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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.11.2019 13:29, 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.  What is it on the 3700X if
>> you don't change it here?
> 
> According to the CPUID output Andreas had sent it's 4. The
> current massaging in libxc (which your patch would conditionally
> suppress) would double this to 8 afaict.

Ouch, no - it would increment it (to 5), not double it.

Jan

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