers/rpmsg/rpmsg_core.c-507-\ndrivers/rpmsg/rpmsg_core.c:508:static const struct bus_type rpmsg_bus = {\ndrivers/rpmsg/rpmsg_core.c-509-\t.name\t\t= \"rpmsg\",\n--\ndrivers/rpmsg/rpmsg_core.c-519- * A helper for registering rpmsg device with driver override and name.\ndrivers/rpmsg/rpmsg_core.c:520: * Drivers should not be using it, but instead rpmsg_register_device().\ndrivers/rpmsg/rpmsg_core.c-521- /\ndrivers/rpmsg/rpmsg_core.c:522:int rpmsg_register_device_override(struct rpmsg_device rpdev,\ndrivers/rpmsg/rpmsg_core.c-523-\t\t\t\t const char driver_override)\n--\ndrivers/rpmsg/rpmsg_core.c-533-\ndrivers/rpmsg/rpmsg_core.c:534:\tdev-\u003ebus = \u0026rpmsg_bus;\ndrivers/rpmsg/rpmsg_core.c-535-\n--\ndrivers/rpmsg/rpmsg_core.c-553-}\ndrivers/rpmsg/rpmsg_core.c:554:EXPORT_SYMBOL(rpmsg_register_device_override);\ndrivers/rpmsg/rpmsg_core.c-555-\ndrivers/rpmsg/rpmsg_core.c:556:int rpmsg_register_device(struct rpmsg_device rpdev)\ndrivers/rpmsg/rpmsg_core.c-557-{\ndrivers/rpmsg/rpmsg_core.c:558:\treturn rpmsg_register_device_override(rpdev, NULL);\ndrivers/rpmsg/rpmsg_core.c-559-}\ndrivers/rpmsg/rpmsg_core.c:560:EXPORT_SYMBOL(rpmsg_register_device);\ndrivers/rpmsg/rpmsg_core.c-561-\n--\ndrivers/rpmsg/rpmsg_core.c=590=int __register_rpmsg_driver(struct rpmsg_driver rpdrv, struct module owner)\ndrivers/rpmsg/rpmsg_core.c-591-{\ndrivers/rpmsg/rpmsg_core.c:592:\trpdrv-\u003edrv.bus = \u0026rpmsg_bus;\ndrivers/rpmsg/rpmsg_core.c-593-\trpdrv-\u003edrv.owner = owner;\n--\ndrivers/rpmsg/rpmsg_core.c=609=static int __init rpmsg_init(void)\n--\ndrivers/rpmsg/rpmsg_core.c-618-\ndrivers/rpmsg/rpmsg_core.c:619:\tret = bus_register(\u0026rpmsg_bus);\ndrivers/rpmsg/rpmsg_core.c-620-\tif (ret) {\n--\ndrivers/rpmsg/rpmsg_core.c=628=static void __exit rpmsg_fini(void)\ndrivers/rpmsg/rpmsg_core.c-629-{\ndrivers/rpmsg/rpmsg_core.c:630:\tbus_unregister(\u0026rpmsg_bus);\ndrivers/rpmsg/rpmsg_core.c-631-\tclass_unregister(\u0026rpmsg_class);\n--\ndrivers/rpmsg/rpmsg_internal.h=82=int rpmsg_release_channel(struct rpmsg_device rpdev,\n--\ndrivers/rpmsg/rpmsg_internal.h-87- \ndrivers/rpmsg/rpmsg_internal.h:88: * This function wraps rpmsg_register_device() preparing the rpdev for use as\ndrivers/rpmsg/rpmsg_internal.h-89- * basis for the rpmsg chrdev.\n--\ndrivers/rpmsg/rpmsg_internal.h=91=static inline int rpmsg_ctrldev_register_device(struct rpmsg_device rpdev)\ndrivers/rpmsg/rpmsg_internal.h-92-{\ndrivers/rpmsg/rpmsg_internal.h:93:\treturn rpmsg_register_device_override(rpdev, \"rpmsg_ctrl\");\ndrivers/rpmsg/rpmsg_internal.h-94-}\n--\ndrivers/rpmsg/rpmsg_ns.c-17- \ndrivers/rpmsg/rpmsg_ns.c:18: * This function wraps rpmsg_register_device() preparing the rpdev for use as\ndrivers/rpmsg/rpmsg_ns.c-19- * basis for the rpmsg name service device.\n--\ndrivers/rpmsg/rpmsg_ns.c=21=int rpmsg_ns_register_device(struct rpmsg_device rpdev)\n--\ndrivers/rpmsg/rpmsg_ns.c-25-\ndrivers/rpmsg/rpmsg_ns.c:26:\treturn rpmsg_register_device_override(rpdev, \"rpmsg_ns\");\ndrivers/rpmsg/rpmsg_ns.c-27-}\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c=385=static struct rpmsg_device __rpmsg_create_channel(struct virtproc_info vrp,\n--\ndrivers/rpmsg/virtio_rpmsg_bus.c-426-\trpdev-\u003edev.release = virtio_rpmsg_release_device;\ndrivers/rpmsg/virtio_rpmsg_bus.c:427:\tret = rpmsg_register_device(rpdev);\ndrivers/rpmsg/virtio_rpmsg_bus.c-428-\tif (ret)\n--\ninclude/linux/rpmsg.h=159=static inline __rpmsg64 cpu_to_rpmsg64(struct rpmsg_device rpdev, u64 val)\n--\ninclude/linux/rpmsg.h-168-\ninclude/linux/rpmsg.h:169:int rpmsg_register_device_override(struct rpmsg_device rpdev,\ninclude/linux/rpmsg.h-170-\t\t\t\t const char driver_override);\ninclude/linux/rpmsg.h:171:int rpmsg_register_device(struct rpmsg_device rpdev);\ninclude/linux/rpmsg.h-172-int rpmsg_unregister_device(struct device parent,\n--\ninclude/linux/rpmsg.h=192=int rpmsg_set_flow_control(struct rpmsg_endpoint ept, bool pause, u32 dst);\n--\ninclude/linux/rpmsg.h-195-\ninclude/linux/rpmsg.h:196:static inline int rpmsg_register_device_override(struct rpmsg_device rpdev,\ninclude/linux/rpmsg.h-197-\t\t\t\t\t\t const char driver_override)\n--\ninclude/linux/rpmsg.h-201-\ninclude/linux/rpmsg.h:202:static inline int rpmsg_register_device(struct rpmsg_device rpdev)\ninclude/linux/rpmsg.h-203-{\n" }
55/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 45895 output: 32 thoughts: 650 Thoughts: Investigating RPMSG Device Registration and Virtio Implementation Okay, let's break this down. My initial focus is on `rpmsg_register_device`. I see it's only called in a few specific places: `mtk_rpmsg.c` (requiring MTK SCP), `qcom_glink_native.c`, and `qcom_smd.c` (both Qualcomm-specific), and finally, `virtio_rpmsg_bus.c`. The last one is the most interesting because it leverages the `virtio_ipc_driver`. So, the `virtio_ipc_driver` has an ID table with `VIRTIO_ID_RPMSG` (ID 7). The question then becomes: can a `VIRTIO_ID_RPMSG` device ever actually be probed in an environment like QEMU or Google Compute Engine? That's the crux of this. Now, can virtio devices be instantiated via `virtio_pci`? I need to know if QEMU itself provides a virtio device with ID 7 (RPMSG). Time to check QEMU's supported virtio IDs. Looking at what QEMU offers, it's clear that it has implementations for network, block, console, RNG, and balloon devices, but no dedicated `virtio-rpmsg` device! That's a major roadblock. QEMU does not implement `VIRTIO_ID_RPMSG`. Okay, what about other virtio methods? Could it be possible to instantiate the device by using `virtio-mmio` or `virtio-pci` with a custom device ID? Still no dice. QEMU simply doesn't have it. Vhost? No, `vhost-user` isn't relevant to rpmsg either. What about mock/virtual devices? Is there any virtio-rpmsg or rpmsg device in the kernel or syzkaller? I haven't seen any. Okay, let's explore this from a different angle: can user-space create virtio devices directly? Can it? No, `vhost` is host-side. But what about `/dev/vhost-vdpa` or other vdpa methods? Can vDPA create a virtio device with ID 7? I need to check `vdpa_sim` (vDPA simulator) or other vdpa drivers.
56/2	2026/10/26 11:48	tool	grepper	0m Args: { "Expression": "VIRTIO_ID_", "PathPrefixes": [ "drivers/vdpa/" ] } Results: { "Output": "drivers/vdpa/alibaba/eni_vdpa.c=544=static struct pci_device_id eni_pci_ids[] = {\n--\ndrivers/vdpa/alibaba/eni_vdpa.c-547-\t\t\t PCI_SUBVENDOR_ID_REDHAT_QUMRANET,\ndrivers/vdpa/alibaba/eni_vdpa.c:548:\t\t\t VIRTIO_ID_NET) },\ndrivers/vdpa/alibaba/eni_vdpa.c-549-\t{ 0 },\n--\ndrivers/vdpa/ifcvf/ifcvf_base.c=261=u32 ifcvf_get_config_size(struct ifcvf_hw hw)\n--\ndrivers/vdpa/ifcvf/ifcvf_base.c-273-\tswitch (hw-\u003edev_type) {\ndrivers/vdpa/ifcvf/ifcvf_base.c:274:\tcase VIRTIO_ID_NET:\ndrivers/vdpa/ifcvf/ifcvf_base.c-275-\t\tconfig_size = min(cap_size, net_config_size);\ndrivers/vdpa/ifcvf/ifcvf_base.c-276-\t\tbreak;\ndrivers/vdpa/ifcvf/ifcvf_base.c:277:\tcase VIRTIO_ID_BLOCK:\ndrivers/vdpa/ifcvf/ifcvf_base.c-278-\t\tconfig_size = min(cap_size, blk_config_size);\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c=364=static u64 ifcvf_vdpa_get_device_features(struct vdpa_device vdpa_dev)\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c-371-\ndrivers/vdpa/ifcvf/ifcvf_main.c:372:\tif (type == VIRTIO_ID_NET \|\| type == VIRTIO_ID_BLOCK)\ndrivers/vdpa/ifcvf/ifcvf_main.c-373-\t\tfeatures = ifcvf_get_dev_features(vf);\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c=663=static struct virtio_device_id id_table_net[] = {\ndrivers/vdpa/ifcvf/ifcvf_main.c:664:\t{VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID},\ndrivers/vdpa/ifcvf/ifcvf_main.c-665-\t{0},\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c=668=static struct virtio_device_id id_table_blk[] = {\ndrivers/vdpa/ifcvf/ifcvf_main.c:669:\t{VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID},\ndrivers/vdpa/ifcvf/ifcvf_main.c-670-\t{0},\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c=770=static int ifcvf_probe(struct pci_dev pdev, const struct pci_device_id id)\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c-828-\tswitch (dev_type) {\ndrivers/vdpa/ifcvf/ifcvf_main.c:829:\tcase VIRTIO_ID_NET:\ndrivers/vdpa/ifcvf/ifcvf_main.c-830-\t\tifcvf_mgmt_dev-\u003emdev.id_table = id_table_net;\ndrivers/vdpa/ifcvf/ifcvf_main.c-831-\t\tbreak;\ndrivers/vdpa/ifcvf/ifcvf_main.c:832:\tcase VIRTIO_ID_BLOCK:\ndrivers/vdpa/ifcvf/ifcvf_main.c-833-\t\tifcvf_mgmt_dev-\u003emdev.id_table = id_table_blk;\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c=874=static struct pci_device_id ifcvf_pci_ids[] = {\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c-885-\t\t\t PCI_VENDOR_ID_INTEL,\ndrivers/vdpa/ifcvf/ifcvf_main.c:886:\t\t\t VIRTIO_ID_NET) },\ndrivers/vdpa/ifcvf/ifcvf_main.c-887-\t/* C5000X-PL block device /\n--\ndrivers/vdpa/ifcvf/ifcvf_main.c-890-\t\t\t PCI_VENDOR_ID_INTEL,\ndrivers/vdpa/ifcvf/ifcvf_main.c:891:\t\t\t VIRTIO_ID_BLOCK) },\ndrivers/vdpa/ifcvf/ifcvf_main.c-892-\n--\ndrivers/vdpa/mlx5/net/mlx5_vnet.c=2966=static u32 mlx5_vdpa_get_device_id(struct vdpa_device vdev)\ndrivers/vdpa/mlx5/net/mlx5_vnet.c-2967-{\ndrivers/vdpa/mlx5/net/mlx5_vnet.c:2968:\treturn VIRTIO_ID_NET;\ndrivers/vdpa/mlx5/net/mlx5_vnet.c-2969-}\n--\ndrivers/vdpa/mlx5/net/mlx5_vnet.c=4099=static struct virtio_device_id id_table[] = {\ndrivers/vdpa/mlx5/net/mlx5_vnet.c:4100:\t{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },\ndrivers/vdpa/mlx5/net/mlx5_vnet.c-4101-\t{ 0 },\n--\ndrivers/vdpa/octeon_ep/octep_vdpa_hw.c=360=static u32 octep_get_config_size(struct octep_hw oct_hw)\n--\ndrivers/vdpa/octeon_ep/octep_vdpa_hw.c-362-\tswitch (oct_hw-\u003edev_id) {\ndrivers/vdpa/octeon_ep/octep_vdpa_hw.c:363:\tcase VIRTIO_ID_NET:\ndrivers/vdpa/octeon_ep/octep_vdpa_hw.c-364-\t\treturn sizeof(struct virtio_net_config);\ndrivers/vdpa/octeon_ep/octep_vdpa_hw.c:365:\tcase VIRTIO_ID_CRYPTO:\ndrivers/vdpa/octeon_ep/octep_vdpa_hw.c-366-\t\treturn sizeof(struct virtio_crypto_config);\n--\ndrivers/vdpa/octeon_ep/octep_vdpa_main.c=643=static struct virtio_device_id id_table[] = {\ndrivers/vdpa/octeon_ep/octep_vdpa_main.c:644:\t{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },\ndrivers/vdpa/octeon_ep/octep_vdpa_main.c-645-\t{ 0 },\n--\ndrivers/vdpa/pds/vdpa_dev.c=363=static u32 pds_vdpa_get_device_id(struct vdpa_device vdpa_dev)\ndrivers/vdpa/pds/vdpa_dev.c-364-{\ndrivers/vdpa/pds/vdpa_dev.c:365:\treturn VIRTIO_ID_NET;\ndrivers/vdpa/pds/vdpa_dev.c-366-}\n--\ndrivers/vdpa/pds/vdpa_dev.c=606=static struct virtio_device_id pds_vdpa_id_table[] = {\ndrivers/vdpa/pds/vdpa_dev.c:607:\t{VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID},\ndrivers/vdpa/pds/vdpa_dev.c-608-\t{0},\n--\ndrivers/vdpa/vdpa.c=559=static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff skb, struct genl_info info)\n--\ndrivers/vdpa/vdpa.c-645-\tif (config.mask \u0026 VDPA_DEV_NET_ATTRS_MASK \u0026\u0026\ndrivers/vdpa/vdpa.c:646:\t !(classes \u0026 BIT_ULL(VIRTIO_ID_NET))) {\ndrivers/vdpa/vdpa.c-647-\t\tNL_SET_ERR_MSG_MOD(info-\u003eextack,\n--\ndrivers/vdpa/vdpa.c-653-\t config.mask \u0026 BIT_ULL(VDPA_ATTR_DEV_FEATURES) \u0026\u0026\ndrivers/vdpa/vdpa.c:654:\t classes \u0026 BIT_ULL(VIRTIO_ID_NET) \u0026\u0026 ncls \u003e 1 \u0026\u0026\ndrivers/vdpa/vdpa.c-655-\t config.device_features \u0026 VIRTIO_DEVICE_F_MASK) {\n--\ndrivers/vdpa/vdpa.c=1121=vdpa_dev_config_fill(struct vdpa_device vdev, struct sk_buff msg, u32 portid, u32 seq,\n--\ndrivers/vdpa/vdpa.c-1160-\tswitch (device_id) {\ndrivers/vdpa/vdpa.c:1161:\tcase VIRTIO_ID_NET:\ndrivers/vdpa/vdpa.c-1162-\t\terr = vdpa_dev_net_config_fill(vdev, msg);\ndrivers/vdpa/vdpa.c-1163-\t\tbreak;\ndrivers/vdpa/vdpa.c:1164:\tcase VIRTIO_ID_BLOCK:\ndrivers/vdpa/vdpa.c-1165-\t\terr = vdpa_dev_blk_config_fill(vdev, msg);\n--\ndrivers/vdpa/vdpa.c=1236=static int vdpa_dev_vendor_stats_fill(struct vdpa_device vdev,\n--\ndrivers/vdpa/vdpa.c-1263-\tswitch (device_id) {\ndrivers/vdpa/vdpa.c:1264:\tcase VIRTIO_ID_NET:\ndrivers/vdpa/vdpa.c-1265-\t\tif (index \u003e VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX) {\n--\ndrivers/vdpa/vdpa.c=1360=static int vdpa_nl_cmd_dev_attr_set_doit(struct sk_buff skb,\n--\ndrivers/vdpa/vdpa.c-1387-\tclasses = vdpa_mgmtdev_get_classes(vdev-\u003emdev, NULL);\ndrivers/vdpa/vdpa.c:1388:\tif (classes \u0026 BIT_ULL(VIRTIO_ID_NET)) {\ndrivers/vdpa/vdpa.c-1389-\t\terr = vdpa_dev_net_device_attr_set(vdev, info);\n--\ndrivers/vdpa/vdpa_sim/vdpa_sim_blk.c=410=static int vdpasim_blk_dev_add(struct vdpa_mgmt_dev mdev, const char name,\n--\ndrivers/vdpa/vdpa_sim/vdpa_sim_blk.c-419-\tdev_attr.name = name;\ndrivers/vdpa/vdpa_sim/vdpa_sim_blk.c:420:\tdev_attr.id = VIRTIO_ID_BLOCK;\ndrivers/vdpa/vdpa_sim/vdpa_sim_blk.c-421-\tdev_attr.supported_features = VDPASIM_BLK_FEATURES;\n--\ndrivers/vdpa/vdpa_sim/vdpa_sim_blk.c=473=static struct virtio_device_id id_table[] = {\ndrivers/vdpa/vdpa_sim/vdpa_sim_blk.c:474:\t{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },\ndrivers/vdpa/vdpa_sim/vdpa_sim_blk.c-475-\t{ 0 },\n--\ndrivers/vdpa/vdpa_sim/vdpa_sim_net.c=470=static int vdpasim_net_dev_add(struct vdpa_mgmt_dev mdev, const char name,\n--\ndrivers/vdpa/vdpa_sim/vdpa_sim_net.c-479-\tdev_attr.name = name;\ndrivers/vdpa/vdpa_sim/vdpa_sim_net.c:480:\tdev_attr.id = VIRTIO_ID_NET;\ndrivers/vdpa/vdpa_sim/vdpa_sim_net.c-481-\tdev_attr.supported_features = VDPASIM_NET_FEATURES;\n--\ndrivers/vdpa/vdpa_sim/vdpa_sim_net.c=540=static struct virtio_device_id id_table[] = {\ndrivers/vdpa/vdpa_sim/vdpa_sim_net.c:541:\t{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },\ndrivers/vdpa/vdpa_sim/vdpa_sim_net.c-542-\t{ 0 },\n--\ndrivers/vdpa/vdpa_user/vduse_dev.c=181=static u32 allowed_device_id[] = {\ndrivers/vdpa/vdpa_user/vduse_dev.c:182:\tVIRTIO_ID_BLOCK,\ndrivers/vdpa/vdpa_user/vduse_dev.c:183:\tVIRTIO_ID_NET,\ndrivers/vdpa/vdpa_user/vduse_dev.c:184:\tVIRTIO_ID_FS,\ndrivers/vdpa/vdpa_user/vduse_dev.c-185-};\n--\ndrivers/vdpa/vdpa_user/vduse_dev.c=2191=static bool features_is_valid(struct vduse_dev_config config)\n--\ndrivers/vdpa/vdpa_user/vduse_dev.c-2196-\t/ Now we only support read-only configuration space /\ndrivers/vdpa/vdpa_user/vduse_dev.c:2197:\tif ((config-\u003edevice_id == VIRTIO_ID_BLOCK) \u0026\u0026\ndrivers/vdpa/vdpa_user/vduse_dev.c-2198-\t\t\t(config-\u003efeatures \u0026 BIT_ULL(VIRTIO_BLK_F_CONFIG_WCE)))\ndrivers/vdpa/vdpa_user/vduse_dev.c-2199-\t\treturn false;\ndrivers/vdpa/vdpa_user/vduse_dev.c:2200:\telse if ((config-\u003edevice_id == VIRTIO_ID_NET) \u0026\u0026\ndrivers/vdpa/vdpa_user/vduse_dev.c-2201-\t\t\t(config-\u003efeatures \u0026 BIT_ULL(VIRTIO_NET_F_CTRL_VQ)))\n--\ndrivers/vdpa/vdpa_user/vduse_dev.c-2203-\ndrivers/vdpa/vdpa_user/vduse_dev.c:2204:\tif ((config-\u003edevice_id == VIRTIO_ID_NET) \u0026\u0026\ndrivers/vdpa/vdpa_user/vduse_dev.c-2205-\t\t\t!(config-\u003efeatures \u0026 BIT_ULL(VIRTIO_F_VERSION_1)))\n--\ndrivers/vdpa/vdpa_user/vduse_dev.c=2325=static int vduse_create_dev(struct vduse_dev_config config,\n--\ndrivers/vdpa/vdpa_user/vduse_dev.c-2332-\tret = -EPERM;\ndrivers/vdpa/vdpa_user/vduse_dev.c:2333:\tif ((config-\u003edevice_id == VIRTIO_ID_NET) \u0026\u0026 !capable(CAP_NET_ADMIN))\ndrivers/vdpa/vdpa_user/vduse_dev.c-2334-\t\tgoto err;\n--\ndrivers/vdpa/vdpa_user/vduse_dev.c=2650=static struct virtio_device_id id_table[] = {\ndrivers/vdpa/vdpa_user/vduse_dev.c:2651:\t{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },\ndrivers/vdpa/vdpa_user/vduse_dev.c:2652:\t{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },\ndrivers/vdpa/vdpa_user/vduse_dev.c-2653-\t{ 0 },\n" }
57/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 51389 output: 20 thoughts: 133 Thoughts: Here's my thought process, as if I were analyzing this code: Diving into the Device Usage and Remote Processor Messaging Okay, let's get down to brass tacks. I'm looking at `vduse_dev.c`. Right away, I see `allowed_device_id[] = { VIRTIO_ID_BLOCK, VIRTIO_ID_NET, VIRTIO_ID_FS }`. I'm comparing that to the capabilities of vdpasim, and I'm noting the mismatch: it appears vdpasim only handles networking and block devices. Interesting. Something's potentially missing here or a configuration that isn't immediately obvious. Hold on a second, though! My intuition is telling me there might be something else at play here. Since this smells like some kind of remote processing situation, I should really be looking at the bigger picture and the potential for other drivers that aren't immediately exposed in this file. Since this seems like an interface with a remote processor, I'll search for "rpmsg" throughout the whole kernel. Let's see if we're dealing with Remote Processor Messaging. Alright, let's expand the search. I want to see how these remote processing mechanisms are registered and instantiated. I'll search for calls to `rpmsg_create_channel`, `rpmsg_register_device`, and `rpmsg_register_driver` in the kernel. This should reveal the architecture of how these virtual devices are managed. I'll focus on `rpmsg_register_driver` first, since that seems like the key entry point for this sort of driver registration and discovery.
58/2	2026/10/26 11:48	tool	grepper	0m Error: no matches Args: { "Expression": "rpmsg_register_driver" } Results: { "error": "no matches" }
59/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 51904 output: 20 thoughts: 13 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Analyzing the Landscape: Targeting `register_rpmsg_driver` Alright, let's dive in. My immediate instinct, and likely yours as well, is to begin with a targeted search for `register_rpmsg_driver`. I need to get a clear understanding of the RPMSG driver registration process. This is the lynchpin, the starting point for understanding how these remote processor message (RPMSG) interactions are initiated within the system. We know this function is crucial for integrating RPMSG functionality, but I need to quickly recall precisely how the driver model interacts here. I'm focusing on the registration aspect first, as it's foundational and dictates what comes next. What's it doing? What's it expecting? What side effects does it have? I want the full context. It's the best way to get a solid handle on the overall architecture. I anticipate this will lead me to the core driver structure, associated device initialization, and likely, a few key data structures that handle the RPMSG endpoints.
60/2	2026/10/26 11:48	tool	grepper	0m Args: { "Expression": "register_rpmsg_driver" } Results: { "Output": "Documentation/staging/rpmsg.rst=195=to an rpmsg endpoint that was previously created with rpmsg_create_ept().\n--\nDocumentation/staging/rpmsg.rst-198-\nDocumentation/staging/rpmsg.rst:199: int register_rpmsg_driver(struct rpmsg_driver rpdrv);\nDocumentation/staging/rpmsg.rst-200-\n--\nDocumentation/staging/rpmsg.rst=206=be probed with.\n--\nDocumentation/staging/rpmsg.rst-209-\nDocumentation/staging/rpmsg.rst:210: void unregister_rpmsg_driver(struct rpmsg_driver rpdrv);\nDocumentation/staging/rpmsg.rst-211-\n--\ndrivers/cdx/controller/cdx_rpmsg.c=169=int cdx_setup_rpmsg(struct platform_device pdev)\n--\ndrivers/cdx/controller/cdx_rpmsg.c-186-\tINIT_WORK(\u0026cdx_mcdi-\u003ework, cdx_rpmsg_post_probe_work);\ndrivers/cdx/controller/cdx_rpmsg.c:187:\tret = register_rpmsg_driver(\u0026cdx_rpmsg_driver);\ndrivers/cdx/controller/cdx_rpmsg.c-188-\tif (ret) {\n--\ndrivers/cdx/controller/cdx_rpmsg.c=197=void cdx_destroy_rpmsg(struct platform_device pdev)\ndrivers/cdx/controller/cdx_rpmsg.c-198-{\ndrivers/cdx/controller/cdx_rpmsg.c:199:\tunregister_rpmsg_driver(\u0026cdx_rpmsg_driver);\ndrivers/cdx/controller/cdx_rpmsg.c-200-\n--\ndrivers/edac/versalnet_edac.c=883=static int mc_probe(struct platform_device pdev)\n--\ndrivers/edac/versalnet_edac.c-913-\ndrivers/edac/versalnet_edac.c:914:\trc = register_rpmsg_driver(\u0026amd_rpmsg_driver);\ndrivers/edac/versalnet_edac.c-915-\tif (rc) {\n--\ndrivers/edac/versalnet_edac.c-936-err_unreg:\ndrivers/edac/versalnet_edac.c:937:\tunregister_rpmsg_driver(\u0026amd_rpmsg_driver);\ndrivers/edac/versalnet_edac.c-938-\n--\ndrivers/edac/versalnet_edac.c=948=static void mc_remove(struct platform_device pdev)\n--\ndrivers/edac/versalnet_edac.c-951-\ndrivers/edac/versalnet_edac.c:952:\tunregister_rpmsg_driver(\u0026amd_rpmsg_driver);\ndrivers/edac/versalnet_edac.c-953-\tremove_versalnet(priv);\n--\ndrivers/media/platform/st/sti/delta/delta-ipc.c=581=int delta_ipc_init(struct delta_dev delta)\n--\ndrivers/media/platform/st/sti/delta/delta-ipc.c-584-\ndrivers/media/platform/st/sti/delta/delta-ipc.c:585:\treturn register_rpmsg_driver(\u0026delta-\u003erpmsg_driver);\ndrivers/media/platform/st/sti/delta/delta-ipc.c-586-}\n--\ndrivers/media/platform/st/sti/delta/delta-ipc.c=588=void delta_ipc_exit(struct delta_dev delta)\ndrivers/media/platform/st/sti/delta/delta-ipc.c-589-{\ndrivers/media/platform/st/sti/delta/delta-ipc.c:590:\tunregister_rpmsg_driver(\u0026delta-\u003erpmsg_driver);\ndrivers/media/platform/st/sti/delta/delta-ipc.c-591-}\n--\ndrivers/misc/fastrpc.c=2801=static int fastrpc_init(void)\n--\ndrivers/misc/fastrpc.c-2810-\ndrivers/misc/fastrpc.c:2811:\tret = register_rpmsg_driver(\u0026fastrpc_driver);\ndrivers/misc/fastrpc.c-2812-\tif (ret \u003c 0) {\n--\ndrivers/misc/fastrpc.c=2822=static void fastrpc_exit(void)\n--\ndrivers/misc/fastrpc.c-2824-\tplatform_driver_unregister(\u0026fastrpc_cb_driver);\ndrivers/misc/fastrpc.c:2825:\tunregister_rpmsg_driver(\u0026fastrpc_driver);\ndrivers/misc/fastrpc.c-2826-}\n--\ndrivers/rpmsg/rpmsg_char.c=562=static int rpmsg_chrdev_init(void)\n--\ndrivers/rpmsg/rpmsg_char.c-571-\ndrivers/rpmsg/rpmsg_char.c:572:\tret = register_rpmsg_driver(\u0026rpmsg_chrdev_driver);\ndrivers/rpmsg/rpmsg_char.c-573-\tif (ret \u003c 0) {\n--\ndrivers/rpmsg/rpmsg_char.c=587=static void rpmsg_chrdev_exit(void)\ndrivers/rpmsg/rpmsg_char.c-588-{\ndrivers/rpmsg/rpmsg_char.c:589:\tunregister_rpmsg_driver(\u0026rpmsg_chrdev_driver);\ndrivers/rpmsg/rpmsg_char.c-590-\tunregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);\n--\ndrivers/rpmsg/rpmsg_core.c=581=EXPORT_SYMBOL(rpmsg_unregister_device);\n--\ndrivers/rpmsg/rpmsg_core.c-583-/*\ndrivers/rpmsg/rpmsg_core.c:584: __register_rpmsg_driver() - register an rpmsg driver with the rpmsg bus\ndrivers/rpmsg/rpmsg_core.c-585- * @rpdrv: pointer to a struct rpmsg_driver\n--\ndrivers/rpmsg/rpmsg_core.c-589- /\ndrivers/rpmsg/rpmsg_core.c:590:int __register_rpmsg_driver(struct rpmsg_driver rpdrv, struct module owner)\ndrivers/rpmsg/rpmsg_core.c-591-{\n--\ndrivers/rpmsg/rpmsg_core.c-595-}\ndrivers/rpmsg/rpmsg_core.c:596:EXPORT_SYMBOL(__register_rpmsg_driver);\ndrivers/rpmsg/rpmsg_core.c-597-\ndrivers/rpmsg/rpmsg_core.c-598-/\ndrivers/rpmsg/rpmsg_core.c:599: unregister_rpmsg_driver() - unregister an rpmsg driver from the rpmsg bus\ndrivers/rpmsg/rpmsg_core.c-600- * @rpdrv: pointer to a struct rpmsg_driver\ndrivers/rpmsg/rpmsg_core.c-601- /\ndrivers/rpmsg/rpmsg_core.c:602:void unregister_rpmsg_driver(struct rpmsg_driver rpdrv)\ndrivers/rpmsg/rpmsg_core.c-603-{\n--\ndrivers/rpmsg/rpmsg_core.c-605-}\ndrivers/rpmsg/rpmsg_core.c:606:EXPORT_SYMBOL(unregister_rpmsg_driver);\ndrivers/rpmsg/rpmsg_core.c-607-\n--\ndrivers/rpmsg/rpmsg_ctrl.c=216=static int rpmsg_ctrldev_init(void)\n--\ndrivers/rpmsg/rpmsg_ctrl.c-225-\ndrivers/rpmsg/rpmsg_ctrl.c:226:\tret = register_rpmsg_driver(\u0026rpmsg_ctrldev_driver);\ndrivers/rpmsg/rpmsg_ctrl.c-227-\tif (ret \u003c 0) {\n--\ndrivers/rpmsg/rpmsg_ctrl.c=236=static void rpmsg_ctrldev_exit(void)\ndrivers/rpmsg/rpmsg_ctrl.c-237-{\ndrivers/rpmsg/rpmsg_ctrl.c:238:\tunregister_rpmsg_driver(\u0026rpmsg_ctrldev_driver);\ndrivers/rpmsg/rpmsg_ctrl.c-239-\tunregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);\n--\ndrivers/rpmsg/rpmsg_ns.c=103=static int rpmsg_ns_init(void)\n--\ndrivers/rpmsg/rpmsg_ns.c-106-\ndrivers/rpmsg/rpmsg_ns.c:107:\tret = register_rpmsg_driver(\u0026rpmsg_ns_driver);\ndrivers/rpmsg/rpmsg_ns.c-108-\tif (ret \u003c 0)\n--\ndrivers/rpmsg/rpmsg_ns.c=115=static void rpmsg_ns_exit(void)\ndrivers/rpmsg/rpmsg_ns.c-116-{\ndrivers/rpmsg/rpmsg_ns.c:117:\tunregister_rpmsg_driver(\u0026rpmsg_ns_driver);\ndrivers/rpmsg/rpmsg_ns.c-118-}\n--\ndrivers/soc/qcom/apr.c=699=static int __init apr_init(void)\n--\ndrivers/soc/qcom/apr.c-704-\tif (!ret)\ndrivers/soc/qcom/apr.c:705:\t\tret = register_rpmsg_driver(\u0026packet_router_driver);\ndrivers/soc/qcom/apr.c-706-\telse\n--\ndrivers/soc/qcom/apr.c=712=static void __exit apr_exit(void)\n--\ndrivers/soc/qcom/apr.c-714-\tbus_unregister(\u0026aprbus);\ndrivers/soc/qcom/apr.c:715:\tunregister_rpmsg_driver(\u0026packet_router_driver);\ndrivers/soc/qcom/apr.c-716-}\n--\ndrivers/soc/qcom/pmic_glink.c=424=static int pmic_glink_init(void)\n--\ndrivers/soc/qcom/pmic_glink.c-431-\ndrivers/soc/qcom/pmic_glink.c:432:\tret = register_rpmsg_driver(\u0026pmic_glink_rpmsg_driver);\ndrivers/soc/qcom/pmic_glink.c-433-\tif (ret \u003c 0) {\n--\ndrivers/soc/qcom/pmic_glink.c=442=static void pmic_glink_exit(void)\ndrivers/soc/qcom/pmic_glink.c-443-{\ndrivers/soc/qcom/pmic_glink.c:444:\tunregister_rpmsg_driver(\u0026pmic_glink_rpmsg_driver);\ndrivers/soc/qcom/pmic_glink.c-445-\tplatform_driver_unregister(\u0026pmic_glink_driver);\n--\ndrivers/soc/qcom/smd-rpm.c=258=static int __init qcom_smd_rpm_init(void)\ndrivers/soc/qcom/smd-rpm.c-259-{\ndrivers/soc/qcom/smd-rpm.c:260:\treturn register_rpmsg_driver(\u0026qcom_smd_rpm_driver);\ndrivers/soc/qcom/smd-rpm.c-261-}\n--\ndrivers/soc/qcom/smd-rpm.c=264=static void __exit qcom_smd_rpm_exit(void)\ndrivers/soc/qcom/smd-rpm.c-265-{\ndrivers/soc/qcom/smd-rpm.c:266:\tunregister_rpmsg_driver(\u0026qcom_smd_rpm_driver);\ndrivers/soc/qcom/smd-rpm.c-267-}\n--\ndrivers/tty/rpmsg_tty.c=231=static int __init rpmsg_tty_init(void)\n--\ndrivers/tty/rpmsg_tty.c-257-\ndrivers/tty/rpmsg_tty.c:258:\tret = register_rpmsg_driver(\u0026rpmsg_tty_rpmsg_drv);\ndrivers/tty/rpmsg_tty.c-259-\tif (ret \u003c 0) {\n--\ndrivers/tty/rpmsg_tty.c=275=static void __exit rpmsg_tty_exit(void)\ndrivers/tty/rpmsg_tty.c-276-{\ndrivers/tty/rpmsg_tty.c:277:\tunregister_rpmsg_driver(\u0026rpmsg_tty_rpmsg_drv);\ndrivers/tty/rpmsg_tty.c-278-\ttty_unregister_driver(rpmsg_tty_driver);\n--\ninclude/linux/rpmsg.h=172=int rpmsg_unregister_device(struct device parent,\ninclude/linux/rpmsg.h-173-\t\t\t struct rpmsg_channel_info chinfo);\ninclude/linux/rpmsg.h:174:int __register_rpmsg_driver(struct rpmsg_driver drv, struct module owner);\ninclude/linux/rpmsg.h:175:void unregister_rpmsg_driver(struct rpmsg_driver drv);\ninclude/linux/rpmsg.h-176-void rpmsg_destroy_ept(struct rpmsg_endpoint );\n--\ninclude/linux/rpmsg.h=207=static inline int rpmsg_unregister_device(struct device parent,\n--\ninclude/linux/rpmsg.h-215-\ninclude/linux/rpmsg.h:216:static inline int __register_rpmsg_driver(struct rpmsg_driver drv,\ninclude/linux/rpmsg.h-217-\t\t\t\t\t struct module owner)\n--\ninclude/linux/rpmsg.h-224-\ninclude/linux/rpmsg.h:225:static inline void unregister_rpmsg_driver(struct rpmsg_driver drv)\ninclude/linux/rpmsg.h-226-{\n--\ninclude/linux/rpmsg.h=301=static inline int rpmsg_set_flow_control(struct rpmsg_endpoint ept, bool pause, u32 dst)\n--\ninclude/linux/rpmsg.h-311-/ use a macro to avoid include chaining to get THIS_MODULE */\ninclude/linux/rpmsg.h:312:#define register_rpmsg_driver(drv) \\\ninclude/linux/rpmsg.h:313:\t__register_rpmsg_driver(drv, THIS_MODULE)\ninclude/linux/rpmsg.h-314-\n--\ninclude/linux/rpmsg.h-323-#define module_rpmsg_driver(__rpmsg_driver) \\\ninclude/linux/rpmsg.h:324:\tmodule_driver(__rpmsg_driver, register_rpmsg_driver, \\\ninclude/linux/rpmsg.h:325:\t\t\tunregister_rpmsg_driver)\ninclude/linux/rpmsg.h-326-\n" }
61/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 55971 output: 32 thoughts: 701 Thoughts: Analyzing the Remote Processor Messaging (rpmsg) System Okay, let's break this down systematically. I see that `register_rpmsg_driver` is a key function, and a lot of different drivers call it: `cdx_rpmsg`, `versalnet_edac`, `delta-ipc`, `fastrpc`, the `rpmsg` core drivers like `rpmsg_char`, `rpmsg_ctrl`, `rpmsg_ns`, and then drivers related to Qualcomm and Mediatek platforms (`apr`, `pmic_glink`, `smd-rpm`), and finally `rpmsg_tty`. That tells me these are all drivers that are registering themselves to the rpmsg bus. Now, the question is, what actually creates rpmsg devices on this bus? From the data, it looks like only a few specific drivers: `mtk_rpmsg`, `qcom_glink`, `qcom_smd`, and, crucially, `virtio_rpmsg_bus`. I'm starting to see a pattern here. The `virtio_rpmsg_bus` is interesting, and it looks like `virtio_ipc_driver` is related to it, as its `id_table` lists `VIRTIO_ID_RPMSG`. The next question is, where is a `virtio_device` actually created with this ID (7)? My earlier searches didn't turn up a direct answer outside the `virtio_rpmsg_bus` and the header file. Let's dig deeper to see where `rproc_add_virtio_dev` is called, which looks like the function that adds a virtio device to the remoteproc subsystem. Searching reveals it's in `drivers/remoteproc/remoteproc_virtio.c`. The `rproc_vdev_do_start` function uses `rproc_add_virtio_dev` to add a virtio device. The device ID comes from `rvdev->id`. So, I need to figure out where that `rvdev->id` is getting assigned. I'll need to check the remoteproc core code now to follow where that comes from.
62/2	2026/10/26 11:48	tool	grepper	0m Args: { "Expression": "rvdev-\u003eid", "PathPrefixes": [ "drivers/remoteproc/" ] } Results: { "Output": "drivers/remoteproc/remoteproc_virtio.c=499=static int rproc_vdev_do_start(struct rproc_subdev subdev)\n--\ndrivers/remoteproc/remoteproc_virtio.c-502-\ndrivers/remoteproc/remoteproc_virtio.c:503:\treturn rproc_add_virtio_dev(rvdev, rvdev-\u003eid);\ndrivers/remoteproc/remoteproc_virtio.c-504-}\n--\ndrivers/remoteproc/remoteproc_virtio.c=517=static int rproc_virtio_probe(struct platform_device pdev)\n--\ndrivers/remoteproc/remoteproc_virtio.c-532-\ndrivers/remoteproc/remoteproc_virtio.c:533:\trvdev-\u003eid = rvdev_data-\u003eid;\ndrivers/remoteproc/remoteproc_virtio.c-534-\trvdev-\u003erproc = rproc;\n" }
63/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 57455 output: 32 thoughts: 44 Thoughts: Okay, let's see. My initial thought is, "Ah, look at this line: `rvdev_data->id`. Interesting." I immediately start dissecting this, the expert's intuition is kicking in; where does this variable, `rvdev_data`, actually get initialized? It's the key to understanding the context. I need to trace its origins. The next step is obvious. I'll jump straight to a search. I'll focus my investigation within the `drivers/remoteproc/` directory. That seems like the most logical location, given the context implied by `rvdev_data` and the overall code structure. Finding the initialization will give me the crucial context I need to fully grasp this code segment's purpose and functionality.
64/2	2026/10/26 11:48	tool	grepper	0m Args: { "Expression": "rvdev_data", "PathPrefixes": [ "drivers/remoteproc/" ] } Results: { "Output": "drivers/remoteproc/remoteproc_core.c=471=static int rproc_handle_vdev(struct rproc rproc, void ptr,\n--\ndrivers/remoteproc/remoteproc_core.c-477-\tsize_t rsc_size;\ndrivers/remoteproc/remoteproc_core.c:478:\tstruct rproc_vdev_data rvdev_data;\ndrivers/remoteproc/remoteproc_core.c-479-\tstruct platform_device pdev;\n--\ndrivers/remoteproc/remoteproc_core.c-502-\ndrivers/remoteproc/remoteproc_core.c:503:\trvdev_data.id = rsc-\u003eid;\ndrivers/remoteproc/remoteproc_core.c:504:\trvdev_data.index = rproc-\u003enb_vdev++;\ndrivers/remoteproc/remoteproc_core.c:505:\trvdev_data.rsc_offset = offset;\ndrivers/remoteproc/remoteproc_core.c:506:\trvdev_data.rsc = rsc;\ndrivers/remoteproc/remoteproc_core.c-507-\n--\ndrivers/remoteproc/remoteproc_core.c-509-\t When there is more than one remote processor, rproc-\u003enb_vdev number is\ndrivers/remoteproc/remoteproc_core.c:510:\t * same for each separate instances of \"rproc\". If rvdev_data.index is used\ndrivers/remoteproc/remoteproc_core.c-511-\t * as device id, then we get duplication in sysfs, so need to use\n--\ndrivers/remoteproc/remoteproc_core.c-513-\t /\ndrivers/remoteproc/remoteproc_core.c:514:\tpdev = platform_device_register_data(dev, \"rproc-virtio\", PLATFORM_DEVID_AUTO, \u0026rvdev_data,\ndrivers/remoteproc/remoteproc_core.c:515:\t\t\t\t\t sizeof(rvdev_data));\ndrivers/remoteproc/remoteproc_core.c-516-\tif (IS_ERR(pdev)) {\n--\ndrivers/remoteproc/remoteproc_virtio.c=517=static int rproc_virtio_probe(struct platform_device pdev)\n--\ndrivers/remoteproc/remoteproc_virtio.c-519-\tstruct device dev = \u0026pdev-\u003edev;\ndrivers/remoteproc/remoteproc_virtio.c:520:\tstruct rproc_vdev_data rvdev_data = dev-\u003eplatform_data;\ndrivers/remoteproc/remoteproc_virtio.c-521-\tstruct rproc_vdev rvdev;\n--\ndrivers/remoteproc/remoteproc_virtio.c-525-\ndrivers/remoteproc/remoteproc_virtio.c:526:\tif (!rvdev_data)\ndrivers/remoteproc/remoteproc_virtio.c-527-\t\treturn -EINVAL;\n--\ndrivers/remoteproc/remoteproc_virtio.c-532-\ndrivers/remoteproc/remoteproc_virtio.c:533:\trvdev-\u003eid = rvdev_data-\u003eid;\ndrivers/remoteproc/remoteproc_virtio.c-534-\trvdev-\u003erproc = rproc;\ndrivers/remoteproc/remoteproc_virtio.c:535:\trvdev-\u003eindex = rvdev_data-\u003eindex;\ndrivers/remoteproc/remoteproc_virtio.c-536-\n--\ndrivers/remoteproc/remoteproc_virtio.c-552-\ndrivers/remoteproc/remoteproc_virtio.c:553:\trsc = rvdev_data-\u003ersc;\ndrivers/remoteproc/remoteproc_virtio.c-554-\n--\ndrivers/remoteproc/remoteproc_virtio.c-562-\t/ remember the resource offset*/\ndrivers/remoteproc/remoteproc_virtio.c:563:\trvdev-\u003ersc_offset = rvdev_data-\u003ersc_offset;\ndrivers/remoteproc/remoteproc_virtio.c-564-\n" }
65/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 58851 output: 41 thoughts: 340 Thoughts: My Remoteproc Driver Analysis Okay, so `rproc_handle_vdev` is the crucial function here, parsing the resource table during the remoteproc device boot. And, of course, a remoteproc driver creates an `rproc` instance. Let's list the relevant drivers; I see TI K3, i.MX, Qualcomm Hexagon/Modem, MediaTek SCP, Renesas R-Car, Xilinx ZynqMP, AM33xx, OMAP, DA8xx, Meson, Ingenic, ST, and AMD MicroBlaze V. Now, a key question: Can any of these remoteproc drivers probe without physical hardware, say, via the SoC's DT node? Absolutely, they're all platform drivers, matching OF compatible strings, like `st,stm32mp1-m4`, `ti,omap4-rproc`, `qcom,q6v5`, and `fsl,imx7d-rproc`, among others. But, can a standard amd64 QEMU configuration, like PC/Q35 with ACPI and PCI, use any of these? No, because it doesn't utilize Device Tree for ARM/DSP/remoteproc coprocessors. Now, an interesting thought – could QEMU emulate a PCI remoteproc device? Well, none of the remoteproc drivers are PCI drivers. I need to confirm this: let me grep the `drivers/remoteproc/` directory for `pci_register_driver`.
66/2	2026/10/26 11:48	tool	grepper	0m Error: no matches Args: { "Expression": "pci_register_driver\|module_pci_driver", "PathPrefixes": [ "drivers/remoteproc/" ] } Results: { "error": "no matches" }
67/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 59586 output: 29 thoughts: 57 Thoughts: Okay, let's see... Remote Processor Driver Investigation Hmm, none of these remoteproc drivers seem to be PCI-based. That's unexpected. Wait a minute... What about CDX? I've got to be missing something. Let me double-check the code in `drivers/cdx/controller/cdx_rpmsg.c`. Okay, let's take a look at `drivers/cdx/Kconfig` to figure out what CDX actually is. I need to understand the context here before I proceed. I'm sure it will be obvious once I refresh my memory of the architecture.
68/2	2026/10/26 11:48	tool	grepper	0m Args: { "Expression": "config CDX", "PathPrefixes": [ "drivers/cdx/" ] } Results: { "Output": "drivers/cdx/Kconfig-7-\ndrivers/cdx/Kconfig:8:config CDX_BUS\ndrivers/cdx/Kconfig-9-\tbool \"CDX Bus driver\"\n--\ndrivers/cdx/controller/Kconfig=8=if CDX_BUS\ndrivers/cdx/controller/Kconfig-9-\ndrivers/cdx/controller/Kconfig:10:config CDX_CONTROLLER\ndrivers/cdx/controller/Kconfig-11-\ttristate \"CDX bus controller\"\n" }
69/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 59942 output: 33 thoughts: 13 Thoughts: Here's my take on those thoughts, tailored for an expert like yourself: Diving into the CDX Kconfig Alright, let's get down to brass tacks and crack open the `drivers/cdx/Kconfig` file. I immediately start thinking about how this configuration file dictates the build process and what features related to the CDX (likely a specific hardware or software component, given the context) can be enabled or disabled. My mind races, considering the dependencies it likely defines: what other modules or features must be present for the CDX driver to function? What optional features are controlled here? I’m already anticipating the structure – expect to see the standard `config` blocks, likely with help text that, hopefully, clarifies the purpose of each option. I'll be looking for things like: * Dependencies: Are there `depends on` statements? What other subsystems are tightly coupled with the CDX driver? This tells me the wider architecture. * Default Values: What are the default settings? Are they sensible? Are they intended for the most common use case, or for development? * Tristates: `bool`, `tristate`, or `int` options – what level of control does this Kconfig expose? Could this allow users to fully disable the CDX driver (which often is important for resource optimization in embedded systems)? * Prominent Features: How can I tell which parts of this driver are meant to be configured? * Options for advanced configuration: are there more nuanced and detailed options for power users? I'm ready to dig in and understand how this Kconfig is shaping the CDX driver's configurability, and ultimately, its role in the overall system. Time to see what we've got!
70/2	2026/10/26 11:48	tool	read-file	0m Args: { "File": "drivers/cdx/Kconfig", "FirstLine": 1, "LineCount": 40 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0\n 2:\t#\n 3:\t# CDX bus configuration\n 4:\t#\n 5:\t# Copyright (C) 2022-2023, Advanced Micro Devices, Inc.\n 6:\t#\n 7:\t\n 8:\tconfig CDX_BUS\n 9:\t\tbool \"CDX Bus driver\"\n 10:\t\tdepends on OF \u0026\u0026 ARM64 \|\| COMPILE_TEST\n 11:\t\thelp\n 12:\t\t Driver to enable Composable DMA Transfer(CDX) Bus. CDX bus\n 13:\t\t exposes Fabric devices which uses composable DMA IP to the\n 14:\t\t APU. CDX bus provides a mechanism for scanning and probing\n 15:\t\t of CDX devices. CDX devices are memory mapped on system bus\n 16:\t\t for embedded CPUs. CDX bus uses CDX controller and firmware\n 17:\t\t to scan these CDX devices.\n 18:\t\n 19:\tsource \"drivers/cdx/controller/Kconfig\"\n" }
71/2	2026/10/26 11:48	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 60644 output: 39 thoughts: 1077 Thoughts: RPMSG Device Creation Deep Dive Okay, so `CDX_BUS` depends on `OF && ARM64 \|\| COMPILE_TEST`, that much is clear. But I'm thinking about the user-space interface, specifically `RPMSG_CHAR`. Can character devices be dynamically created, or are they statically defined? I need to understand if `rpmsg_char` or `rpmsg_ctrl` devices can be created through sysfs, configfs, or some other mechanism. Let's dig into the code. First, I looked at `drivers/rpmsg/rpmsg_char.c`. `rpmsg_chrdev_init` is a key function there. I see it allocates a character device region and registers the `rpmsg_chrdev_driver` with the `rpmsg_bus`. Crucially, it doesn't create any devices under `/dev` at this stage. It's just setting up the major number. The actual device creation in `/dev` happens within `rpmsg_chrdev_eptdev_add()`, but that function is only called from `rpmsg_chrdev_probe()` when an `rpmsg_device` matches the `rpmsg_chrdev_driver` or through the `RPMSG_CREATE_EPT_IOCTL` command. Now, let's turn our attention to the controller device and `/dev/rpmsg_ctrlX`. I checked `drivers/rpmsg/rpmsg_ctrl.c`. `rpmsg_ctrldev_init` is similar; it allocates a major number and registers the `rpmsg_ctrldev_driver`. But it doesn't create the device under `/dev` either. The creation of `/dev/rpmsg_ctrlX` happens exclusively in `rpmsg_ctrldev_probe()`. This function allocates a `rpmsg_ctrldev` structure, initializes its device, assigns a minor number, and then, very importantly, calls `cdev_device_add()` to create the character device. `rpmsg_ctrldev_probe` is called only when an `rpmsg_device` on the `rpmsg_bus` matches the "rpmsg_ctrl" driver. So how does this "rpmsg_ctrl" `rpmsg_device` get created? It's done through `rpmsg_ctrldev_register_device(rpdev)`. Which is called by Qualcomm hardware modules and via `rpmsg_virtio_add_ctrl_dev()` function. So, it seems to me that to get an `rpmsg_ctrlX` or `rpmsg_charX` device, I need the underlying bus to create it. Can I trigger the device creation via sysfs driver binding/unbinding or bus manipulation? Let's check `drivers/rpmsg/rpmsg_core.c` to confirm.
72/2	2026/10/26 11:49	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_core.c", "FirstLine": 480, "LineCount": 90 } Results: { "Contents": " 480:\t\n 481:\t\treturn 0;\n 482:\t\n 483:\tremove_rpdev:\n 484:\t\tif (rpdrv-\u003eremove)\n 485:\t\t\trpdrv-\u003eremove(rpdev);\n 486:\tdestroy_ept:\n 487:\t\tif (ept)\n 488:\t\t\trpmsg_destroy_ept(ept);\n 489:\tout:\n 490:\t\treturn err;\n 491:\t}\n 492:\t\n 493:\tstatic void rpmsg_dev_remove(struct device dev)\n 494:\t{\n 495:\t\tstruct rpmsg_device rpdev = to_rpmsg_device(dev);\n 496:\t\tstruct rpmsg_driver rpdrv = to_rpmsg_driver(rpdev-\u003edev.driver);\n 497:\t\n 498:\t\tif (rpdev-\u003eops-\u003eannounce_destroy)\n 499:\t\t\trpdev-\u003eops-\u003eannounce_destroy(rpdev);\n 500:\t\n 501:\t\tif (rpdrv-\u003eremove)\n 502:\t\t\trpdrv-\u003eremove(rpdev);\n 503:\t\n 504:\t\tif (rpdev-\u003eept)\n 505:\t\t\trpmsg_destroy_ept(rpdev-\u003eept);\n 506:\t}\n 507:\t\n 508:\tstatic const struct bus_type rpmsg_bus = {\n 509:\t\t.name\t\t= \"rpmsg\",\n 510:\t\t.match\t\t= rpmsg_dev_match,\n 511:\t\t.dev_groups\t= rpmsg_dev_groups,\n 512:\t\t.driver_override = true,\n 513:\t\t.uevent\t\t= rpmsg_uevent,\n 514:\t\t.probe\t\t= rpmsg_dev_probe,\n 515:\t\t.remove\t\t= rpmsg_dev_remove,\n 516:\t};\n 517:\t\n 518:\t/\n 519:\t * A helper for registering rpmsg device with driver override and name.\n 520:\t * Drivers should not be using it, but instead rpmsg_register_device().\n 521:\t /\n 522:\tint rpmsg_register_device_override(struct rpmsg_device rpdev,\n 523:\t\t\t\t\t const char driver_override)\n 524:\t{\n 525:\t\tstruct device dev = \u0026rpdev-\u003edev;\n 526:\t\tint ret;\n 527:\t\n 528:\t\tif (driver_override)\n 529:\t\t\tstrscpy_pad(rpdev-\u003eid.name, driver_override, RPMSG_NAME_SIZE);\n 530:\t\n 531:\t\tdev_set_name(dev, \"%s.%s.%d.%d\", dev_name(dev-\u003eparent),\n 532:\t\t\t rpdev-\u003eid.name, rpdev-\u003esrc, rpdev-\u003edst);\n 533:\t\n 534:\t\tdev-\u003ebus = \u0026rpmsg_bus;\n 535:\t\n 536:\t\tdevice_initialize(dev);\n 537:\t\tif (driver_override) {\n 538:\t\t\tret = device_set_driver_override(dev, driver_override);\n 539:\t\t\tif (ret) {\n 540:\t\t\t\tdev_err(dev, \"device_set_driver_override() failed: %d\\n\", ret);\n 541:\t\t\t\tput_device(dev);\n 542:\t\t\t\treturn ret;\n 543:\t\t\t}\n 544:\t\t}\n 545:\t\n 546:\t\tret = device_add(dev);\n 547:\t\tif (ret) {\n 548:\t\t\tdev_err(dev, \"device_add failed: %d\\n\", ret);\n 549:\t\t\tput_device(dev);\n 550:\t\t}\n 551:\t\n 552:\t\treturn ret;\n 553:\t}\n 554:\tEXPORT_SYMBOL(rpmsg_register_device_override);\n 555:\t\n 556:\tint rpmsg_register_device(struct rpmsg_device rpdev)\n 557:\t{\n 558:\t\treturn rpmsg_register_device_override(rpdev, NULL);\n 559:\t}\n 560:\tEXPORT_SYMBOL(rpmsg_register_device);\n 561:\t\n 562:\t/\n 563:\t * find an existing channel using its name + address properties,\n 564:\t * and destroy it\n 565:\t /\n 566:\tint rpmsg_unregister_device(struct device parent,\n 567:\t\t\t\t struct rpmsg_channel_info chinfo)\n 568:\t{\n 569:\t\tstruct device dev;\n" }
73/2	2026/10/26 11:49	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 63640 output: 37 thoughts: 758 Thoughts: My Investigation into RPMSG Device Creation Okay, here's the situation. I'm trying to figure out how an rpmsg device, specifically one corresponding to `VIRTIO_ID_RPMSG`, is created within the Linux kernel. First thought: can it be done via `sysfs` and the `new_device` mechanism? Let's see if the `rpmsg_bus` bus type has the required elements to accomplish this, so let me quickly review the `struct bus_type rpmsg_bus` definition. Nope, doesn't look like it. No `new_device` there, nor any associated attributes that would enable that sort of creation. Alright, so not the direct bus implementation. What about a virtio-based creation? Could the `virtio_rpmsg_bus` offer something? And further, could a `virtio` device, specifically one with the rpmsg ID, be created via, say, `virtio_pci` or `virtio_mmio`? Time to dig into how `virtio` devices are created in the Linux kernel. Focusing on `virtio_pci`, I recall that the PCI device ID would have to match `VIRTIO_PCI_VENDOR` (0x1af4), and the device ID would be in the range 0x1000..0x107f. And, with virtio 1.0, the PCI device ID is constructed as 0x1040 + Virtio Device ID. So, for `VIRTIO_ID_RPMSG` (7), the PCI Device ID should be 0x1047. The next question: Can QEMU create a generic virtio PCI device with an arbitrary virtio device ID? Hmm, no, QEMU's PCI devices seem to be hardcoded in its C source. There's no such thing as `virtio-rpmsg-pci`. Okay, next candidate: `virtio_mmio`. These can be specified on the kernel command line, right? Specifically, in this format: `virtio_mmio.device=<size>@<baseaddr>:<irq>[:<id>]`! This seems promising. The important question then: Does syzkaller, during its testing, utilize `virtio_mmio.device=...` with the specific ID 7 (for rpmsg)? No, it seems syzkaller runs QEMU with its standard command line flags. Nothing specific there. Another thought: Can userspace create a virtio device? That brings me to `CONFIG_VHOST_VDPA` or `CONFIG_VDPA`. Can userspace, leveraging VDPA, create a vdpa device with virtio ID 7? I've already searched through the `drivers/vdpa/` directory, and I know that `vduse_dev.c` explicitly lists allowed device IDs: `VIRTIO_ID_BLOCK`, `VIRTIO_ID_NET`, and `VIRTIO_ID_FS`. And `vdpa_sim` only implements `vdpa_sim_net`, `vdpa_sim_blk`. So VDPA is a dead end as well. It's not the right approach. Okay, let's take a step back and check syzkaller. Does syzkaller have any descriptions, coverage, or bug reports related to `rpmsg`? Also, could it be testing rpmsg functionality through ioctls? I should search for tests related to `RPMSG_CREATE_EPT_IOCTL` or `RPMSG_SET_INCOMING_FLOWCONTROL` or even just a simple search for `rpmsg` in the `/tools/testing/selftests` and `samples/` directories. Time to broaden the search.
74/2	2026/10/26 11:49	tool	grepper	0m Args: { "Expression": "RPMSG_", "PathPrefixes": [ "samples/", "tools/testing/selftests/" ] } Results: { "Output": "samples/Kconfig=113=config SAMPLE_QMI_CLIENT\n--\nsamples/Kconfig-122-\nsamples/Kconfig:123:config SAMPLE_RPMSG_CLIENT\nsamples/Kconfig-124-\ttristate \"Build rpmsg client sample -- loadable modules only\"\n--\nsamples/Makefile=20=obj-$(CONFIG_SAMPLE_QMI_CLIENT)\t\t+= qmi/\nsamples/Makefile:21:obj-$(CONFIG_SAMPLE_RPMSG_CLIENT)\t+= rpmsg/\nsamples/Makefile-22-subdir-$(CONFIG_SAMPLE_SECCOMP)\t\t+= seccomp\n--\nsamples/rpmsg/Makefile-1-# SPDX-License-Identifier: GPL-2.0-only\nsamples/rpmsg/Makefile:2:obj-$(CONFIG_SAMPLE_RPMSG_CLIENT) += rpmsg_client_sample.o\n" }
75/2	2026/10/26 11:49	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 65478 output: 39 thoughts: 44 Thoughts: Okay, let's see. My first instinct is to check the usual suspects, the `tools/testing/selftests` directory, looking for anything related to rpmsg. Hmm, no matches there. That's unexpected. Alright, let's pivot. What about the sample code directory? Specifically, `samples/rpmsg/rpmsg_client_sample.c`. That's a likely candidate for demonstrating rpmsg usage. Time to investigate!
76/2	2026/10/26 11:49	tool	read-file	0m Args: { "File": "samples/rpmsg/rpmsg_client_sample.c", "FirstLine": 1, "LineCount": 50 } Results: { "Contents": " 1:\t// SPDX-License-Identifier: GPL-2.0-only\n 2:\t/\n 3:\t Remote processor messaging - sample client driver\n 4:\t \n 5:\t Copyright (C) 2011 Texas Instruments, Inc.\n 6:\t * Copyright (C) 2011 Google, Inc.\n 7:\t \n 8:\t Ohad Ben-Cohen \u003cohad@wizery.com\u003e\n 9:\t * Brian Swetland \u003cswetland@google.com\u003e\n 10:\t /\n 11:\t\n 12:\t#include \u003clinux/kernel.h\u003e\n 13:\t#include \u003clinux/module.h\u003e\n 14:\t#include \u003clinux/rpmsg.h\u003e\n 15:\t\n 16:\t#define MSG\t\t\"hello world!\"\n 17:\t\n 18:\tstatic int count = 100;\n 19:\tmodule_param(count, int, 0644);\n 20:\t\n 21:\tstruct instance_data {\n 22:\t\tint rx_count;\n 23:\t};\n 24:\t\n 25:\tstatic int rpmsg_sample_cb(struct rpmsg_device rpdev, void data, int len,\n 26:\t\t\t\t\t\t\tvoid priv, u32 src)\n 27:\t{\n 28:\t\tint ret;\n 29:\t\tstruct instance_data idata = dev_get_drvdata(\u0026rpdev-\u003edev);\n 30:\t\n 31:\t\tdev_info(\u0026rpdev-\u003edev, \"incoming msg %d (src: 0x%x)\\n\",\n 32:\t\t\t ++idata-\u003erx_count, src);\n 33:\t\n 34:\t\tprint_hex_dump_debug(__func__, DUMP_PREFIX_NONE, 16, 1, data, len,\n 35:\t\t\t\t true);\n 36:\t\n 37:\t\t/ samples should not live forever /\n 38:\t\tif (idata-\u003erx_count \u003e= count) {\n 39:\t\t\tdev_info(\u0026rpdev-\u003edev, \"goodbye!\\n\");\n 40:\t\t\treturn 0;\n 41:\t\t}\n 42:\t\n 43:\t\t/ send a new message now */\n 44:\t\tret = rpmsg_send(rpdev-\u003eept, MSG, strlen(MSG));\n 45:\t\tif (ret)\n 46:\t\t\tdev_err(\u0026rpdev-\u003edev, \"rpmsg_send failed: %d\\n\", ret);\n 47:\t\n 48:\t\treturn 0;\n 49:\t}\n 50:\t\n" }
77/2	2026/10/26 11:49	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 66332 output: 37 thoughts: 20 Thoughts: Okay, here's the summary, tailored for an expert audience, in the first person, reflecting the described thought process: Diving into the RPMSG Header Hmm, before I start writing, I need to make sure I'm not reinventing the wheel or missing something obvious in the Linux kernel's RPMSG implementation. Let's see... Wait! That's it! Let me go check the include file! `include/uapi/linux/rpmsg.h`. That's where all the definitions, structures, and constants related to the RPMSG subsystem should be. I need to refresh my memory on the current API and data structures there. Gotta ensure this new approach aligns with the existing kernel infrastructure. I'll make sure there are no surprises and account for any existing mechanisms.
78/2	2026/10/26 11:49	tool	read-file	0m Args: { "File": "include/uapi/linux/rpmsg.h", "FirstLine": 1, "LineCount": 50 } Results: { "Contents": " 1:\t/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note /\n 2:\t/\n 3:\t * Copyright (c) 2016, Linaro Ltd.\n 4:\t /\n 5:\t\n 6:\t#ifndef _UAPI_RPMSG_H_\n 7:\t#define _UAPI_RPMSG_H_\n 8:\t\n 9:\t#include \u003clinux/ioctl.h\u003e\n 10:\t#include \u003clinux/types.h\u003e\n 11:\t\n 12:\t#define RPMSG_ADDR_ANY\t\t0xFFFFFFFF\n 13:\t\n 14:\t/\n 15:\t struct rpmsg_endpoint_info - endpoint info representation\n 16:\t * @name: name of service\n 17:\t * @src: local address. To set to RPMSG_ADDR_ANY if not used.\n 18:\t * @dst: destination address. To set to RPMSG_ADDR_ANY if not used.\n 19:\t /\n 20:\tstruct rpmsg_endpoint_info {\n 21:\t\tchar name[32];\n 22:\t\t__u32 src;\n 23:\t\t__u32 dst;\n 24:\t};\n 25:\t\n 26:\t/\n 27:\t Instantiate a new rmpsg char device endpoint.\n 28:\t /\n 29:\t#define RPMSG_CREATE_EPT_IOCTL\t_IOW(0xb5, 0x1, struct rpmsg_endpoint_info)\n 30:\t\n 31:\t/\n 32:\t Destroy a rpmsg char device endpoint created by the RPMSG_CREATE_EPT_IOCTL.\n 33:\t /\n 34:\t#define RPMSG_DESTROY_EPT_IOCTL\t_IO(0xb5, 0x2)\n 35:\t\n 36:\t/\n 37:\t Instantiate a new local rpmsg service device.\n 38:\t /\n 39:\t#define RPMSG_CREATE_DEV_IOCTL\t_IOW(0xb5, 0x3, struct rpmsg_endpoint_info)\n 40:\t\n 41:\t/\n 42:\t Release a local rpmsg device.\n 43:\t /\n 44:\t#define RPMSG_RELEASE_DEV_IOCTL\t_IOW(0xb5, 0x4, struct rpmsg_endpoint_info)\n 45:\t\n 46:\t/\n 47:\t Get the flow control state of the remote rpmsg char device.\n 48:\t */\n 49:\t#define RPMSG_GET_OUTGOING_FLOWCONTROL _IOR(0xb5, 0x5, int)\n 50:\t\n" }
79/2	2026/10/26 11:49	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 67262 output: 38 thoughts: 25 Thoughts: Okay, let's dive into this. Here's my take on those lines: Analyzing `include/uapi/linux/rpmsg.h`, Lines 51-60 Alright, time to get my head back into this RPMSG kernel stuff. I'm going to zero in on lines 51 through 60 of `include/uapi/linux/rpmsg.h`. Immediately, I'm expecting to see some core definitions relating to the RPMSG framework – probably data structures or constants that are fundamental to how messages are exchanged. I'll be looking for any hints about message formats, channel identifiers, endpoint registrations, or maybe even error codes. This section is likely the foundation for higher-level API calls and data structures I'm working with, so understanding this piece is crucial. It's time to see what this block of code is revealing about the protocol's inner workings. Let's see what gems are hidden in there.
80/2	2026/10/26 11:49	tool	read-file	0m Args: { "File": "include/uapi/linux/rpmsg.h", "FirstLine": 51, "LineCount": 20 } Results: { "Contents": " 51:\t/*\n 52:\t Set the flow control state of the local rpmsg char device.\n 53:\t */\n 54:\t#define RPMSG_SET_INCOMING_FLOWCONTROL _IOR(0xb5, 0x6, int)\n 55:\t\n 56:\t#endif\n" }
81/2	2026/10/26 11:49	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 67623 output: 39 thoughts: 652 Thoughts: Analyzing the RPMSG Flow Control Patch Okay, so this patch, `ef9f789b3f5fe7743026f0349064fb807a2de3c9`, is modifying the `RPMSG_SET_INCOMING_FLOWCONTROL` ioctl within `rpmsg_char.c`. That's the key. I need to understand the change. The diff shows a mutex is now being used around the `rpmsg_set_flow_control` call within `rpmsg_eptdev_ioctl`. That makes sense; looks like they're trying to add some thread safety. The original code was likely vulnerable to concurrent access. This change looks like a definite improvement, at least from this snippet. Now, wait a second. I want to understand the context of this ioctl. When was `RPMSG_SET_INCOMING_FLOWCONTROL` even introduced? I'm going to scan the code for the definition of the `RPMSG_SET_INCOMING_FLOWCONTROL` case within `rpmsg_eptdev_ioctl` to get an idea of when it was added, and to make sure I am fully familiar with the wider functionality. Furthermore, how is this `rpmsg_eptdev_ioctl` actually reached? I need to understand the path from userspace down to the ioctl call, which means tracing the open path. I need to figure out how a user interacts with the `eptdev` file, since that file descriptor is passed to this ioctl. I'll need to read `rpmsg_eptdev_open` in `rpmsg_char.c` (roughly lines 100-250) to understand how these devices are opened and what capabilities are exposed. This will give me a better understanding of how the new mutex affects overall system behavior and the potential implications of the flow control changes. Understanding the complete call chain helps me understand if the locking is sufficient.
82/2	2026/10/26 11:49	tool	read-file	0m Args: { "File": "drivers/rpmsg/rpmsg_char.c", "FirstLine": 100, "LineCount": 80 } Results: { "Contents": " 100:\t\tput_device(\u0026eptdev-\u003edev);\n 101:\t\n 102:\t\treturn 0;\n 103:\t}\n 104:\tEXPORT_SYMBOL(rpmsg_chrdev_eptdev_destroy);\n 105:\t\n 106:\tstatic int rpmsg_ept_cb(struct rpmsg_device rpdev, void buf, int len,\n 107:\t\t\t\tvoid priv, u32 addr)\n 108:\t{\n 109:\t\tstruct rpmsg_eptdev eptdev = priv;\n 110:\t\tstruct sk_buff skb;\n 111:\t\n 112:\t\tif (!eptdev)\n 113:\t\t\treturn 0;\n 114:\t\n 115:\t\tskb = alloc_skb(len, GFP_ATOMIC);\n 116:\t\tif (!skb)\n 117:\t\t\treturn -ENOMEM;\n 118:\t\n 119:\t\tskb_put_data(skb, buf, len);\n 120:\t\n 121:\t\tspin_lock(\u0026eptdev-\u003equeue_lock);\n 122:\t\tskb_queue_tail(\u0026eptdev-\u003equeue, skb);\n 123:\t\tspin_unlock(\u0026eptdev-\u003equeue_lock);\n 124:\t\n 125:\t\t/ wake up any blocking processes, waiting for new data /\n 126:\t\twake_up_interruptible(\u0026eptdev-\u003ereadq);\n 127:\t\n 128:\t\treturn 0;\n 129:\t}\n 130:\t\n 131:\tstatic int rpmsg_ept_flow_cb(struct rpmsg_device rpdev, void priv, bool enable)\n 132:\t{\n 133:\t\tstruct rpmsg_eptdev eptdev = priv;\n 134:\t\n 135:\t\tif (!eptdev)\n 136:\t\t\treturn 0;\n 137:\t\n 138:\t\teptdev-\u003eremote_flow_restricted = enable;\n 139:\t\teptdev-\u003eremote_flow_updated = true;\n 140:\t\n 141:\t\twake_up_interruptible(\u0026eptdev-\u003ereadq);\n 142:\t\n 143:\t\treturn 0;\n 144:\t}\n 145:\t\n 146:\tstatic int rpmsg_eptdev_open(struct inode inode, struct file filp)\n 147:\t{\n 148:\t\tstruct rpmsg_eptdev eptdev = cdev_to_eptdev(inode-\u003ei_cdev);\n 149:\t\tstruct rpmsg_endpoint ept;\n 150:\t\tstruct rpmsg_device rpdev = eptdev-\u003erpdev;\n 151:\t\tstruct device dev = \u0026eptdev-\u003edev;\n 152:\t\n 153:\t\tmutex_lock(\u0026eptdev-\u003eept_lock);\n 154:\t\tif (eptdev-\u003eept) {\n 155:\t\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n 156:\t\t\treturn -EBUSY;\n 157:\t\t}\n 158:\t\n 159:\t\tif (!eptdev-\u003erpdev) {\n 160:\t\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n 161:\t\t\treturn -ENETRESET;\n 162:\t\t}\n 163:\t\n 164:\t\tget_device(dev);\n 165:\t\n 166:\t\t/\n 167:\t\t If the default_ept is set, the rpmsg device default endpoint is used.\n 168:\t\t * Else a new endpoint is created on open that will be destroyed on release.\n 169:\t\t */\n 170:\t\tif (eptdev-\u003edefault_ept)\n 171:\t\t\tept = eptdev-\u003edefault_ept;\n 172:\t\telse\n 173:\t\t\tept = rpmsg_create_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev-\u003echinfo);\n 174:\t\n 175:\t\tif (!ept) {\n 176:\t\t\tdev_err(dev, \"failed to open %s\\n\", eptdev-\u003echinfo.name);\n 177:\t\t\tput_device(dev);\n 178:\t\t\tmutex_unlock(\u0026eptdev-\u003eept_lock);\n 179:\t\t\treturn -EINVAL;\n" }
83/2	2026/10/26 11:49	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 69894 output: 20 thoughts: 684 Thoughts: RPMSG Device Creation Deep Dive Okay, so I'm diving into how `/dev/rpmsgX` devices are created. First, `rpmsg_eptdev_open` is the key – that's what gets called when a process tries to open one of these devices. But, and this is the important question: can `/dev/rpmsg0` even exist without the underlying hardware? I need to trace this back. Alright, looking at `rpmsg_char.c`, I see `rpmsg_chrdev_eptdev_add`. This looks promising; it calls `cdev_device_add` which is critical for making a character device available. Now, when is `rpmsg_chrdev_eptdev_add` called? Only twice: in `rpmsg_chrdev_probe` and `rpmsg_chrdev_eptdev_create`. Critically, both of those require a `struct rpmsg_device rpdev`. So, where do those* come from? That has to be `rpmsg_register_device()`. So, where in the entire kernel is that being called? Let's trace it down. First up, `drivers/rpmsg/mtk_rpmsg.c`. `mtk_rpmsg_register_device` is being called from `mtk_register_device_work_function`, which is part of the MediaTek SCP driver. Okay, that's an ARM SoC coprocessor setup. Next, `drivers/rpmsg/qcom_glink_native.c`, where `qcom_glink_rx_open` and `qcom_glink_create_chrdev` are in play. That's for the Qualcomm GLINK, which is on Snapdragon SoCs. Then, `drivers/rpmsg/qcom_smd.c` provides `qcom_smd_create_device` and `qcom_smd_create_chrdev`. SMD is another Qualcomm interface, also on Snapdragon. Finally, `drivers/rpmsg/virtio_rpmsg_bus.c` shows `__rpmsg_create_channel` and `rpmsg_virtio_add_ctrl_dev`. Ah, this is interesting. It's called during `rpmsg_probe`, which specifically probes for virtio devices with `VIRTIO_ID_RPMSG`. So, who's creating those virtio devices? I need to find all instances of `register_virtio_device` in the kernel. Let's start grepping...
84/2	2026/10/26 11:49	tool	grepper	0m Args: { "Expression": "register_virtio_device" } Results: { "Output": "Documentation/driver-api/virtio/virtio.rst=96=device is registered to the virtio bus::\n--\nDocumentation/driver-api/virtio/virtio.rst-119-\nDocumentation/driver-api/virtio/virtio.rst:120:\t\trc = register_virtio_device(\u0026vp_dev-\u003evdev);\nDocumentation/driver-api/virtio/virtio.rst-121-\n--\narch/um/drivers/virtio_uml.c=1218=static int virtio_uml_probe(struct platform_device pdev)\n--\narch/um/drivers/virtio_uml.c-1262-\narch/um/drivers/virtio_uml.c:1263:\trc = register_virtio_device(\u0026vu_dev-\u003evdev);\narch/um/drivers/virtio_uml.c-1264-\tif (rc) {\n--\narch/um/drivers/virtio_uml.c=1278=static void virtio_uml_remove(struct platform_device pdev)\n--\narch/um/drivers/virtio_uml.c-1281-\narch/um/drivers/virtio_uml.c:1282:\tunregister_virtio_device(\u0026vu_dev-\u003evdev);\narch/um/drivers/virtio_uml.c-1283-}\n--\ndrivers/platform/mellanox/mlxbf-tmfifo.c=1204=static int mlxbf_tmfifo_create_vdev(struct device dev,\n--\ndrivers/platform/mellanox/mlxbf-tmfifo.c-1248-\t/ Register the virtio device. /\ndrivers/platform/mellanox/mlxbf-tmfifo.c:1249:\tret = register_virtio_device(\u0026tm_vdev-\u003evdev);\ndrivers/platform/mellanox/mlxbf-tmfifo.c-1250-\treg_dev = tm_vdev;\ndrivers/platform/mellanox/mlxbf-tmfifo.c-1251-\tif (ret) {\ndrivers/platform/mellanox/mlxbf-tmfifo.c:1252:\t\tdev_err(dev, \"register_virtio_device failed\\n\");\ndrivers/platform/mellanox/mlxbf-tmfifo.c-1253-\t\tgoto vdev_fail;\n--\ndrivers/platform/mellanox/mlxbf-tmfifo.c=1272=static int mlxbf_tmfifo_delete_vdev(struct mlxbf_tmfifo fifo, int vdev_id)\n--\ndrivers/platform/mellanox/mlxbf-tmfifo.c-1280-\tif (tm_vdev) {\ndrivers/platform/mellanox/mlxbf-tmfifo.c:1281:\t\tunregister_virtio_device(\u0026tm_vdev-\u003evdev);\ndrivers/platform/mellanox/mlxbf-tmfifo.c-1282-\t\tmlxbf_tmfifo_free_vrings(fifo, tm_vdev);\n--\ndrivers/remoteproc/remoteproc_virtio.c=393=static int rproc_add_virtio_dev(struct rproc_vdev rvdev, int id)\n--\ndrivers/remoteproc/remoteproc_virtio.c-468-\ndrivers/remoteproc/remoteproc_virtio.c:469:\tret = register_virtio_device(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-470-\tif (ret) {\n--\ndrivers/remoteproc/remoteproc_virtio.c=491=static int rproc_remove_virtio_dev(struct device dev, void data)\n--\ndrivers/remoteproc/remoteproc_virtio.c-494-\ndrivers/remoteproc/remoteproc_virtio.c:495:\tunregister_virtio_device(vdev);\ndrivers/remoteproc/remoteproc_virtio.c-496-\treturn 0;\n--\ndrivers/s390/virtio/virtio_ccw.c=1285=static void virtio_ccw_remove(struct ccw_device cdev)\n--\ndrivers/s390/virtio/virtio_ccw.c-1292-\t\t\tvirtio_break_device(\u0026vcdev-\u003evdev);\ndrivers/s390/virtio/virtio_ccw.c:1293:\t\tunregister_virtio_device(\u0026vcdev-\u003evdev);\ndrivers/s390/virtio/virtio_ccw.c-1294-\t\tspin_lock_irqsave(get_ccwdev_lock(cdev), flags);\n--\ndrivers/s390/virtio/virtio_ccw.c=1301=static int virtio_ccw_offline(struct ccw_device cdev)\n--\ndrivers/s390/virtio/virtio_ccw.c-1309-\t\tvirtio_break_device(\u0026vcdev-\u003evdev);\ndrivers/s390/virtio/virtio_ccw.c:1310:\tunregister_virtio_device(\u0026vcdev-\u003evdev);\ndrivers/s390/virtio/virtio_ccw.c-1311-\tspin_lock_irqsave(get_ccwdev_lock(cdev), flags);\n--\ndrivers/s390/virtio/virtio_ccw.c=1363=static int virtio_ccw_online(struct ccw_device cdev)\n--\ndrivers/s390/virtio/virtio_ccw.c-1405-\ndrivers/s390/virtio/virtio_ccw.c:1406:\tret = register_virtio_device(\u0026vcdev-\u003evdev);\ndrivers/s390/virtio/virtio_ccw.c-1407-\tif (ret) {\n--\ndrivers/virtio/virtio.c=490=static int virtio_device_of_init(struct virtio_device dev)\n--\ndrivers/virtio/virtio.c-532-/\ndrivers/virtio/virtio.c:533: register_virtio_device - register virtio device\ndrivers/virtio/virtio.c-534- * @dev : virtio device to be registered\n--\ndrivers/virtio/virtio.c-540- /\ndrivers/virtio/virtio.c:541:int register_virtio_device(struct virtio_device dev)\ndrivers/virtio/virtio.c-542-{\n--\ndrivers/virtio/virtio.c-596-}\ndrivers/virtio/virtio.c:597:EXPORT_SYMBOL_GPL(register_virtio_device);\ndrivers/virtio/virtio.c-598-\n--\ndrivers/virtio/virtio.c=603=EXPORT_SYMBOL_GPL(is_virtio_device);\ndrivers/virtio/virtio.c-604-\ndrivers/virtio/virtio.c:605:void unregister_virtio_device(struct virtio_device dev)\ndrivers/virtio/virtio.c-606-{\n--\ndrivers/virtio/virtio.c-612-}\ndrivers/virtio/virtio.c:613:EXPORT_SYMBOL_GPL(unregister_virtio_device);\ndrivers/virtio/virtio.c-614-\n--\ndrivers/virtio/virtio_mmio.c=589=static int virtio_mmio_probe(struct platform_device pdev)\n--\ndrivers/virtio/virtio_mmio.c-658-\ndrivers/virtio/virtio_mmio.c:659:\trc = register_virtio_device(\u0026vm_dev-\u003evdev);\ndrivers/virtio/virtio_mmio.c-660-\tif (rc)\n--\ndrivers/virtio/virtio_mmio.c=670=static void virtio_mmio_remove(struct platform_device pdev)\n--\ndrivers/virtio/virtio_mmio.c-672-\tstruct virtio_mmio_device vm_dev = platform_get_drvdata(pdev);\ndrivers/virtio/virtio_mmio.c:673:\tunregister_virtio_device(\u0026vm_dev-\u003evdev);\ndrivers/virtio/virtio_mmio.c-674-}\n--\ndrivers/virtio/virtio_pci_common.c=683=static int virtio_pci_probe(struct pci_dev pci_dev,\n--\ndrivers/virtio/virtio_pci_common.c-723-\ndrivers/virtio/virtio_pci_common.c:724:\trc = register_virtio_device(\u0026vp_dev-\u003evdev);\ndrivers/virtio/virtio_pci_common.c-725-\treg_dev = vp_dev;\n--\ndrivers/virtio/virtio_pci_common.c=746=static void virtio_pci_remove(struct pci_dev pci_dev)\n--\ndrivers/virtio/virtio_pci_common.c-759-\ndrivers/virtio/virtio_pci_common.c:760:\tunregister_virtio_device(\u0026vp_dev-\u003evdev);\ndrivers/virtio/virtio_pci_common.c-761-\n--\ndrivers/virtio/virtio_vdpa.c=481=static int virtio_vdpa_probe(struct vdpa_device vdpa)\n--\ndrivers/virtio/virtio_vdpa.c-507-\tvd_dev-\u003evdev.id.vendor = ops-\u003eget_vendor_id(vdpa);\ndrivers/virtio/virtio_vdpa.c:508:\tret = register_virtio_device(\u0026vd_dev-\u003evdev);\ndrivers/virtio/virtio_vdpa.c-509-\treg_dev = vd_dev;\n--\ndrivers/virtio/virtio_vdpa.c=527=static void virtio_vdpa_remove(struct vdpa_device vdpa)\n--\ndrivers/virtio/virtio_vdpa.c-530-\ndrivers/virtio/virtio_vdpa.c:531:\tunregister_virtio_device(\u0026vd_dev-\u003evdev);\ndrivers/virtio/virtio_vdpa.c-532-}\n--\ninclude/linux/virtio.h=195=void virtio_add_status(struct virtio_device dev, unsigned int status);\ninclude/linux/virtio.h:196:int register_virtio_device(struct virtio_device dev);\ninclude/linux/virtio.h:197:void unregister_virtio_device(struct virtio_device dev);\ninclude/linux/virtio.h-198-bool is_virtio_device(struct device dev);\n" }
85/2	2026/10/26 11:49	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 73933 output: 27 thoughts: 1381 Thoughts: Analyzing Potential RPMSG Virtio Device Instantiation Okay, so I'm trying to figure out if I can get a Virtio RPMSG device up and running, specifically on amd64 in a QEMU environment. First, I need to understand where `register_virtio_device` is called from. I see it's used in several places: `virtio_uml.c` (that's User-Mode Linux, so probably not relevant here), `mlxbf-tmfifo.c` (Mellanox, which likely means specific hardware), `remoteproc_virtio.c` (remoteproc framework, interesting), `virtio_ccw.c` (s390, unlikely), `virtio_mmio.c` (Virtio MMIO, potential), `virtio_pci_common.c` (Virtio PCI, another possibility), and `virtio_vdpa.c` (Virtio vDPA, worth investigating). My immediate thought is, can any of these register an RPMSG device on amd64 in QEMU? Let's zoom in on `remoteproc` first. Can any remoteproc driver even run on amd64? I need to check the Kconfig for each remoteproc driver. Okay, here's what I've got from `drivers/remoteproc/Kconfig`: all of these drivers are architecture-specific! They depend on things like ARCH_ZYNQMP, ARCH_MXC, ARCH_MEDIATEK, ARCH_OMAP4, SOC_AM33XX, ARCH_DAVINCI_DA850, ARCH_KEYSTONE, ARCH_MESON, TI_PRUSS, ARCH_QCOM, ARCH_RENESAS, ARCH_STI, ARCH_STM32, ARCH_K3 or COMPILE_TEST. All of them are platform drivers! And all of them use Device Tree (OF) matching. So even if I compile a remoteproc driver with `COMPILE_TEST` on x86, it will never probe unless there's an OF device tree node for it. And standard amd64 QEMU (PC or Q35 machine type, ACPI-based) doesn't have an OF device tree. There are no DT nodes for these SoCs. That rules out remoteproc, it seems. Alright, let's go back to the other options: `virtio_pci` and `virtio_mmio`. In a standard amd64 QEMU setup, does QEMU even have a Virtio RPMSG device to attach? No. QEMU does not offer a virtio-rpmsg device. Then, can a virtio device be created dynamically at runtime? Let's dig into `virtio_vdpa`. Does `virtio_vdpa` allow creating a device with `VIRTIO_ID_RPMSG`? Looking again in `drivers/vdpa/`, vDPA has `vdpa_mgmtdev_register`. Management devices can create vDPA devices via netlink (`vdpa dev add`). Which management devices exist? Let's see: `vdpa_sim_net` (NET), `vdpa_sim_blk` (BLOCK), `ifcvf` (NET or BLOCK), `mlx5_vnet` (NET), `pds_vdpa` (NET), `octep_vdpa` (NET or CRYPTO), `eni_vdpa` (NET), and `vduse` (BLOCK, NET, FS). Nope, none of these support RPMSG. Wait a second… what about USB? Could a USB gadget possibly create an rpmsg device? I'll grep the `drivers/usb/` directory.
86/2	2026/10/26 11:50	tool	grepper	0m Error: no matches Args: { "Expression": "rpmsg", "PathPrefixes": [ "drivers/usb/" ] } Results: { "error": "no matches" }
87/2	2026/10/26 11:50	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 76175 output: 29 thoughts: 201 Thoughts: Okay, let me think this through. Investigating Potential RPMSG Loopback/Dummy Drivers Alright, so the initial search in `drivers/usb/` turned up nothing useful. Hmm, what about `drivers/rpmsg/`? That seems like a more logical place to look for something virtual or loopback-related. The question is, does such a thing even exist? Let's check. Okay, let's start by quickly scanning the files in `drivers/rpmsg/`. I see: `mtk_rpmsg.c`, `qcom_glink_native.c`, `qcom_glink_rpm.c`, `qcom_glink_smem.c`, `qcom_glink_ssr.c`, `qcom_smd.c`, `rpmsg_char.c`, `rpmsg_core.c`, `rpmsg_ctrl.c`, `rpmsg_ns.c`, and `virtio_rpmsg_bus.c`. I need to look for any test or mock implementations. It's possible it's called something else that hints at a testing use. Alright, that's step one. Now, let's broaden that to anywhere in the `drivers/` directory, just to make sure I don't miss anything that's categorized differently. I know how Linux kernel developers like to organize things! It could be in a more generic "testing" subdirectory, or even something seemingly unrelated. I need to be thorough.
88/2	2026/10/26 11:50	tool	grepper	0m Error: no matches Args: { "Expression": "rpmsg.loopback\|rpmsg.test\|rpmsg.dummy" } Results:* { "error": "no matches" }
89/2	2026/10/26 11:50	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 76743 output: 36 thoughts: 35 Thoughts: Here's my thought process, summarized as you requested: Investigating Potential RPMSG Driver Locations Okay, first things first. Before I dive too deep, I need to get a handle on where the Remote Processor Messaging (RPMSG) driver might reside within the kernel source tree. My initial instinct is to check the most likely areas, so I need to search the source code for the term `rpmsg`. My preferred approach is to check common driver locations, so I should start with the `drivers/platform/` directory. This is a common home for drivers that are platform-specific and handle communication with hardware. Then, since RPMSG is a method of inter-processor communication, I need to check the kernel level implementations themselves, so the `kernel/` directory is the next logical target. Finally, given that I'm likely to find hardware-specific implementations, I'll also want to look in `arch/x86/` to see if there are any architecture-specific RPMSG components. I need to be thorough and cover these areas to ensure that I don't overlook anything obvious.
90/2	2026/10/26 11:50	tool	grepper	0m Args: { "Expression": "rpmsg", "PathPrefixes": [ "arch/x86/", "drivers/platform/" ] } Results: { "Output": "\nFull output is too long, showing 200 out of 207 lines.\nUse more precise expression or PathPrefixes if possible.\n\nNumber of matching lines per file (3 files in total):\ndrivers/platform/chrome/Kconfig:3\ndrivers/platform/chrome/Makefile:1\ndrivers/platform/chrome/cros_ec_rpmsg.c:74\n\ndrivers/platform/chrome/Kconfig=98=config CROS_EC_RPMSG\ndrivers/platform/chrome/Kconfig:99:\ttristate \"ChromeOS Embedded Controller (rpmsg)\"\ndrivers/platform/chrome/Kconfig-100-\tdepends on CROS_EC \u0026\u0026 RPMSG \u0026\u0026 OF\n--\ndrivers/platform/chrome/Kconfig-102-\t If you say Y here, you get support for talking to the ChromeOS EC\ndrivers/platform/chrome/Kconfig:103:\t through rpmsg. This uses a simple byte-level protocol with a\ndrivers/platform/chrome/Kconfig-104-\t checksum. Also since there's no addition EC-to-host interrupt, this\n--\ndrivers/platform/chrome/Kconfig-107-\t To compile this driver as a module, choose M here: the\ndrivers/platform/chrome/Kconfig:108:\t module will be called cros_ec_rpmsg.\ndrivers/platform/chrome/Kconfig-109-\n--\ndrivers/platform/chrome/Makefile=16=obj-$(CONFIG_CROS_TYPEC_SWITCH)\t\t+= cros_typec_switch.o\ndrivers/platform/chrome/Makefile:17:obj-$(CONFIG_CROS_EC_RPMSG)\t\t+= cros_ec_rpmsg.o\ndrivers/platform/chrome/Makefile-18-obj-$(CONFIG_CROS_EC_SPI)\t\t+= cros_ec_spi.o\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-12-#include \u003clinux/platform_device.h\u003e\ndrivers/platform/chrome/cros_ec_rpmsg.c:13:#include \u003clinux/rpmsg.h\u003e\ndrivers/platform/chrome/cros_ec_rpmsg.c-14-#include \u003clinux/slab.h\u003e\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-22-/*\ndrivers/platform/chrome/cros_ec_rpmsg.c:23: struct cros_ec_rpmsg_response - rpmsg message format from EC.\ndrivers/platform/chrome/cros_ec_rpmsg.c-24- \n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-29- /\ndrivers/platform/chrome/cros_ec_rpmsg.c:30:struct cros_ec_rpmsg_response {\ndrivers/platform/chrome/cros_ec_rpmsg.c-31-\tu8 type;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-35-/*\ndrivers/platform/chrome/cros_ec_rpmsg.c:36: struct cros_ec_rpmsg - information about a EC over rpmsg.\ndrivers/platform/chrome/cros_ec_rpmsg.c-37- \ndrivers/platform/chrome/cros_ec_rpmsg.c:38: @rpdev:\trpmsg device we are connected to\ndrivers/platform/chrome/cros_ec_rpmsg.c-39- * @xfer_ack:\tcompletion for host command transfer.\ndrivers/platform/chrome/cros_ec_rpmsg.c-40- * @host_event_work:\tWork struct for pending host event.\ndrivers/platform/chrome/cros_ec_rpmsg.c:41: * @ept: The rpmsg endpoint of this channel.\ndrivers/platform/chrome/cros_ec_rpmsg.c-42- * @has_pending_host_event: Boolean used to check if there is a pending event.\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-44- /\ndrivers/platform/chrome/cros_ec_rpmsg.c:45:struct cros_ec_rpmsg {\ndrivers/platform/chrome/cros_ec_rpmsg.c:46:\tstruct rpmsg_device rpdev;\ndrivers/platform/chrome/cros_ec_rpmsg.c-47-\tstruct completion xfer_ack;\ndrivers/platform/chrome/cros_ec_rpmsg.c-48-\tstruct work_struct host_event_work;\ndrivers/platform/chrome/cros_ec_rpmsg.c:49:\tstruct rpmsg_endpoint ept;\ndrivers/platform/chrome/cros_ec_rpmsg.c-50-\tbool has_pending_host_event;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-54-/\ndrivers/platform/chrome/cros_ec_rpmsg.c:55: cros_ec_cmd_xfer_rpmsg - Transfer a message over rpmsg and receive the reply\ndrivers/platform/chrome/cros_ec_rpmsg.c-56- \n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-64- /\ndrivers/platform/chrome/cros_ec_rpmsg.c:65:static int cros_ec_cmd_xfer_rpmsg(struct cros_ec_device ec_dev,\ndrivers/platform/chrome/cros_ec_rpmsg.c-66-\t\t\t\t struct cros_ec_command ec_msg)\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-71-/*\ndrivers/platform/chrome/cros_ec_rpmsg.c:72: cros_ec_pkt_xfer_rpmsg - Transfer a packet over rpmsg and receive the reply\ndrivers/platform/chrome/cros_ec_rpmsg.c-73- \n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-78- /\ndrivers/platform/chrome/cros_ec_rpmsg.c:79:static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device ec_dev,\ndrivers/platform/chrome/cros_ec_rpmsg.c-80-\t\t\t\t struct cros_ec_command ec_msg)\ndrivers/platform/chrome/cros_ec_rpmsg.c-81-{\ndrivers/platform/chrome/cros_ec_rpmsg.c:82:\tstruct cros_ec_rpmsg ec_rpmsg = ec_dev-\u003epriv;\ndrivers/platform/chrome/cros_ec_rpmsg.c-83-\tstruct ec_host_response response;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-95-\ndrivers/platform/chrome/cros_ec_rpmsg.c:96:\treinit_completion(\u0026ec_rpmsg-\u003exfer_ack);\ndrivers/platform/chrome/cros_ec_rpmsg.c:97:\tret = rpmsg_send(ec_rpmsg-\u003eept, ec_dev-\u003edout, len);\ndrivers/platform/chrome/cros_ec_rpmsg.c-98-\tif (ret) {\ndrivers/platform/chrome/cros_ec_rpmsg.c:99:\t\tdev_err(ec_dev-\u003edev, \"rpmsg send failed\\n\");\ndrivers/platform/chrome/cros_ec_rpmsg.c-100-\t\treturn ret;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-103-\ttimeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);\ndrivers/platform/chrome/cros_ec_rpmsg.c:104:\tret = wait_for_completion_timeout(\u0026ec_rpmsg-\u003exfer_ack, timeout);\ndrivers/platform/chrome/cros_ec_rpmsg.c-105-\tif (!ret) {\ndrivers/platform/chrome/cros_ec_rpmsg.c:106:\t\tdev_err(ec_dev-\u003edev, \"rpmsg send timeout\\n\");\ndrivers/platform/chrome/cros_ec_rpmsg.c-107-\t\treturn -EIO;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c=148=static void\ndrivers/platform/chrome/cros_ec_rpmsg.c:149:cros_ec_rpmsg_host_event_function(struct work_struct host_event_work)\ndrivers/platform/chrome/cros_ec_rpmsg.c-150-{\ndrivers/platform/chrome/cros_ec_rpmsg.c:151:\tstruct cros_ec_rpmsg ec_rpmsg = container_of(host_event_work,\ndrivers/platform/chrome/cros_ec_rpmsg.c:152:\t\t\t\t\t\t struct cros_ec_rpmsg,\ndrivers/platform/chrome/cros_ec_rpmsg.c-153-\t\t\t\t\t\t host_event_work);\ndrivers/platform/chrome/cros_ec_rpmsg.c-154-\ndrivers/platform/chrome/cros_ec_rpmsg.c:155:\tcros_ec_irq_thread(0, dev_get_drvdata(\u0026ec_rpmsg-\u003erpdev-\u003edev));\ndrivers/platform/chrome/cros_ec_rpmsg.c-156-}\ndrivers/platform/chrome/cros_ec_rpmsg.c-157-\ndrivers/platform/chrome/cros_ec_rpmsg.c:158:static int cros_ec_rpmsg_callback(struct rpmsg_device rpdev, void data,\ndrivers/platform/chrome/cros_ec_rpmsg.c-159-\t\t\t\t int len, void priv, u32 src)\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-161-\tstruct cros_ec_device ec_dev = dev_get_drvdata(\u0026rpdev-\u003edev);\ndrivers/platform/chrome/cros_ec_rpmsg.c:162:\tstruct cros_ec_rpmsg ec_rpmsg = ec_dev-\u003epriv;\ndrivers/platform/chrome/cros_ec_rpmsg.c:163:\tstruct cros_ec_rpmsg_response resp;\ndrivers/platform/chrome/cros_ec_rpmsg.c-164-\ndrivers/platform/chrome/cros_ec_rpmsg.c-165-\tif (!len) {\ndrivers/platform/chrome/cros_ec_rpmsg.c:166:\t\tdev_warn(ec_dev-\u003edev, \"rpmsg received empty response\");\ndrivers/platform/chrome/cros_ec_rpmsg.c-167-\t\treturn -EINVAL;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-170-\tresp = data;\ndrivers/platform/chrome/cros_ec_rpmsg.c:171:\tlen -= offsetof(struct cros_ec_rpmsg_response, data);\ndrivers/platform/chrome/cros_ec_rpmsg.c-172-\tif (resp-\u003etype == HOST_COMMAND_MARK) {\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-180-\t\tmemcpy(ec_dev-\u003edin, resp-\u003edata, len);\ndrivers/platform/chrome/cros_ec_rpmsg.c:181:\t\tcomplete(\u0026ec_rpmsg-\u003exfer_ack);\ndrivers/platform/chrome/cros_ec_rpmsg.c-182-\t} else if (resp-\u003etype == HOST_EVENT_MARK) {\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-186-\t\t /\ndrivers/platform/chrome/cros_ec_rpmsg.c:187:\t\tif (ec_rpmsg-\u003eprobe_done)\ndrivers/platform/chrome/cros_ec_rpmsg.c:188:\t\t\tschedule_work(\u0026ec_rpmsg-\u003ehost_event_work);\ndrivers/platform/chrome/cros_ec_rpmsg.c-189-\t\telse\ndrivers/platform/chrome/cros_ec_rpmsg.c:190:\t\t\tec_rpmsg-\u003ehas_pending_host_event = true;\ndrivers/platform/chrome/cros_ec_rpmsg.c-191-\t} else {\ndrivers/platform/chrome/cros_ec_rpmsg.c:192:\t\tdev_warn(ec_dev-\u003edev, \"rpmsg received invalid type = %d\",\ndrivers/platform/chrome/cros_ec_rpmsg.c-193-\t\t\t resp-\u003etype);\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-199-\ndrivers/platform/chrome/cros_ec_rpmsg.c:200:static struct rpmsg_endpoint \ndrivers/platform/chrome/cros_ec_rpmsg.c:201:cros_ec_rpmsg_create_ept(struct rpmsg_device rpdev)\ndrivers/platform/chrome/cros_ec_rpmsg.c-202-{\ndrivers/platform/chrome/cros_ec_rpmsg.c:203:\tstruct rpmsg_channel_info chinfo = {};\ndrivers/platform/chrome/cros_ec_rpmsg.c-204-\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-208-\ndrivers/platform/chrome/cros_ec_rpmsg.c:209:\treturn rpmsg_create_ept(rpdev, cros_ec_rpmsg_callback, NULL, chinfo);\ndrivers/platform/chrome/cros_ec_rpmsg.c-210-}\ndrivers/platform/chrome/cros_ec_rpmsg.c-211-\ndrivers/platform/chrome/cros_ec_rpmsg.c:212:static int cros_ec_rpmsg_probe(struct rpmsg_device rpdev)\ndrivers/platform/chrome/cros_ec_rpmsg.c-213-{\ndrivers/platform/chrome/cros_ec_rpmsg.c-214-\tstruct device dev = \u0026rpdev-\u003edev;\ndrivers/platform/chrome/cros_ec_rpmsg.c:215:\tstruct cros_ec_rpmsg ec_rpmsg;\ndrivers/platform/chrome/cros_ec_rpmsg.c-216-\tstruct cros_ec_device ec_dev;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-222-\ndrivers/platform/chrome/cros_ec_rpmsg.c:223:\tec_rpmsg = devm_kzalloc(dev, sizeof(ec_rpmsg), GFP_KERNEL);\ndrivers/platform/chrome/cros_ec_rpmsg.c:224:\tif (!ec_rpmsg)\ndrivers/platform/chrome/cros_ec_rpmsg.c-225-\t\treturn -ENOMEM;\ndrivers/platform/chrome/cros_ec_rpmsg.c-226-\ndrivers/platform/chrome/cros_ec_rpmsg.c:227:\tec_dev-\u003epriv = ec_rpmsg;\ndrivers/platform/chrome/cros_ec_rpmsg.c:228:\tec_dev-\u003ecmd_xfer = cros_ec_cmd_xfer_rpmsg;\ndrivers/platform/chrome/cros_ec_rpmsg.c:229:\tec_dev-\u003epkt_xfer = cros_ec_pkt_xfer_rpmsg;\ndrivers/platform/chrome/cros_ec_rpmsg.c-230-\tec_dev-\u003ephys_name = dev_name(\u0026rpdev-\u003edev);\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-232-\ndrivers/platform/chrome/cros_ec_rpmsg.c:233:\tec_rpmsg-\u003erpdev = rpdev;\ndrivers/platform/chrome/cros_ec_rpmsg.c:234:\tinit_completion(\u0026ec_rpmsg-\u003exfer_ack);\ndrivers/platform/chrome/cros_ec_rpmsg.c:235:\tINIT_WORK(\u0026ec_rpmsg-\u003ehost_event_work,\ndrivers/platform/chrome/cros_ec_rpmsg.c:236:\t\t cros_ec_rpmsg_host_event_function);\ndrivers/platform/chrome/cros_ec_rpmsg.c-237-\ndrivers/platform/chrome/cros_ec_rpmsg.c:238:\tec_rpmsg-\u003eept = cros_ec_rpmsg_create_ept(rpdev);\ndrivers/platform/chrome/cros_ec_rpmsg.c:239:\tif (!ec_rpmsg-\u003eept)\ndrivers/platform/chrome/cros_ec_rpmsg.c-240-\t\treturn -ENOMEM;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-243-\tif (ret \u003c 0) {\ndrivers/platform/chrome/cros_ec_rpmsg.c:244:\t\trpmsg_destroy_ept(ec_rpmsg-\u003eept);\ndrivers/platform/chrome/cros_ec_rpmsg.c:245:\t\tcancel_work_sync(\u0026ec_rpmsg-\u003ehost_event_work);\ndrivers/platform/chrome/cros_ec_rpmsg.c-246-\t\treturn ret;\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-248-\ndrivers/platform/chrome/cros_ec_rpmsg.c:249:\tec_rpmsg-\u003eprobe_done = true;\ndrivers/platform/chrome/cros_ec_rpmsg.c-250-\ndrivers/platform/chrome/cros_ec_rpmsg.c:251:\tif (ec_rpmsg-\u003ehas_pending_host_event)\ndrivers/platform/chrome/cros_ec_rpmsg.c:252:\t\tschedule_work(\u0026ec_rpmsg-\u003ehost_event_work);\ndrivers/platform/chrome/cros_ec_rpmsg.c-253-\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-256-\ndrivers/platform/chrome/cros_ec_rpmsg.c:257:static void cros_ec_rpmsg_remove(struct rpmsg_device rpdev)\ndrivers/platform/chrome/cros_ec_rpmsg.c-258-{\ndrivers/platform/chrome/cros_ec_rpmsg.c-259-\tstruct cros_ec_device ec_dev = dev_get_drvdata(\u0026rpdev-\u003edev);\ndrivers/platform/chrome/cros_ec_rpmsg.c:260:\tstruct cros_ec_rpmsg ec_rpmsg = ec_dev-\u003epriv;\ndrivers/platform/chrome/cros_ec_rpmsg.c-261-\ndrivers/platform/chrome/cros_ec_rpmsg.c-262-\tcros_ec_unregister(ec_dev);\ndrivers/platform/chrome/cros_ec_rpmsg.c:263:\trpmsg_destroy_ept(ec_rpmsg-\u003eept);\ndrivers/platform/chrome/cros_ec_rpmsg.c:264:\tcancel_work_sync(\u0026ec_rpmsg-\u003ehost_event_work);\ndrivers/platform/chrome/cros_ec_rpmsg.c-265-}\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-267-#ifdef CONFIG_PM_SLEEP\ndrivers/platform/chrome/cros_ec_rpmsg.c:268:static int cros_ec_rpmsg_suspend(struct device dev)\ndrivers/platform/chrome/cros_ec_rpmsg.c-269-{\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-274-\ndrivers/platform/chrome/cros_ec_rpmsg.c:275:static int cros_ec_rpmsg_resume(struct device *dev)\ndrivers/platform/chrome/cros_ec_rpmsg.c-276-{\n--\ndrivers/platform/chrome/cros_ec_rpmsg.c-282-\ndrivers/platform/chrome/cros_ec_rpmsg.c:283:static SIMPLE_DEV_PM_OPS(cros_ec_rpmsg_pm_ops, cros_ec_rpmsg_suspend,\ndrivers/platform/chrome/cros_ec_rpmsg.c:284:\t\t\t cros_ec_rpmsg_resume);\ndrivers/platform/chrome/cros_ec_rpmsg.c-285-\ndrivers/platform/chrome/cros_ec_rpmsg.c:286:static const struct of_device_id cros_ec_rpmsg_of_match[] = {\ndrivers/platform/chrome/cros_ec_rpmsg.c:287:\t{ .compatible = \"google,cros-ec-rpmsg\", },\ndrivers/platform/chrome/cros_ec_rpmsg.c-288-\t{ }\ndrivers/platform/chrome/cros_ec_rpmsg.c-289-};\ndrivers/platform/chrome/cros_ec_rpmsg.c:290:MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);\ndrivers/platform/chrome/cros_ec_rpmsg.c-291-\ndrivers/platform/chrome/cros_ec_rpmsg.c:292:static struct rpmsg_driver cros_ec_driver_rpmsg = {\ndrivers/platform/chrome/cros_ec_rpmsg.c-293-\t.drv = {\ndrivers/platform/chrome/cros_ec_rpmsg.c:294:\t\t.name = \"cros-ec-rpmsg\",\ndrivers/platform/chrome/cros_ec_rpmsg.c:295:\t\t.of_match_table = cros_ec_rpmsg_of_match,\ndrivers/platform/chrome/cros_ec_rpmsg.c:296:\t\t.pm\t= \u0026cros_ec_rpmsg_pm_ops,\ndrivers/platform/chrome/cros_ec_rpmsg.c-297-\t},\ndrivers/platform/chrome/cros_ec_rpmsg.c:298:\t.probe\t\t= cros_ec_rpmsg_probe,\n\n" }
91/2	2026/10/26 11:50	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 82500 output: 31 thoughts: 1458 Thoughts: Analyzing RPMsg in QEMU/KVM: A Deep Dive into Device Creation and ioctls Okay, let's break this down systematically. I see this `cros_ec_rpmsg` driver – it's a client for the RPMsg bus, matching on "google,cros-ec-rpmsg". It's dependent on `CROS_EC`, `RPMSG`, and `OF`. But the real question is, can we ever get an RPMsg device going in a standard amd64 QEMU/KVM virtual machine? Let's trace it out. First, RPMsg is fundamentally designed for Asymmetric Multiprocessing architectures. It's for Linux talking to coprocessors or microcontrollers, think Cortex-M cores, DSPs, the works. The RPMsg bus requires an underlying hardware or bus driver. I know there are drivers for MediaTek SCP, Qualcomm GLINK/SMEM/SMD, and Virtio RPMsg. Now, Virtio RPMsg, that's interesting. It requires a virtio device with ID `VIRTIO_ID_RPMSG` (7). Where does this virtio RPMsg device come from? It's only created by `remoteproc` via `rproc_add_virtio_dev()`. And every single remoteproc driver in the kernel is geared towards embedded SoCs, like Qualcomm, TI, NXP, ST, Renesas, MediaTek, AMD MicroBlaze-V, Xilinx, Ingenic, and Amlogic. None of those are what QEMU is emulating! The standard QEMU for x86_64 emulates standard PC/Q35 hardware. It doesn't emulate these SoCs. There's no PCI virtio-rpmsg device in standard QEMU. And vDPA? Nope, no virtio-rpmsg support there either. So, no virtio-rpmsg device means no `rpmsg_device`. Without an `rpmsg_device`, neither `/dev/rpmsg_ctrlX` nor `/dev/rpmsgX` can exist. Looking at `rpmsg_char.c`, it registers the char major, but doesn't create the device nodes. Those `/dev/rpmsg%d` devices only get created when `rpmsg_chrdev_probe()` or `ioctl(RPMSG_CREATE_EPT_IOCTL)` are called. `/dev/rpmsg_ctrl%d` is only created by `rpmsg_ctrldev_probe()`. None of that happens without a valid `rpmsg_device`. So `/dev/rpmsg` and `/dev/rpmsg_ctrl` never show up, and that means I can't call `rpmsg_eptdev_ioctl` on amd64 in QEMU! That patch? It's a non-starter. Wait, hold on. Could someone manually `mknod /dev/rpmsg0` and get around this? I need to double-check. Okay, let's see, what happens if I run `mknod /dev/rpmsg0 c <major> 0` and open it. Let's dig into `drivers/rpmsg/rpmsg_char.c`. The `alloc_chrdev_region` function reserves the major:minor device numbers, but it doesn't actually register a `cdev`! Device addition happens within `rpmsg_chrdev_eptdev_add()`, which is where `cdev_init` and `cdev_device_add` are called. So, if `cdev_device_add` hasn't been called for that minor number, when user space does `open()` on `/dev/rpmsg0` (the manually created one), the VFS char dev open `chrdev_open()` looks up the `kobj_map` (via `cdev_map`). But since no `cdev` is registered at that major/minor, `chrdev_open()` is going to return `-ENXIO`. The driver's `rpmsg_eptdev_open` is never called, therefore if `open` fails, you can't do an `ioctl` on it! Hold on! Is there any other way to call `rpmsg_eptdev_ioctl`? Let me see... `rpmsg_eptdev_ioctl` is tied to `rpmsg_eptdev_fops`, and that's only used for `cdev_init` which is only added via `cdev_device_add` which, once again, happens when an `eptdev` is created. That only happens when we have a valid `rpmsg_
92/2	2026/10/26 11:50	tool	grepper	0m Error: no matches Args: { "Expression": "rpmsg", "PathPrefixes": [ "drivers/platform/x86/" ] } Results: { "error": "no matches" }
93/2	2026/10/26 11:50	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 85028 output: 25 thoughts: 242 Thoughts: RPMSG Device Creation Conundrum Okay, so I'm trying to figure out how rpmsg devices are actually created within the kernel, right? I started with the obvious: `drivers/platform/x86/`. Nope, nothing there of interest. Hold on... I vaguely recall something in `samples/`. Ah yes, that `samples/rpmsg/rpmsg_client_sample.c` file. Could that be it? Does that file instantiate the rpmsg device? Quick check... nope, it doesn't. It defines an `rpmsg_driver`, which is interesting. It binds to an `rpmsg_device`, but it doesn't create one. Here's that crucial piece: ```c static struct rpmsg_driver rpmsg_sample_client = { .drv.name = KBUILD_MODNAME, .id_table = rpmsg_driver_sample_id_table, .probe = rpmsg_sample_probe, .callback = rpmsg_sample_cb, .remove = rpmsg_sample_remove, }; module_rpmsg_driver(rpmsg_sample_client); ``` So, this driver relies on an existing rpmsg device already being present. That means I need to look deeper. Hmm, where else might it be? Let me consider likely areas. What about kernel tests? Perhaps in `tools/testing/` or the core kernel itself (`kernel/`) or possibly networking (`net/`)? Let's try `tools/` first and see if I can find something there using `grep`.
94/2	2026/10/26 11:50	tool	grepper	0m Error: no matches Args: { "Expression": "rpmsg", "PathPrefixes": [ "tools/" ] } Results: { "error": "no matches" }
95/2	2026/10/26 11:50	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 85674 output: 25 thoughts: 19 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, and written as if they were my own: Investigating the Missing RPMsg Implementation Right, let's see... I'm looking for the `rpmsg` implementation, specifically. Hmm, it's not where I'd expect it, under `tools/`. That's a little unusual, but not necessarily a showstopper. Okay, let's pivot. My first instinct, given the usual structure of these sorts of projects, is to check the `Documentation/` directory. That's the logical place to look for any architecture-level explanations, perhaps including pointers to where the core code actually resides. Time to see what the documentation holds... hopefully, there's a detailed overview, or at least a map that clarifies where things have been placed, instead of assuming. We'll find out!
96/2	2026/10/26 11:50	tool	grepper	0m Args: { "Expression": "rpmsg", "PathPrefixes": [ "Documentation/" ] } Results: { "Output": "\nFull output is too long, showing 200 out of 498 lines.\nUse more precise expression or PathPrefixes if possible.\n\nNumber of matching lines per file (15 files in total):\nDocumentation/ABI/testing/sysfs-bus-rpmsg:32\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:9\nDocumentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml:1\nDocumentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml:1\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:17\nDocumentation/devicetree/bindings/remoteproc/renesas,rcar-rproc.yaml:1\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml:2\nDocumentation/devicetree/bindings/remoteproc/ti,pru-rproc.yaml:1\nDocumentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml:1\nDocumentation/devicetree/bindings/sound/fsl,rpmsg.yaml:28\nDocumentation/staging/index.rst:1\nDocumentation/staging/remoteproc.rst:9\nDocumentation/staging/rpmsg.rst:65\nDocumentation/translations/zh_CN/staging/index.rst:1\nDocumentation/userspace-api/ioctl/ioctl-number.rst:1\n\nDocumentation/ABI/testing/sysfs-bus-rpmsg:1:What:\t\t/sys/bus/rpmsg/devices/.../name\nDocumentation/ABI/testing/sysfs-bus-rpmsg-2-Date:\t\tJune 2011\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg=5=Description:\nDocumentation/ABI/testing/sysfs-bus-rpmsg:6:\t\tEvery rpmsg device is a communication channel with a remote\nDocumentation/ABI/testing/sysfs-bus-rpmsg-7-\t\tprocessor. Channels are identified with a (textual) name,\nDocumentation/ABI/testing/sysfs-bus-rpmsg-8-\t\twhich is maximum 32 bytes long (defined as RPMSG_NAME_SIZE in\nDocumentation/ABI/testing/sysfs-bus-rpmsg:9:\t\trpmsg.h).\nDocumentation/ABI/testing/sysfs-bus-rpmsg-10-\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg-12-\nDocumentation/ABI/testing/sysfs-bus-rpmsg:13:What:\t\t/sys/bus/rpmsg/devices/.../src\nDocumentation/ABI/testing/sysfs-bus-rpmsg-14-Date:\t\tJune 2011\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg=17=Description:\nDocumentation/ABI/testing/sysfs-bus-rpmsg:18:\t\tEvery rpmsg device is a communication channel with a remote\nDocumentation/ABI/testing/sysfs-bus-rpmsg:19:\t\tprocessor. Channels have a local (\"source\") rpmsg address,\nDocumentation/ABI/testing/sysfs-bus-rpmsg:20:\t\tand remote (\"destination\") rpmsg address. When an entity\nDocumentation/ABI/testing/sysfs-bus-rpmsg-21-\t\tstarts listening on one end of a channel, it assigns it with\nDocumentation/ABI/testing/sysfs-bus-rpmsg:22:\t\ta unique rpmsg address (a 32 bits integer). This way when\nDocumentation/ABI/testing/sysfs-bus-rpmsg:23:\t\tinbound messages arrive to this address, the rpmsg core\nDocumentation/ABI/testing/sysfs-bus-rpmsg-24-\t\tdispatches them to the listening entity (a kernel driver).\nDocumentation/ABI/testing/sysfs-bus-rpmsg-25-\nDocumentation/ABI/testing/sysfs-bus-rpmsg:26:\t\tThis sysfs entry contains the src (local) rpmsg address\nDocumentation/ABI/testing/sysfs-bus-rpmsg-27-\t\tof this channel. If it contains 0xffffffff, then an address\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg-30-\nDocumentation/ABI/testing/sysfs-bus-rpmsg:31:What:\t\t/sys/bus/rpmsg/devices/.../dst\nDocumentation/ABI/testing/sysfs-bus-rpmsg-32-Date:\t\tJune 2011\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg=35=Description:\nDocumentation/ABI/testing/sysfs-bus-rpmsg:36:\t\tEvery rpmsg device is a communication channel with a remote\nDocumentation/ABI/testing/sysfs-bus-rpmsg:37:\t\tprocessor. Channels have a local (\"source\") rpmsg address,\nDocumentation/ABI/testing/sysfs-bus-rpmsg:38:\t\tand remote (\"destination\") rpmsg address. When an entity\nDocumentation/ABI/testing/sysfs-bus-rpmsg-39-\t\tstarts listening on one end of a channel, it assigns it with\nDocumentation/ABI/testing/sysfs-bus-rpmsg:40:\t\ta unique rpmsg address (a 32 bits integer). This way when\nDocumentation/ABI/testing/sysfs-bus-rpmsg:41:\t\tinbound messages arrive to this address, the rpmsg core\nDocumentation/ABI/testing/sysfs-bus-rpmsg-42-\t\tdispatches them to the listening entity.\nDocumentation/ABI/testing/sysfs-bus-rpmsg-43-\nDocumentation/ABI/testing/sysfs-bus-rpmsg:44:\t\tThis sysfs entry contains the dst (remote) rpmsg address\nDocumentation/ABI/testing/sysfs-bus-rpmsg-45-\t\tof this channel. If it contains 0xffffffff, then an address\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg-47-\t\tis attached to this channel is exposing a service to the\nDocumentation/ABI/testing/sysfs-bus-rpmsg:48:\t\tremote processor. This make it a local rpmsg server,\nDocumentation/ABI/testing/sysfs-bus-rpmsg-49-\t\tand it is listening for inbound messages that may be sent\nDocumentation/ABI/testing/sysfs-bus-rpmsg:50:\t\tfrom any remote rpmsg client; it is not bound to a single\nDocumentation/ABI/testing/sysfs-bus-rpmsg-51-\t\tremote entity).\nDocumentation/ABI/testing/sysfs-bus-rpmsg-52-\nDocumentation/ABI/testing/sysfs-bus-rpmsg:53:What:\t\t/sys/bus/rpmsg/devices/.../announce\nDocumentation/ABI/testing/sysfs-bus-rpmsg-54-Date:\t\tJune 2011\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg=57=Description:\nDocumentation/ABI/testing/sysfs-bus-rpmsg:58:\t\tEvery rpmsg device is a communication channel with a remote\nDocumentation/ABI/testing/sysfs-bus-rpmsg-59-\t\tprocessor. Channels are identified by a textual name (see\nDocumentation/ABI/testing/sysfs-bus-rpmsg:60:\t\t/sys/bus/rpmsg/devices/.../name above) and have a local\nDocumentation/ABI/testing/sysfs-bus-rpmsg:61:\t\t(\"source\") rpmsg address, and remote (\"destination\") rpmsg\nDocumentation/ABI/testing/sysfs-bus-rpmsg-62-\t\taddress.\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg-65-\t\tor remote, starts listening on it for messages (and is thus\nDocumentation/ABI/testing/sysfs-bus-rpmsg:66:\t\tcalled an rpmsg server).\nDocumentation/ABI/testing/sysfs-bus-rpmsg-67-\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg-76-\nDocumentation/ABI/testing/sysfs-bus-rpmsg:77:What:\t\t/sys/bus/rpmsg/devices/.../driver_override\nDocumentation/ABI/testing/sysfs-bus-rpmsg-78-Date:\t\tApril 2018\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg=81=Description:\nDocumentation/ABI/testing/sysfs-bus-rpmsg:82:\t\tEvery rpmsg device is a communication channel with a remote\nDocumentation/ABI/testing/sysfs-bus-rpmsg-83-\t\tprocessor. Channels are identified by a textual name (see\nDocumentation/ABI/testing/sysfs-bus-rpmsg:84:\t\t/sys/bus/rpmsg/devices/.../name above) and have a local\nDocumentation/ABI/testing/sysfs-bus-rpmsg:85:\t\t(\"source\") rpmsg address, and remote (\"destination\") rpmsg\nDocumentation/ABI/testing/sysfs-bus-rpmsg-86-\t\taddress.\n--\nDocumentation/ABI/testing/sysfs-bus-rpmsg-88-\t\tThe listening entity (or client) which communicates with a\nDocumentation/ABI/testing/sysfs-bus-rpmsg:89:\t\tremote processor is referred as rpmsg driver. The rpmsg device\nDocumentation/ABI/testing/sysfs-bus-rpmsg:90:\t\tand rpmsg driver are matched based on rpmsg device name and\nDocumentation/ABI/testing/sysfs-bus-rpmsg:91:\t\trpmsg driver ID table.\nDocumentation/ABI/testing/sysfs-bus-rpmsg-92-\nDocumentation/ABI/testing/sysfs-bus-rpmsg:93:\t\tThis sysfs entry allows the rpmsg driver for a rpmsg device\nDocumentation/ABI/testing/sysfs-bus-rpmsg-94-\t\tto be specified which will override standard OF, ID table\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml=19=properties:\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-34- For implementations of the EC connected through RPMSG.\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:35: const: google,cros-ec-rpmsg\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-36- - description:\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-61-\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:62: mediatek,rpmsg-name:\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-63- description:\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:64: Must be defined if the cros-ec is a rpmsg device for a Mediatek\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:65: ARM Cortex M4 Co-processor. Contains the name of the rpmsg\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:66: device. Used to match the subnode to the rpmsg device announced by\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-67- the SCP.\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml=169=allOf:\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-189- contains:\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:190: const: google,cros-ec-rpmsg\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-191- then:\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-192- properties:\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:193: mediatek,rpmsg-name: false\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-194-\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-200- enum:\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:201: - google,cros-ec-rpmsg\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-202- - google,cros-ec-uart\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml=245=examples:\n--\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-296- cros-ec {\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml:297: compatible = \"google,cros-ec-rpmsg\";\nDocumentation/devicetree/bindings/embedded-controller/google,cros-ec.yaml-298- };\n--\nDocumentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml=72=properties:\n--\nDocumentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml-96- The node of system control processor (SCP), using\nDocumentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml:97: the remoteproc \u0026 rpmsg framework.\nDocumentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml-98-\n--\nDocumentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml=15=properties:\n--\nDocumentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml-51- description:\nDocumentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml:52: This property is required only if the rpmsg/virtio functionality is used.\nDocumentation/devicetree/bindings/remoteproc/fsl,imx-rproc.yaml-53- List of \u003c\u0026phandle type channel\u003e - 1 channel for TX, 1 channel for RX, 1 channel for RXDB.\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml=16=properties:\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-59-\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:60: cros-ec-rpmsg:\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-61- $ref: /schemas/embedded-controller/google,cros-ec.yaml\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-62- description:\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:63: This subnode represents the rpmsg device. The properties\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-64- of this node are defined by the individual bindings for\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:65: the rpmsg devices.\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-66-\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-67- required:\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:68: - mediatek,rpmsg-name\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-69-\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml=83=patternProperties:\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-127-\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:128: cros-ec-rpmsg:\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-129- $ref: /schemas/embedded-controller/google,cros-ec.yaml\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-130- description:\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:131: This subnode represents the rpmsg device. The properties\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-132- of this node are defined by the individual bindings for\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:133: the rpmsg devices.\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-134-\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-135- required:\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:136: - mediatek,rpmsg-name\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-137-\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml=211=examples:\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-223-\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:224: cros-ec-rpmsg {\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:225: compatible = \"google,cros-ec-rpmsg\";\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:226: mediatek,rpmsg-name = \"cros-ec-rpmsg\";\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-227- };\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-245-\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:246: cros-ec-rpmsg {\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:247: compatible = \"google,cros-ec-rpmsg\";\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:248: mediatek,rpmsg-name = \"cros-ec-rpmsg\";\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-249- };\n--\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-256-\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:257: cros-ec-rpmsg {\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:258: compatible = \"google,cros-ec-rpmsg\";\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml:259: mediatek,rpmsg-name = \"cros-ec-rpmsg\";\nDocumentation/devicetree/bindings/remoteproc/mtk,scp.yaml-260- };\n--\nDocumentation/devicetree/bindings/remoteproc/renesas,rcar-rproc.yaml=18=properties:\n--\nDocumentation/devicetree/bindings/remoteproc/renesas,rcar-rproc.yaml-31- remoteproc device. This is variable and describes the memories shared with\nDocumentation/devicetree/bindings/remoteproc/renesas,rcar-rproc.yaml:32: the remote processor (e.g. remoteproc firmware and carveouts, rpmsg\nDocumentation/devicetree/bindings/remoteproc/renesas,rcar-rproc.yaml-33- vrings, ...).\n--\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml=17=properties:\n--\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml-64- description:\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml:65: This property is required only if the rpmsg/virtio functionality is used.\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml-66- items:\n--\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml-100- remoteproc device. This is variable and describes the memories shared with\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml:101: the remote processor (e.g. remoteproc firmware and carveouts, rpmsg\nDocumentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml-102- vrings, ...).\n--\nDocumentation/devicetree/bindings/remoteproc/ti,pru-rproc.yaml=34=properties:\n--\nDocumentation/devicetree/bindings/remoteproc/ti,pru-rproc.yaml-71- description:\nDocumentation/devicetree/bindings/remoteproc/ti,pru-rproc.yaml:72: Interrupt specifiers enable the virtio/rpmsg communication between MPU\nDocumentation/devicetree/bindings/remoteproc/ti,pru-rproc.yaml-73- and the PRU/RTU cores. For the values of the interrupt cells please refer\n--\nDocumentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml=62=patternProperties:\n--\nDocumentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml-119- remoteproc device. This is variable and describes the memories shared with\nDocumentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml:120: the remote processor (e.g. remoteproc firmware and carveouts, rpmsg\n\n" }
97/2	2026/10/26 11:50	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 91478 output: 34 thoughts: 69 Thoughts: Here's my take: My Initial Assessment of Device Tree Bindings Okay, so device tree bindings and how they're used are pretty much exclusively an embedded systems thing. Think TI PRU, Renesas R-Car, ST STM32, MediaTek SCP, Qualcomm, NXP i.MX, Xilinx ZynqMP – that's the ballpark. It's a key part of how we handle hardware description on these platforms. But, before I get too far down that rabbit hole... hold on a second. I should double check something. Let me see what's in `Documentation/staging/rpmsg.rst`. Just to be sure I'm not missing anything that might change that picture.
98/2	2026/10/26 11:50	tool	read-file	0m Args: { "File": "Documentation/staging/rpmsg.rst", "FirstLine": 1, "LineCount": 80 } Results: { "Contents": " 1:\t============================================\n 2:\tRemote Processor Messaging (rpmsg) Framework\n 3:\t============================================\n 4:\t\n 5:\t.. note::\n 6:\t\n 7:\t This document describes the rpmsg bus and how to write rpmsg drivers.\n 8:\t To learn how to add rpmsg support for new platforms, check out remoteproc.txt\n 9:\t (also a resident of Documentation/).\n 10:\t\n 11:\tIntroduction\n 12:\t============\n 13:\t\n 14:\tModern SoCs typically employ heterogeneous remote processor devices in\n 15:\tasymmetric multiprocessing (AMP) configurations, which may be running\n 16:\tdifferent instances of operating system, whether it's Linux or any other\n 17:\tflavor of real-time OS.\n 18:\t\n 19:\tOMAP4, for example, has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP.\n 20:\tTypically, the dual cortex-A9 is running Linux in a SMP configuration,\n 21:\tand each of the other three cores (two M3 cores and a DSP) is running\n 22:\tits own instance of RTOS in an AMP configuration.\n 23:\t\n 24:\tTypically AMP remote processors employ dedicated DSP codecs and multimedia\n 25:\thardware accelerators, and therefore are often used to offload CPU-intensive\n 26:\tmultimedia tasks from the main application processor.\n 27:\t\n 28:\tThese remote processors could also be used to control latency-sensitive\n 29:\tsensors, drive random hardware blocks, or just perform background tasks\n 30:\twhile the main CPU is idling.\n 31:\t\n 32:\tUsers of those remote processors can either be userland apps (e.g. multimedia\n 33:\tframeworks talking with remote OMX components) or kernel drivers (controlling\n 34:\thardware accessible only by the remote processor, reserving kernel-controlled\n 35:\tresources on behalf of the remote processor, etc..).\n 36:\t\n 37:\tRpmsg is a virtio-based messaging bus that allows kernel drivers to communicate\n 38:\twith remote processors available on the system. In turn, drivers could then\n 39:\texpose appropriate user space interfaces, if needed.\n 40:\t\n 41:\tWhen writing a driver that exposes rpmsg communication to userland, please\n 42:\tkeep in mind that remote processors might have direct access to the\n 43:\tsystem's physical memory and other sensitive hardware resources (e.g. on\n 44:\tOMAP4, remote cores and hardware accelerators may have direct access to the\n 45:\tphysical memory, gpio banks, dma controllers, i2c bus, gptimers, mailbox\n 46:\tdevices, hwspinlocks, etc..). Moreover, those remote processors might be\n 47:\trunning RTOS where every task can access the entire memory/devices exposed\n 48:\tto the processor. To minimize the risks of rogue (or buggy) userland code\n 49:\texploiting remote bugs, and by that taking over the system, it is often\n 50:\tdesired to limit userland to specific rpmsg channels (see definition below)\n 51:\tit can send messages on, and if possible, minimize how much control\n 52:\tit has over the content of the messages.\n 53:\t\n 54:\tEvery rpmsg device is a communication channel with a remote processor (thus\n 55:\trpmsg devices are called channels). Channels are identified by a textual name\n 56:\tand have a local (\"source\") rpmsg address, and remote (\"destination\") rpmsg\n 57:\taddress.\n 58:\t\n 59:\tWhen a driver starts listening on a channel, its rx callback is bound with\n 60:\ta unique rpmsg local address (a 32-bit integer). This way when inbound messages\n 61:\tarrive, the rpmsg core dispatches them to the appropriate driver according\n 62:\tto their destination address (this is done by invoking the driver's rx handler\n 63:\twith the payload of the inbound message).\n 64:\t\n 65:\t\n 66:\tUser API\n 67:\t========\n 68:\t\n 69:\t::\n 70:\t\n 71:\t int rpmsg_send(struct rpmsg_endpoint ept, void data, int len);\n 72:\t\n 73:\tsends a message across to the remote processor from the given endpoint.\n 74:\tThe caller should specify the endpoint, the data it wants to send,\n 75:\tand its length (in bytes). The message will be sent on the specified\n 76:\tendpoint's channel, i.e. its source and destination address fields will be\n 77:\trespectively set to the endpoint's src address and its parent channel\n 78:\tdst addresses.\n 79:\t\n 80:\tIn case there are no TX buffers available, the function will block until\n" }
99/2	2026/10/26 11:50	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 92970 output: 47 thoughts: 200 Thoughts: RPMsg on amd64: A Quick Rethink Okay, so RPMsg, as I understand it, is deeply rooted in these remote coprocessor setups, primarily those found in embedded SoCs like OMAP, i.MX, Qualcomm, and TI K3 – you know, the usual suspects. And, of course, these aren't native to the amd64 (x86_64) architecture when running QEMU. That's the baseline assumption. But, wait a minute... could someone, theoretically, build or even run remoteproc or virtio-rpmsg on amd64? It warrants a closer look. Let's verify this... Are there any remoteproc drivers that could, in principle, probe and function on amd64 within a standard QEMU environment, without requiring specific physical hardware? Time to check everything in the `drivers/remoteproc/` directory. Alright, let's start with a systematic examination. Let's look at `AMD_MBV_BRAM_REMOTEPROC`, "AMD MicroBlaze/V BRAM-based remoteproc support". Okay, it depends on `(ARCH_ZYNQMP \|\| COMPILE_TEST)`. This requires more examination. Let's dig into `drivers/remoteproc/amd_mbv_bram_rproc.c` and see what's actually going on in there. It feels like there could be a sliver of hope!
100/2	2026/10/26 11:51	tool	grepper	0m Args: { "Expression": "probe\|of_match_table", "PathPrefixes": [ "drivers/remoteproc/amd_mbv_bram_rproc.c" ] } Results: { "Output": "drivers/remoteproc/amd_mbv_bram_rproc.c=134=static const struct rproc_ops amd_bram_rproc_ops = {\n--\ndrivers/remoteproc/amd_mbv_bram_rproc.c-143-\ndrivers/remoteproc/amd_mbv_bram_rproc.c:144:static int amd_bram_rproc_probe(struct platform_device *pdev)\ndrivers/remoteproc/amd_mbv_bram_rproc.c-145-{\n--\ndrivers/remoteproc/amd_mbv_bram_rproc.c-153-\tif (ret \u003c 0 \u0026\u0026 ret != -EINVAL)\ndrivers/remoteproc/amd_mbv_bram_rproc.c:154:\t\treturn dev_err_probe(dev, ret,\ndrivers/remoteproc/amd_mbv_bram_rproc.c-155-\t\t\t\t \"failed to parse firmware-name property\\n\");\n--\ndrivers/remoteproc/amd_mbv_bram_rproc.c-167-\tif (IS_ERR(priv-\u003eclk))\ndrivers/remoteproc/amd_mbv_bram_rproc.c:168:\t\treturn dev_err_probe(dev, PTR_ERR(priv-\u003eclk),\ndrivers/remoteproc/amd_mbv_bram_rproc.c-169-\t\t\t\t \"failed to get clock\\n\");\n--\ndrivers/remoteproc/amd_mbv_bram_rproc.c-177-\tif (IS_ERR(priv-\u003ereset))\ndrivers/remoteproc/amd_mbv_bram_rproc.c:178:\t\treturn dev_err_probe(dev, PTR_ERR(priv-\u003ereset),\ndrivers/remoteproc/amd_mbv_bram_rproc.c-179-\t\t\t\t \"failed to get reset gpio\\n\");\n--\ndrivers/remoteproc/amd_mbv_bram_rproc.c-184-\tif (ret)\ndrivers/remoteproc/amd_mbv_bram_rproc.c:185:\t\treturn dev_err_probe(dev, ret, \"failed to set DMA mask\\n\");\ndrivers/remoteproc/amd_mbv_bram_rproc.c-186-\n--\ndrivers/remoteproc/amd_mbv_bram_rproc.c-190-\tif (ret)\ndrivers/remoteproc/amd_mbv_bram_rproc.c:191:\t\treturn dev_err_probe(dev, ret, \"failed to register rproc\\n\");\ndrivers/remoteproc/amd_mbv_bram_rproc.c-192-\n--\ndrivers/remoteproc/amd_mbv_bram_rproc.c=202=static struct platform_driver amd_bram_rproc_driver = {\ndrivers/remoteproc/amd_mbv_bram_rproc.c:203:\t.probe = amd_bram_rproc_probe,\ndrivers/remoteproc/amd_mbv_bram_rproc.c-204-\t.driver = {\ndrivers/remoteproc/amd_mbv_bram_rproc.c-205-\t\t.name = \"amd-bram-rproc\",\ndrivers/remoteproc/amd_mbv_bram_rproc.c:206:\t\t.of_match_table = amd_bram_rproc_of_match,\ndrivers/remoteproc/amd_mbv_bram_rproc.c-207-\t},\n" }
101/2	2026/10/26 11:51	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 94467 output: 28 thoughts: 1209 Thoughts: Unreachable Code Path Analysis: rpmsg_char.c on amd64 Okay, let's break this down. This code in `rpmsg_char.c` matches the `amd_bram_rproc_of_match` structure, meaning it uses device tree. My initial thought is to check against the negative criteria outlined in section 2 of the prompt. We need to determine if this code is reachable within a standard QEMU environment on amd64, our target architecture. Looking at section 1, "reachability is the primary gate," so even if the code adds assertions or complexity, if it's not reachable, we're not fuzzing it. The question is, can we trigger any of the `rpmsg_char` functionality, specifically opening `/dev/rpmsg` or `/dev/rpmsg_ctrl`, on amd64 in QEMU? Let's be methodical. Can QEMU emulate an rpmsg backend or frontend? No, it cannot. QEMU has no such support for x86. Rpmsg is specifically designed for heterogeneous SoCs, usually ARM-based with different cores. There's no hardware, virtual hardware, or emulation of RPMsg on amd64. Even if `CONFIG_RPMSG_CHAR` and `CONFIG_RPMSG` are enabled in the kernel, the module initialization doesn't create any character devices directly via `alloc_chrdev_region`. It only reserves numbers. The character device (`cdev`) and device nodes are added via `rpmsg_chrdev_eptdev_add()` which requires an `rpmsg_device` instance. So, even if we tried to create a device file in userspace with `mknod`, the kernel wouldn't find a corresponding `cdev` and therefore we'd get `-ENXIO`. Thus, neither `/dev/rpmsg` nor `/dev/rpmsg_ctrl` can be opened on amd64. `rpmsg_eptdev_ioctl` is completely unreachable on amd64. Let me double check by searching for "rpmsg" within the ACPI drivers, to rule out any indirect instantiation of an rpmsg device on amd64 via ACPI.
102/2	2026/10/26 11:51	tool	grepper	0m Error: no matches Args: { "Expression": "rpmsg", "PathPrefixes": [ "drivers/acpi/" ] } Results: { "error": "no matches" }
103/2	2026/10/26 11:51	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 96195 output: 34 thoughts: 32 Thoughts: Okay, here's my summary, presented as a stream of thought: ACPI vs. SoC: Where's the RPMSG? Alright, no RPMSG drivers are present in `drivers/acpi/`. That's not where I'd expect to find them in most cases, but it's always worth a quick check just to be sure. Now, where else could it be? Given the nature of RPMSG, and its frequent association with System-on-Chip (SoC) architectures, my next logical step is to look within `drivers/soc/`. I'll delve into the `drivers/soc/` directory and see what's there. Let's see if we get lucky.
104/2	2026/10/26 11:51	tool	grepper	0m Args: { "Expression": "register_rpmsg\|rpmsg_register", "PathPrefixes": [ "drivers/soc/" ] } Results: { "Output": "drivers/soc/qcom/apr.c=699=static int __init apr_init(void)\n--\ndrivers/soc/qcom/apr.c-704-\tif (!ret)\ndrivers/soc/qcom/apr.c:705:\t\tret = register_rpmsg_driver(\u0026packet_router_driver);\ndrivers/soc/qcom/apr.c-706-\telse\n--\ndrivers/soc/qcom/apr.c=712=static void __exit apr_exit(void)\n--\ndrivers/soc/qcom/apr.c-714-\tbus_unregister(\u0026aprbus);\ndrivers/soc/qcom/apr.c:715:\tunregister_rpmsg_driver(\u0026packet_router_driver);\ndrivers/soc/qcom/apr.c-716-}\n--\ndrivers/soc/qcom/pmic_glink.c=424=static int pmic_glink_init(void)\n--\ndrivers/soc/qcom/pmic_glink.c-431-\ndrivers/soc/qcom/pmic_glink.c:432:\tret = register_rpmsg_driver(\u0026pmic_glink_rpmsg_driver);\ndrivers/soc/qcom/pmic_glink.c-433-\tif (ret \u003c 0) {\n--\ndrivers/soc/qcom/pmic_glink.c=442=static void pmic_glink_exit(void)\ndrivers/soc/qcom/pmic_glink.c-443-{\ndrivers/soc/qcom/pmic_glink.c:444:\tunregister_rpmsg_driver(\u0026pmic_glink_rpmsg_driver);\ndrivers/soc/qcom/pmic_glink.c-445-\tplatform_driver_unregister(\u0026pmic_glink_driver);\n--\ndrivers/soc/qcom/smd-rpm.c=258=static int __init qcom_smd_rpm_init(void)\ndrivers/soc/qcom/smd-rpm.c-259-{\ndrivers/soc/qcom/smd-rpm.c:260:\treturn register_rpmsg_driver(\u0026qcom_smd_rpm_driver);\ndrivers/soc/qcom/smd-rpm.c-261-}\n--\ndrivers/soc/qcom/smd-rpm.c=264=static void __exit qcom_smd_rpm_exit(void)\ndrivers/soc/qcom/smd-rpm.c-265-{\ndrivers/soc/qcom/smd-rpm.c:266:\tunregister_rpmsg_driver(\u0026qcom_smd_rpm_driver);\ndrivers/soc/qcom/smd-rpm.c-267-}\n" }
105/2	2026/10/26 11:51	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 97105 output: 28 thoughts: 27 Thoughts: Okay, here's my summary, in the first person, as requested: Assessing the Landscape for x86 Support Right, so, the initial scan suggests we're dealing exclusively with Qualcomm ARM. My immediate concern is, "What about the broader picture? Is this really the whole story, or are we missing something crucial?" My experience tells me to never jump to conclusions based on an initial observation. My mind immediately jumps to the potentially relevant directories. Specifically, I need to check `drivers/firmware/`. This is where I would expect to find the lower level stuff that might be relevant to x86, even if it's not the primary focus. Time to dig in and see what treasures, or lack thereof, this directory holds.
106/2	2026/10/26 11:51	tool	grepper	0m Error: no matches Args: { "Expression": "rpmsg", "PathPrefixes": [ "drivers/firmware/" ] } Results: { "error": "no matches" }
107/2	2026/10/26 11:51	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 97336 output: 34 thoughts: 19 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Analyzing the Search Results Alright, so the initial search returned absolutely nothing. Zero hits. That's a clear indicator that my original query, whatever it was, was too broad, too specific, or perhaps just fundamentally flawed in its keyword selection. It's a useful negative result, though; I can learn from it. Now, the next logical step, at least based on my understanding of this system, is to drill down into a specific area. My intuition tells me that the "sound/soc/" directory might hold relevant information. Perhaps there's a configuration file in the sound/soc directory that can resolve this issue. That's where I need to focus my efforts. I'll need to check the files contained in this folder to confirm that there isn't an obvious solution.
108/2	2026/10/26 11:51	tool	grepper	0m Error: no matches Args: { "Expression": "register_rpmsg\|rpmsg_register", "PathPrefixes": [ "sound/soc/" ] } Results: { "error": "no matches" }
109/2	2026/10/26 11:51	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 97587 output: 208 thoughts: 635 Thoughts: My Analysis of `rpmsg_eptdev_ioctl()` Reachability on amd64 Okay, so I've looked into this, and I'm concluding that the code in `drivers/rpmsg/rpmsg_char.c`, specifically the `rpmsg_eptdev_ioctl()` function and the handling of `RPMSG_SET_INCOMING_FLOWCONTROL`, is not fuzzer-worthy. Here's why: Essentially, the RPMsg framework, and this character device interface, rely on an underlying RPMsg bus and device. That usually means hardware like you find on embedded systems – think Qualcomm GLINK/SMD, MediaTek SCP, or virtio-rpmsg devices with `remoteproc` on ARM, RISC-V, or MIPS SoCs. There is nothing like this on amd64. QEMU, the standard virtualized environment we're considering, doesn't emulate any RPMsg hardware. We can't have any `/dev/rpmsg_ctrl` or `/dev/rpmsg` devices. The instructions are crystal clear, especially Section 1, which states that fuzzer-able code has to be actually executable in standard virtualized environments. Section 2 confirms the structural unreachability. This code path is essentially inaccessible because we're missing the necessary underlying hardware support on the target architecture. So, according to the instructions, since the modified code is structurally unreachable on amd64 in a standard QEMU environment, it should not be fuzzed. Therefore: * `WorthFuzzing` is `false`. * `EnableConfigs` is empty. * `FocusSymbols` is empty. * The `Reasoning` is a clear and concise explanation of the structural unreachability issue on amd64. I've double-checked all the requirements and arguments, and everything aligns. I'm ready to call `set-results` now.
110/2	2026/10/26 11:51	tool	set-results	0m Args: { "EnableConfigs": [], "FocusSymbols": [], "Reasoning": "The patch modifies rpmsg_eptdev_ioctl() in drivers/rpmsg/rpmsg_char.c to hold eptdev-\u003eept_lock and check for NULL eptdev-\u003eept during RPMSG_SET_INCOMING_FLOWCONTROL ioctls. However, RPMsg (Remote Processor Messaging) devices are exclusively provided by remote coprocessor subsystems on embedded SoCs (such as Qualcomm GLINK/SMD, MediaTek SCP, or remoteproc virtio devices). On the target architecture (amd64), no RPMsg hardware or virtual devices exist or are emulated in standard QEMU/GCE environments. Because no underlying rpmsg_device can be registered, neither /dev/rpmsg_ctrl* nor /dev/rpmsg* character devices can be instantiated or opened, rendering rpmsg_eptdev_ioctl structurally unreachable.", "WorthFuzzing": false } Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "The patch modifies rpmsg_eptdev_ioctl() in drivers/rpmsg/rpmsg_char.c to hold eptdev-\u003eept_lock and check for NULL eptdev-\u003eept during RPMSG_SET_INCOMING_FLOWCONTROL ioctls. However, RPMsg (Remote Processor Messaging) devices are exclusively provided by remote coprocessor subsystems on embedded SoCs (such as Qualcomm GLINK/SMD, MediaTek SCP, or remoteproc virtio devices). On the target architecture (amd64), no RPMsg hardware or virtual devices exist or are emulated in standard QEMU/GCE environments. Because no underlying rpmsg_device can be registered, neither /dev/rpmsg_ctrl* nor /dev/rpmsg* character devices can be instantiated or opened, rendering rpmsg_eptdev_ioctl structurally unreachable.", "WorthFuzzing": false }
111/1	2026/10/26 11:51	action	If	0m Args: { "WorthFuzzing": false } Results: null

LLM Calls Summary:
Total Calls	Total Tokens	Avg Tokens	Total Duration (Seconds)	Avg Duration (Seconds)

Tool Calls Summary:
Total Calls	Total Duration (Seconds)	Avg Duration (Seconds)