Commit ad9b861
x86/kbuild/64: Restrict clang versions that can use '-march=native'
There are two issues that can appear when building with clang and
'-march=native'.
The first issue is a compiler crash in the ipv6 stack with clang-18,
such as when building allmodconfig. This was frequently reported on the
LLVM issue tracker:
# Link: https://github.com/llvm/llvm-project/issues?q=is%3Aissue%20ip6_rcv_core
Stack dump:
0. Program arguments: clang ... -march=native ... net/ipv6/ip6_input.c
1. <eof> parser at end of file
2. Code generation
3. Running pass 'Function Pass Manager' on module 'net/ipv6/ip6_input.c'.
4. Running pass 'X86 DAG->DAG Instruction Selection' on function '@ip6_rcv_core'
The second issue is certain -Wframe-larger-than warnings that appear
with clang versions prior to 19, which introduced an optimization that
produces much better code:
# Link: llvm/llvm-project@90ba330 [2]
clang-18:
drivers/media/pci/saa7164/saa7164-core.c:605:20: error: stack frame size (2392) exceeds limit (2048) in 'saa7164_irq' [-Werror,-Wframe-larger-than]
605 | static irqreturn_t saa7164_irq(int irq, void *dev_id)
| ^
clang-19:
drivers/media/pci/saa7164/saa7164-core.c:605:20: error: stack frame size (216) exceeds limit (128) in 'saa7164_irq' [-Werror,-Wframe-larger-than]
605 | static irqreturn_t saa7164_irq(int irq, void *dev_id)
| ^
Restrict the testing of the availability of '-march=native' to all
supported GCC versions and clang-19 and newer to avoid these known
resolved issues.
Fixes: 0480bc7e65dc ("x86/kbuild/64: Add the CONFIG_X86_NATIVE_CPU option to locally optimize the kernel with '-march=native'")
Signed-off-by: Nathan Chancellor <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Tor Vic <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/20250324-x86-march-native-clang-19-and-newer-v1-1-3a05ed32a89e@kernel.org1 parent 0141208 commit ad9b861
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