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Re: [PATCH] X86-64: Add _dl_runtime_resolve_avx[512]_opt [BZ #20508]
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Tue, 4 Oct 2016 15:13:08 -0300
- Subject: Re: [PATCH] X86-64: Add _dl_runtime_resolve_avx[512]_opt [BZ #20508]
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOojpuFz1jTbMpNcqZK1KVDqaWozNuEuS3E67dvD3Rh=hw@mail.gmail.com> <c6e21847-bc95-3c75-ed54-798c62194072@redhat.com> <CAMe9rOp=bvrk0MBF8SrP4JqLHembRdeyfGNqNkcVWvoEs3R=tA@mail.gmail.com> <CAMe9rOo7MmGNPKct=AzzbtR564yH1P96tUcLD7pFv7GtxF3-Ng@mail.gmail.com> <48eeea78-99e8-f255-bd26-b6d28929b4f0@twiddle.net> <CAMe9rOqXhVLVbT90JBfkJnCLzZBrkUHtkO4Ddfk9HPH7jiyEzw@mail.gmail.com> <CAMe9rOoDp7XYwLdDetFNghAdDo_zj-4342LKV4i0zCH36aBWtw@mail.gmail.com> <CAMe9rOo+_TQABBp0eC4nQcJ5ENLrZAOSvtAjo17E6H0ezDpWvg@mail.gmail.com> <CAMe9rOqoATTPzXqjtqenV0h+hMtMYcr+W-ZL3Bi4jFJWYBCUpg@mail.gmail.com> <76f9e5c1-d1de-04d1-49f5-30673bf3060b@redhat.com> <CAMe9rOq8yu+b0-N6UR3vb843NApZ+ZjBwAw5GsERHpvuCrVjrw@mail.gmail.com> <14cc7a47-1a39-6285-d4b5-dab2769c092b@redhat.com> <CAMe9rOrqmLmHLhHL7pDSvR=8=dUUGP07zY5A3DiOubtpvR25WQ@mail.gmail.com> <ea7fe73f-b8cb-6049-d4c4-918d724bd883@redhat.com> <CAMe9rOqxqffhZAb1Sj-qxg_1oU0J=0v7rvhoXVbjbJrrthHucg@mail.gmail.com>
On 04/10/2016 13:08, H.J. Lu wrote:
> On Tue, Oct 4, 2016 at 8:48 AM, Florian Weimer <fweimer@redhat.com> wrote:
>> On 10/04/2016 05:34 PM, H.J. Lu wrote:
>>>
>>> On Tue, Oct 4, 2016 at 8:24 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>>>
>>>> On 10/04/2016 04:47 PM, H.J. Lu wrote:
>>>>>
>>>>>
>>>>> On Tue, Oct 4, 2016 at 3:52 AM, Florian Weimer <fweimer@redhat.com>
>>>>> wrote:
>>>>>>
>>>>>>
>>>>>> On 09/27/2016 07:35 PM, H.J. Lu wrote:
>>>>>>
>>>>>>>> Any comments? I will check it in next week if there is no objection.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> I'd like to backport it to 2.23 and 2.24 branches. Any objections?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Just this change, or the requirement for an AVX512F-capable assembler
>>>>>> as
>>>>>> well?
>>>>>>
>>>>>
>>>>> 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?
>
I think 2.24 it is ok since it contains the BZ#20139 fix already. For 2.23,
although it was not really explicit in NEWS, AVX512 is suppose to be supported
in a set of different implementation (memmove/memcpy/libmvec). However my
understanding of this issue is limited to be a performance one, so I do not
see a pressing matter to change a release requirements for such change.