Re: [Xen-devel] Question about the CAT and CMT in Xen

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Meng Xu <xumengpanda@xxxxxxxxx> 09/02/15 4:57 AM >>>
>2015-09-01 22:31 GMT-04:00 Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>:
>> On Tue, Sep 01, 2015 at 09:51:57PM -0400, Meng Xu wrote:
>>> Hi Andrew and Chao,
>>>
>>> [Important things go first] It turns out my machine (Intel E5-2618L
>>> v3) does have CAT capability!
>>> Xen gives the false alarm that my machine does not have it. This
>>> should be a bug, IMO. :-)
>>
>> Even some Haswell Servers do support CAT, but it's usually
>> model-specific and the feature is not enumerated in a standard way as
>> listed in Intel SDM. Xen now however only takes care of the standard
>> enumeration so your case is not detected.
>
>Ah. I prefer not to upgrade the firmware... Last time when I upgrade
>the firmware, I screw up the whole system. :-(

I would very much expect this to be an exception, not the norm.

>Is it possible to check if CAT is supported on a machine with another
>way? Right now, I think you are checking some specific bits returned
>by CPUID.

That's the one and only way it should be done in production software.
For your own debugging/development purposes you could of course
extend that check.

Jan


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