Commit 914873bc authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-build-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 build updates from Ingo Molnar:
 "Add the CONFIG_X86_NATIVE_CPU=y build option to locally optimize the
  kernel build with '-march=native'"

* tag 'x86-build-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kbuild/64: Restrict clang versions that can use '-march=native'
  x86/kbuild/64: Test for the availability of the -mtune=native compiler flag
  x86/kbuild/64: Add the CONFIG_X86_NATIVE_CPU option to locally optimize the kernel with '-march=native'
parents 24244df0 ad9b8618

arch/x86/Kconfig.cpu

+24 −0
Original line number Diff line number Diff line
@@ -245,6 +245,30 @@ config MATOM 


endchoice



config CC_HAS_MARCH_NATIVE

	# This flag might not be available in cross-compilers:

	def_bool $(cc-option, -march=native)

	# LLVM 18 has an easily triggered internal compiler error in core

	# networking code with '-march=native' on certain systems:

	# https://github.com/llvm/llvm-project/issues/72026

	# LLVM 19 introduces an optimization that resolves some high stack

	# usage warnings that only appear wth '-march=native'.

	depends on CC_IS_GCC || CLANG_VERSION >= 190100



config X86_NATIVE_CPU

	bool "Build and optimize for local/native CPU"

	depends on X86_64

	depends on CC_HAS_MARCH_NATIVE

	help

	  Optimize for the current CPU used to compile the kernel.

	  Use this option if you intend to build the kernel for your

	  local machine.



	  Note that such a kernel might not work optimally on a

	  different x86 machine.



	  If unsure, say N.



config X86_GENERIC

	bool "Generic x86 support"

	depends on X86_32

arch/x86/Makefile

+5 −0
Original line number Diff line number Diff line
@@ -173,8 +173,13 @@ else 
	# Use -mskip-rax-setup if supported.

	KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)



ifdef CONFIG_X86_NATIVE_CPU

        KBUILD_CFLAGS += -march=native

        KBUILD_RUSTFLAGS += -Ctarget-cpu=native

else

        KBUILD_CFLAGS += -march=x86-64 -mtune=generic

        KBUILD_RUSTFLAGS += -Ctarget-cpu=x86-64 -Ztune-cpu=generic

endif



        KBUILD_CFLAGS += -mno-red-zone

        KBUILD_CFLAGS += -mcmodel=kernel