[PATCH 6/7] wineboot: Initialize XState features in user_shared_data.

[Paul Gofman]

On 5/27/21 03:00, Francois Gouget wrote:
> On Wed, 26 May 2021, Paul Gofman wrote:
>
>> FWIW the tests succeed on real hardware for me (64 bit, xstate
>> supported) on Win7 and Win10 (latest; the broken case is not hit).
> So it would be interesting to tease out the differences between your 
> machines and the ones I have access to.
>
> What is your CPU? Maybe Windows 10 only sets these fields for recent 
> enough CPUs?
>
> You said you have all the latest updates. The most recent Windows 10 
> version I have is 2009 with all the updates up to 2021-05-03. Do you 
> have 21H1 already?
>
> Can you think of other aspects that could make a difference?
>
>
I have AMD Ryzen 5 3500X, Windows 10 Pro, 20H2 Build 19042.985.
Everything was the same with these test results at the moment of writing
the original patch. Maybe this depends on CPU feature flags, or AVX2. As
far as I looked up, i7-2600K is from early 2010s and doesn't support
AVX2, maybe it doesn't support some other xstate related features like
xsavec or xsaveopt (I don't have a full cpuid for that CPU to be sure).
I am not sure that this internal field behaviour CPU dependence worth
supporting, and thus not sure it worth spending a lot of time
investigating. If this is a matter of justifying the 'broken' statement,
I am open to any variant which is best for the (probably not unique)
case when we don't know for sure why it differs, like removing check for
this field, marking both results as non-broken or changing the comment.