[Xen-devel] RE: [PATCH] CPUID level 0x00000007:0 (ebx) is word 9, instead of word 7

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 31.05.11 at 16:59, "Li, Xin" <xin.li@xxxxxxxxx> wrote:
>> can't see why we would need to stay in sync with Linux's capability
>> array indices.
> 
> why?  Typically we reuse Linux code unless Xen has its special logic.

So you would suggest leaving indices 7 and 8 unused instead?
Looking at current Linux, we certainly could convert Xen to use
index 8 for virtualization features, but since these are being
tracked differently already anyway I don't see a value in this.

As to index 7, just look at ARAT - we're already diverging from
Linux here (having it allocated in index 3).

Bottom line is that I think keeping the names (and in various cases
the grouping together, namely when the bits are grouped together
in some CPUID leaf's output) in sync is desirable, but following
Linux to the bit doesn't always make sense. After all, some thinking
will always be necessary when porting over patches.

Jan


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