RE: [PATCH v2 1/1] arm64: Add workaround for Fujitsu A64FX erratum 010001

[Zhang, Lei]

Hi Catalin,
> -----Original Message-----
> From: linux-arm-kernel
> [mailto:linux-arm-kernel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Catalin Marinas
> Sent: Saturday, January 26, 2019 3:08 AM
> To: Zhang, Lei/張 雷
> Cc: 'Mark Rutland'; 'will.deacon@xxxxxxx';
> 'linux-kernel@xxxxxxxxxxxxxxx';
> 'linux-arm-kernel@xxxxxxxxxxxxxxxxxxx'
> Subject: Re: [PATCH v2 1/1] arm64: Add workaround for Fujitsu A64FX
> erratum 010001
> 
> IIUC, this can happen very early when the errata framework isn't yet
> ready. Given that this is not on a fast path (you already took a fault),
> I don't think it's worth optimising for cpus_have_cap() (and
> ARM64_WORKAROUND_FUJITSU_A64FX_0100001). I've seen Mark's comments on
> why checking MIDR in a preemptible context is not a good idea but I
> suspect your platform is homogeneous (i.e. not big.LITTLE).
Thanks for comment.
I will post a new patch to resolve fast path problem in today.
By the way our platform is homogeneous.


Best Regards,
Lei Zhang
zhang.lei@xxxxxxxxxxxxxx