[PATCH] X86-64: Add _dl_runtime_resolve_avx[512]_opt [BZ #20508]

[Florian Weimer]

On 10/04/2016 06:08 PM, H.J. Lu wrote:
>>>>> Good question.  This is also needed:
>>>>>
>>>>> commit f43cb35c9b3c35addc6dc0f1427caf51786ca1d2
>>>>> Author: H.J. Lu <hjl.tools@gmail.com>
>>>>> Date:   Fri Jul 1 05:54:43 2016 -0700
>>>>>
>>>>>     Require binutils 2.24 to build x86-64 glibc [BZ #20139]
>>
>>
>>>> That's not really backportable, I'm afraid.  Our users don't expect we
>>>> break
>>>> builds in this way.
>>>>
>>>
>>> Who are those users?
>>
>>
>> We don't know, really.  But moving forward the baseline binutils requirement
>> in a stable release really contradicts what a stable release is about.

> Do our users expect a broken glibc binary of a stable release on AVX512
> machine?

Either switch to the XSAVE approach, or encode the relevant opcodes 
using .byte.

We used the latter in Red Hat Enterprise Linux 6, and I'm attaching our 
patch in case it is helpful.

Florian

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