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Re: [PATCH] x86-64: Don't set GLRO(dl_platform) to NULL [BZ #22299]


On Wed, Dec 13, 2017 at 12:48 AM, Aurelien Jarno <aurelien@aurel32.net> wrote:
> [ Sorry to come back so late about this commit ]
>
> On 2017-10-19 08:27, H.J. Lu wrote:
>> On Thu, Oct 19, 2017 at 7:51 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>
>> >> +ifneq (no,$(have-tunables))
>> >> +tests += tst-platform-1
>> >> +modules-names += tst-platformmod-1 x86_64/tst-platformmod-2
>> >> +CFLAGS-tst-platform-1.c = -mno-avx
>> >> +CFLAGS-tst-platformmod-1.c = -mno-avx
>> >> +CFLAGS-tst-platformmod-2.c = -mno-avx
>> >> +LDFLAGS-tst-platformmod-2.so = -Wl,-soname,tst-platformmod-2.so
>> >> +$(objpfx)tst-platform-1: $(objpfx)tst-platformmod-1.so
>> >> +$(objpfx)tst-platform-1.out: $(objpfx)x86_64/tst-platformmod-2.so
>> >> +# Turn off AVX512F_Usable and AVX2_Usable so that GLRO(dl_platform) is
>> >> +# always set to x86_64.
>> >> +tst-platform-1-ENV = LD_PRELOAD=$(objpfx)\$$PLATFORM/tst-platformmod-2.so
>> >> \
>> >> +       GLIBC_TUNABLES=glibc.tune.hwcaps=-AVX512F_Usable,-AVX2_Usable
>> >> +endif
>> >
>> >
>> > Does this build $(objpfx)/tst-platformmod-2.so?  I think this would
>>
>> No.  x86_64/tst-platformmod-2, not tst-platformmod-2, is added to
>> modules-names.
>>
>> [hjl@gnu-6 build-x86_64-linux]$ find -name tst-platformmod-2.so
>> ./elf/x86_64/tst-platformmod-2.so
>> [hjl@gnu-6 build-x86_64-linux]$
>
> This assumes that the platform for sysdeps/x86_64 is always "x86_64".
> This is actually wrong for x32 for where it is set to i686. This causes
> the test to fail on x32.
>

It is wrong for kernel to set AT_PLATFORM to i686.   Should we fix it
in glibc or in kernel?

-- 
H.J.


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