Re: [Xen-devel] xsave=0 workaround needed on 3.2 kernels with Xen 4.1 or Xen-unstable.

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

>> Ironically, the code in init-arch used to look like:
>>
>>
>>  if (__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & bit_AVX)
>>    {
>>
>>      /* Reset the AVX bit in case OSXSAVE is disabled.  */
>>      if ((__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & bit_OSXSAVE) ==
>> 0
>>          || ({ unsigned int xcrlow;
>>              unsigned int xcrhigh;
>>              asm ("xgetbv"
>>
>>                   : "=a" (xcrlow), "=d" (xcrhigh) : "c" (0));
>>              (xcrlow & 6) != 6; }))
>>
>>        __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx &= ~bit_AVX;
>>    }
>>
>>
>> Which I think would have done the right thing.   Uli changed it to the
>> form you quoted just 2 hours after installing the version I quoted.
>
> Sadly no as it would have executed the xgetv instruction. Since the first
> part of the boolean logic returns false.

<sigh> And that is what I get from typing this while stopping at
lights and being in a hurry and doing this on a cellphone.
Please ignore what I said above - the earlier version would have worked correct.

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