Re: [Xen-devel] Ryzen 3xxx works with Windows

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.11.2019 16:15, George Dunlap wrote:
> On 11/18/19 12:54 PM, Jan Beulich wrote:
>> On 18.11.2019 12:39, George Dunlap wrote:
>>> On 11/15/19 5:06 PM, Andreas Kinzler wrote:
>>>> Hello All,
>>>>
>>>> I compared the CPUID listings from Ryzen 2700X (attached as tar.xz) to
>>>> 3700X and found only very few differences. I added
>>>>
>>>> cpuid = [ "0x80000008:ecx=xxxxxxxxxxxxxxxx0100xxxxxxxxxxxx" ]
>>>>
>>>> to xl.cfg and then Windows runs great with 16 vCPUs. Cinebench R15 score
>>>> is >2050 which is more or less the bare metal value.
>>>
>>> So this is setting those bits to 0100, or 4.
>>
>> One of the many possible problems with our incrementing of this field
>> could be that this results in a value that in "reserved" as per AMD's
>> documentation. At least for some of the Fam17 models they document
>> exactly which values are "legal".
> 
> Do you have a reference for this?

Unfortunately none that I can share. But you can bet that OS vendors use
that rather than the public variant(s) for their development work.

Jan

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