Re: [RFC PATCH 2/8] powerpc: check for support for -Wa, -m{power4, any}
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2021-03-19 01:33:10
Excerpts from Daniel Axtens's message of February 25, 2021 1:10 pm:
quoted hunk ↗ jump to hunk
LLVM's integrated assembler does not like either -Wa,-mpower4 or -Wa,-many. So just don't pass them if they're not supported. Signed-off-by: Daniel Axtens <redacted> --- arch/powerpc/Makefile | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index 08cf0eade56a..3e2c72d20bb8 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile@@ -252,7 +252,9 @@ cpu-as-$(CONFIG_E500) += -Wa,-me500 # When using '-many -mpower4' gas will first try and find a matching power4 # mnemonic and failing that it will allow any valid mnemonic that GAS knows # about. GCC will pass -many to GAS when assembling, clang does not. -cpu-as-$(CONFIG_PPC_BOOK3S_64) += -Wa,-mpower4 -Wa,-many +# LLVM IAS doesn't understand either flag: https://github.com/ClangBuiltLinux/linux/issues/675 +# but LLVM IAS only supports ISA >= 2.06 for Book3S 64 anyway... +cpu-as-$(CONFIG_PPC_BOOK3S_64) += $(call as-option,-Wa$(comma)-mpower4) $(call as-option,-Wa$(comma)-many) cpu-as-$(CONFIG_PPC_E500MC) += $(call as-option,-Wa$(comma)-me500mc) KBUILD_AFLAGS += $(cpu-as-y)
I'm wondering why we even have this now. Kbuild's "AS" command goes through the C compiler now with relevant options like -mcpu. I assume it used to be useful for cross compiling when as was called directly but I'm not sure. Thanks, Nick