Re: [PATCH v2 07/22] arm64: Keep track of CPU feature registers

From: Suzuki K. Poulose
Date: Mon Oct 12 2015 - 13:01:34 EST


On 08/10/15 16:03, Catalin Marinas wrote:
On Thu, Oct 08, 2015 at 10:55:11AM +0100, Suzuki K. Poulose wrote:

...

So we have three types of fields in these registers:

a) features defined but not something we care about in Linux
b) reserved fields
c) features important to Linux

I guess for (a), Linux may not even care if they don't match (though we
need to be careful which fields we ignore). As for (b), even if they
differ, since we don't know the meaning at this point, I think we should
just ignore them. If, for example, they add a feature that Linux doesn't
care about, they practically fall under the (a) category.

Regarding exposing reserved CPUID fields to user, I assume we would
always return 0.

Mark,

Do you have any comments on this ? The list I have here is what you came
up with in SANITY checks.

Thanks
Suzuki

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