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Re: [Patch v2] x86/build: require only gcc use -maccumulate-outgoing-args

From hpa@zytor.com
Newsgroups linux.kernel
Subject Re: [Patch v2] x86/build: require only gcc use -maccumulate-outgoing-args
Date 2017-05-05 08:50 +0200
Message-ID <tDFdU-6v3-1@gated-at.bofh.it> (permalink)
References <tDus9-7Mu-15@gated-at.bofh.it> <tDBWG-4lL-5@gated-at.bofh.it> <tDEUy-6lR-3@gated-at.bofh.it>
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On May 4, 2017 11:23:33 PM PDT, Ingo Molnar <mingo@kernel.org> wrote:
>
>* Nick Desaulniers <nick.desaulniers@gmail.com> wrote:
>
>> Other compilers, like clang, treat unknown compiler flags as errors.
>> 
>> Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
>> ---
>>  arch/x86/Makefile | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
>> index 4430dd489620..12757a252e6b 100644
>> --- a/arch/x86/Makefile
>> +++ b/arch/x86/Makefile
>> @@ -179,7 +179,7 @@ ifdef CONFIG_JUMP_LABEL
>>  endif
>>  
>>  ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
>> -	KBUILD_CFLAGS += -maccumulate-outgoing-args
>> +	KBUILD_CFLAGS += $(if $(filter
>gcc,$(cc-name)),-maccumulate-outgoing-args)
>>  endif
>>  
>>  # Stackpointer is addressed different for 32 bit and 64 bit x86
>
>The justification Josh gave for this pattern should be put into a
>comment and into 
>the changelog as well.
>
>Thanks,
>
>	Ingo

However, I don't think Josh's explanation is correct.  I am pretty sure it is a performance issue, not a correctness issue, and besides, a version of gcc that old won't be able to compile the kernel for other reasons, as evidenced by the fact that noone has complained about this option being mandatory.
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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[PATCH] x86/build: don't add -maccumulate-outgoing-args w/o compiler support Nick Desaulniers <nick.desaulniers@gmail.com> - 2017-05-04 08:30 +0200
  Re: [PATCH] x86/build: don't add -maccumulate-outgoing-args w/o  compiler support Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-04 21:20 +0200
    [Patch v2] x86/build: require only gcc use -maccumulate-outgoing-args Nick Desaulniers <nick.desaulniers@gmail.com> - 2017-05-05 05:20 +0200
      Re: [Patch v2] x86/build: require only gcc use  -maccumulate-outgoing-args Ingo Molnar <mingo@kernel.org> - 2017-05-05 08:30 +0200
        Re: [Patch v2] x86/build: require only gcc use -maccumulate-outgoing-args hpa@zytor.com - 2017-05-05 08:50 +0200
          Re: [Patch v2] x86/build: require only gcc use  -maccumulate-outgoing-args Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-05 15:10 +0200
            [Patch v3] x86/build: don't add -maccumulate-outgoing-args w/o compiler support Nick Desaulniers <nick.desaulniers@gmail.com> - 2017-05-06 05:10 +0200
              Re: [Patch v3] x86/build: don't add -maccumulate-outgoing-args w/o  compiler support Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-08 05:30 +0200
                [Patch v4] x86/build: don't add -maccumulate-outgoing-args w/o compiler support Nick Desaulniers <nick.desaulniers@gmail.com> - 2017-05-09 05:40 +0200
                Re: [Patch v4] x86/build: don't add -maccumulate-outgoing-args w/o  compiler support Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-09 05:50 +0200
                [tip:x86/urgent] x86/build: Don't add -maccumulate-outgoing-args  w/o compiler support tip-bot for Nick Desaulniers <tipbot@zytor.com> - 2017-05-09 08:50 +0200

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