From: Michael Ellerman <mpe@ellerman•id.au>
To: Nicholas Piggin <npiggin@gmail•com>,
Daniel Axtens <dja@axtens•net>,
linuxppc-dev@lists•ozlabs.org,
llvmlinux@lists•linuxfoundation.org
Subject: Re: [RFC PATCH 2/8] powerpc: check for support for -Wa, -m{power4, any}
Date: Fri, 19 Mar 2021 21:53:47 +1100 [thread overview]
Message-ID: <87ft0r8ldw.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <1616117194.vwe39qw3i4.astroid@bobo.none>
Nicholas Piggin <npiggin@gmail•com> writes:
> Excerpts from Daniel Axtens's message of February 25, 2021 1:10 pm:
>> 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 <dja@axtens•net>
>> ---
>> 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.
It uses $(CC) but it doesn't pass it $CFLAGS AFAIK. So it would use
whatever the compiler default is for -mcpu etc. I think.
> I assume it used to be useful for cross compiling when as was called
> directly but I'm not sure.
We still use it directly in vdso32/Makefile.
cheers
next prev parent reply other threads:[~2021-03-19 10:54 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 3:09 [RFC PATCH 0/8] WIP support for the LLVM integrated assembler Daniel Axtens
2021-02-25 3:09 ` [PATCH 1/8] powerpc/64s/exception: Clean up a missed SRR specifier Daniel Axtens
2021-02-25 3:10 ` [RFC PATCH 2/8] powerpc: check for support for -Wa,-m{power4,any} Daniel Axtens
2021-03-19 1:32 ` [RFC PATCH 2/8] powerpc: check for support for -Wa, -m{power4, any} Nicholas Piggin
2021-03-19 10:53 ` Michael Ellerman [this message]
2021-02-25 3:10 ` [RFC PATCH 3/8] powerpc/head-64: do less gas-specific stuff with sections Daniel Axtens
2021-03-19 1:35 ` Nicholas Piggin
2021-02-25 3:10 ` [RFC PATCH 4/8] powerpc/ppc_asm: use plain numbers for registers Daniel Axtens
2021-02-25 15:25 ` Segher Boessenkool
2021-02-26 0:12 ` Daniel Axtens
2021-03-19 1:39 ` Nicholas Piggin
2021-02-25 3:10 ` [RFC PATCH 5/8] poweprc/lib/quad: Provide macros for lq/stq Daniel Axtens
2021-02-25 15:44 ` Segher Boessenkool
2021-02-26 0:13 ` Daniel Axtens
2021-02-25 3:10 ` [RFC PATCH 6/8] powerpc/mm/book3s64/hash: drop pre 2.06 tlbiel for clang Daniel Axtens
2021-03-19 2:01 ` Nicholas Piggin
2021-03-22 16:49 ` Christophe Leroy
2021-03-22 18:11 ` Nicholas Piggin
2021-03-24 15:51 ` Segher Boessenkool
2021-03-24 21:07 ` Segher Boessenkool
2021-02-25 3:10 ` [RFC PATCH 7/8] powerpc/purgatory: drop .machine specifier Daniel Axtens
2021-02-25 15:58 ` Segher Boessenkool
2021-02-26 0:17 ` Daniel Axtens
2021-03-19 2:05 ` Nicholas Piggin
2021-03-19 10:59 ` Michael Ellerman
2021-02-25 3:10 ` [RFC PATCH 8/8] powerpc/64/asm: don't reassign labels Daniel Axtens
2021-02-25 16:08 ` Segher Boessenkool
2021-02-26 0:28 ` Daniel Axtens
2021-03-19 2:15 ` Nicholas Piggin
2021-03-14 10:01 ` [RFC PATCH 0/8] WIP support for the LLVM integrated assembler Michael Ellerman
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