Re: [PATCH] perf: fix building error in x86_64 when dwarf unwind is on

[Wang Nan <wangnan0@huawei.com>]

On 2014/12/29 15:56, Namhyung Kim wrote:
> Hi Wang,
> 
> (Adding Arnaldo and Jiri to CC)
> 
> On Sat, Dec 27, 2014 at 09:26:11AM +0800, Wang Nan wrote:
>> When build with 'make ARCH=x86' and dwarf unwind is on, there is a
>> compiling error:
>>
>>    CC       /home/wn/perf/arch/x86/util/unwind-libdw.o
>>    CC       /home/wn/perf/arch/x86/tests/regs_load.o
>>  arch/x86/tests/regs_load.S: Assembler messages:
>>  arch/x86/tests/regs_load.S:65: Error: operand type mismatch for `push'
>>  arch/x86/tests/regs_load.S:72: Error: operand type mismatch for `pop'
>>  make[1]: *** [/home/wn/perf/arch/x86/tests/regs_load.o] Error 1
>>  make[1]: INTERNAL: Exiting with 25 jobserver tokens available; should be 24!
>>  make: *** [all] Error 2
>>  ...
>>
>> Which is caused by incorrectly undefine macro HAVE_ARCH_X86_64_SUPPORT.
>> 'config/Makefile.arch' tests __x86_64__ only when 'ARCH=x86_64'. However,
>> with 'ARCH=x86', the underlying compile may also be x86_64, which causes
>> mismatching.
> 
> Hmm.. how did you compile this?  I guess ARCH=x86 requires -m32 flag
> to the gcc, did you pass it (like via EXTRA_CFLAGS=-m32)?
> 
> I'm confused by 'underlying compile may also be x86_64' part..
> 

I hit this problem when building perf with Yocto (https://www.yoctoproject.org/), which
is a famous building system for embeded system.

When building kernel, we can simply use 'make ARCH=x86' and select 'CONFIG_64BIT'
in menuconfig to get a x86_64 kernel. As a result, there building framework
like Yocto doesn't ever consider 'x86_64' as a valid ARCH option. See:
https://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/meta/classes/kernel-arch.bbclass
Therefore, when building with such framework, it uses a x86_64 compiler and ARCH=x86.

> Thanks,
> Namhyung
> 
> 
>>
>> This patch fixes it by checking __x86_64__ in both case of
>> 'ARCH=x86_64' and 'ARCH=x86'.
>>
>> Signed-off-by: Wang Nan <wangnan0@huawei.com>
>> ---
>>  tools/perf/config/Makefile.arch | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/tools/perf/config/Makefile.arch b/tools/perf/config/Makefile.arch
>> index 851cd01..303a096 100644
>> --- a/tools/perf/config/Makefile.arch
>> +++ b/tools/perf/config/Makefile.arch
>> @@ -15,6 +15,8 @@ endif
>>  
>>  ifeq ($(ARCH),x86_64)
>>    override ARCH := x86
>> +endif
>> +ifeq ($(ARCH),x86)
>>    IS_X86_64 := 0
>>    ifeq (, $(findstring m32,$(CFLAGS)))
>>      IS_X86_64 := $(shell echo __x86_64__ | ${CC} -E -x c - | tail -n 1)
>> -- 
>> 1.8.4
>>
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