On Wed, Aug 9, 2023 at 3:17 PM Jan Beulich <jbeul...@suse.com> wrote: > > On 09.08.2023 04:14, Hongtao Liu wrote: > > On Wed, Aug 9, 2023 at 9:21 AM Hongtao Liu <crazy...@gmail.com> wrote: > >> > >> On Wed, Aug 9, 2023 at 3:55 AM Joseph Myers <jos...@codesourcery.com> > >> wrote: > >>> > >>> Do you have any comments on the interaction of AVX10 with the > >>> micro-architecture levels defined in the ABI (and supported with > >>> glibc-hwcaps directories in glibc)? Given that the levels are cumulative, > >>> should we take it that any future levels will be ones supporting 512-bit > >>> vector width for AVX10 (because x86-64-v4 requires the current AVX512F, > >>> AVX512BW, AVX512CD, AVX512DQ and AVX512VL) - and so any future processors > >>> that only support 256-bit vector width will be considered to match the > >>> x86-64-v3 micro-architecture level but not any higher level? > >> This is actually something we really want to discuss in the community, > >> our proposal for x86-64-v5: AVX10.2-256(Implying AVX10.1-256) + APX. > >> One big reason is Intel E-core will only support AVX10 256-bit, if we > >> want to use x86-64-v5 accross server and client, it's better to > >> 256-bit default. > > Aiui these ABI levels were intended to be incremental, i.e. higher versions > would include everything earlier ones cover. Without such a guarantee, how > would you propose compatibility checks to be implemented in a way Are there many software implemenation based on this assumption? At least in GCC, it's not a big problem, we can adjust code for the new micro-architecture level. > applicable both forwards and backwards? If a new level is wanted here, then > I guess it could only be something like v3.5. But if we use avx10.1 as v3.5, it's still not subset of x86-64-v4(avx10.1 contains avx512fp16,avx512bf16 .etc which are not in x86-64-v4), there will be still a diverge. Then 256-bit of x86-64-v4 as v3.5? that's too weired to me.
Our main proposal is to make AVX10.x as new micro-architecture level with 256-bit default, either v3.5 or v5 would be acceptable if it's just the name. > > Jan -- BR, Hongtao
