Re: [PATCH 1/1] Add AVX512 support for xbzrle_encode_buffer function

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Jul 22, 2022 at 02:23:13AM +0000, Zhao, Zhou wrote:
> 1 we need gcc machined options to tirgger gcc enable SIMD
> instructions(https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html).
> Or it will trigger a compile error. This is the reason why we
> change the config file.

Take a look at util/bufferiszero.c   - that uses '#pragma GCC target'
to selectively change the compule target of individual functions.

This is what is njeeded here, because most distros are going to
compile QEMU with a very old x86_64 baseline, never turn on avx512
for the whole QEMU build. It needs to be very selective to make
it usable for typical deployments.

With regards,
Daniel
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