From: Gary Guo This config detects if Rust and Clang have matching LLVM major version. All IR or bitcode operations (e.g. LTO) rely on LLVM major version to be matching, otherwise it may generate errors, or worse, miscompile silently due to change of IR semantics. It's usually suggested to use the exact same LLVM version, but this can be difficult to guarantee. Rust's suggestion [1] is also major-version only, so I think this check is sufficient for the kernel. Link: https://doc.rust-lang.org/rustc/linker-plugin-lto.html [1] Reviewed-by: Andreas Hindborg Signed-off-by: Gary Guo Signed-off-by: Matthew Maurer Signed-off-by: Alice Ryhl --- init/Kconfig | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/init/Kconfig b/init/Kconfig index e95d43457851862afc8313389777e4dd9348c178..0e900d3d8be7874a33e0f44754a8d038e68d7e65 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -82,6 +82,21 @@ config RUSTC_LLVM_VERSION int default $(rustc-llvm-version) +config RUSTC_LLVM_MAJOR_VERSION + int + default $(shell,expr $(rustc-llvm-version) / 10000) + +config RUSTC_CLANG_LLVM_COMPATIBLE + bool + default y if CC_IS_CLANG && RUSTC_LLVM_MAJOR_VERSION = $(shell,expr $(cc-version) / 10000) + help + This indicates whether Rust and Clang use LLVM of the same major + version. + + Operations involving handling LLVM IR or bitcode (e.g. cross-language + LTO) requires the same LLVM major version to work properly. For best + compatibility it is recommended that the exact same LLVM is used. + config ARCH_HAS_CC_CAN_LINK bool -- 2.53.0.rc1.225.gd81095ad13-goog