Re: [Xen-devel] [PATCH] x86: avoid HPET use on certain Intel platforms

[Jan Beulich <jbeulich@xxxxxxxx>]

On 22.11.2019 13:50, Andrew Cooper wrote:
> On 22/11/2019 12:46, Jan Beulich wrote:
>> Linux commit fc5db58539b49351e76f19817ed1102bf7c712d0 says
>>
>> "Some Coffee Lake platforms have a skewed HPET timer once the SoCs entered
>>  PC10, which in consequence marks TSC as unstable because HPET is used as
>>  watchdog clocksource for TSC."
>>
>> Follow this for Xen as well. Looking at its patch context made me notice
>> they have a pre-existing quirk for Bay Trail as well. The comment there,
>> however, points at a Cherry Trail document. Looking at the datasheets of
>> both, there appear to be similar issues, so go beyond Linux'es coverage
>> and exclude both. Also key the disable on the PCI IDs of the actual
>> affected devices, rather than those of 00:00.0.
>>
>> Apply the workarounds only when the use of HPET was not explicitly
>> requested on the command line and when use of (deep) C-states was not
>> disabled.
>>
>> Adjust a few types in touched or nearby code at the same time.
> 
> Reported-by ?

The Linux commit has a Suggested-by, but no Reported-by. Do you
want me to copy that one? Or else do you have any suggestion as
to who the reporter was?

>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks.

Jan

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