[PATCH v1 1/1] Set Prefer_No_AVX512 flag for hygon platform

[Jiamei Xie]

Hi Florian，

> -----Original Message-----
> From: Florian Weimer <fweimer@redhat.com>
> Sent: 2025年10月14日 16:26
> To: Jiamei Xie <xiejiamei@hygon.cn>
> Cc: libc-alpha@sourceware.org; Jing Li <lijing@hygon.cn>
> Subject: Re: [PATCH v1 1/1] Set Prefer_No_AVX512 flag for hygon platform
> 
> * Jiamei Xie:
> 
> >> And surely this must be under the HygonGenuine condition?
> >>
> >
> > Yes. This patch is for the Hygon Platform, whose model is 0x7.
> 
> Ahh.  Is that really unique?  I would have expected that this check would be
> reuse:
> 
>   /* This spells out "HygonGenuine".  */
>   else if (ebx == 0x6f677948 && ecx == 0x656e6975 && edx == 0x6e65476e)
>     {
> 

AFAIK, "HygonGenuine" is the vendor ID, and the model number identifies a specific CPU model. Hygon has multiple models.

In our testing, Hygon model 0x7 does not perform well on AVX-512.
In the future, there may be models that support AVX-512 and outperform EVEX.

Therefore, I believe it’s appropriate to guard this logic under a model check.

> Thanks,
> Florian
>