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Re: [PATCH v3 1/2] Fetch XSAVE area component offsets and sizes when initializing x86 CPU

On Sun, 2019-06-09 at 12:54 +0200, Maxime Villard wrote:
> Le 09/06/2019 à 09:33, Michał Górny a écrit :
> > On Sun, 2019-06-09 at 09:20 +0200, Maxime Villard wrote:
> > > In fact, the whole loop seems wrong: CPUID uses the XCR0_ constants, not the
> > > XSAVE_ constants. Eg HDC is 13 in XCR0_ but 10 in XSAVE_, so you never iterate
> > > over it.
> > 
> > It's intentional.  I only iterate up to XSAVE_MAX_COMPONENT,
> > i.e. the last component actually used by the kernel.  I don't skip
> > earlier unused components to avoid index madness but I see no purpose to
> > go beyond last component actually used.
> Ok, that's fine for now and we can revisit that later for future states.
> However, maybe rename XSAVE_ -> XCRO_SHIFT_, or something else, to make it
> clear that this depends on the hardware layout.

It is meant to be 'XSAVE component index', to be precise.  As passed
e.g. to CPUID as ECX.

Best regards,
Michał Górny

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