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

[Florian Weimer]

On 10/04/2016 08:13 PM, Adhemerval Zanella wrote:
> 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.

As far as I understand it, the issue is that the trampoline writes to 
the SSE/AVX/AVX2 registers, which clears the AVX-512F bits (which are 
not saved by the trampoline).

Intel introduced AVX512F in such a manner that you have to upgrade 
kernel and userspace in lock-step, which is of course unrealistic.

Florian