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Re: [PATCH x86_64][BZ #20139] Don't allow configure with not supporting AVX512 assembler w/o --disable-avx512.
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Florian Weimer <fweimer at redhat dot com>
- Cc: Andrew Senkevich <andrew dot n dot senkevich at gmail dot com>, libc-alpha <libc-alpha at sourceware dot org>
- Date: Mon, 27 Jun 2016 11:29:08 -0700
- Subject: Re: [PATCH x86_64][BZ #20139] Don't allow configure with not supporting AVX512 assembler w/o --disable-avx512.
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- References: <CAMXFM3tJkhW78PPe4=FUhbm=8HoOY4iouSqXxLObA0GEMTxoZA at mail dot gmail dot com> <5ecbe6ab-79a9-7bf4-909b-3b61d0877559 at redhat dot com> <CAMXFM3tp-hDH5zNOO=eZAELbmuQbaWCrEo1JWM-ETCwTNb5RVA at mail dot gmail dot com> <b03e2738-6c7c-4036-a3f4-e8c55039c4cf at redhat dot com>
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.