[PATCH x86_64][BZ #20139] Don't allow configure with not supporting AVX512 assembler w/o --disable-avx512.

[H.J. Lu]

On Mon, Jun 27, 2016 at 11:20 AM, Florian Weimer <fweimer@redhat.com> wrote:
> On 06/27/2016 08:15 PM, Andrew Senkevich wrote:
>>
>> 2016-06-27 21:03 GMT+03:00 Florian Weimer <fweimer@redhat.com>:
>>>
>>> On 06/27/2016 07:40 PM, Andrew Senkevich wrote:
>>>>
>>>>
>>>> To fix BZ #20139 we need don't let to configure with not supporting
>>>> AVX512 assembler w/o --disable-avx512.
>>>
>>>
>>>
>>> There is an existing configure check for HAVE_AVX512_ASM_SUPPORT.  Why
>>> isn't
>>> it sufficient?
>>
>>
>> Where are bug https://sourceware.org/bugzilla/show_bug.cgi?id=20139
>> It is the case when HAVE_AVX512_ASM_SUPPORT is undefined and Glibc is
>> built for AVX512 hardware.
>
>
> It's still unclear to me what you are proposing as a remedy.
>
> Building glibc with --disable-avx512 will still be broken, no?
>

If ld.so doesn't the first 8 save/store ZMM registers, you
may not pass parameters in ZMM registers with AVX512
kernel on AVX512 machine.   We wan to make sure that
ld.so in x86-64 glibc saves/stores ZMM registers unless
glibc is configured to disable AVX512 support.

-- 
H.J.