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Re: [PATCH x86_64][BZ #20139] Don't allow configure with not supporting AVX512 assembler w/o --disable-avx512.

On 06/27/2016 08:29 PM, H.J. Lu wrote:


If ld.so doesn't the first 8 save/store ZMM registers, you
may not pass parameters in ZMM registers with AVX512
kernel on AVX512 machine.   We wan to make sure that
ld.so in x86-64 glibc saves/stores ZMM registers unless
glibc is configured to disable AVX512 support.


I still do not understand what is going on.
What can clobber the ZMM registers if glibc was compiled without AVX-512 capabilities?
If ld.so support for AVX512 is a must before applications can use it, why has this not been built into the platform capability detection mechanism? 

Thanks,
Florian
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