Re: [PATCH 1/3] acpi/processor: fix evaluating _PDC method when running as Xen dom0

[Dave Hansen <dave.hansen@xxxxxxxxx>]

On 11/21/22 02:21, Roger Pau Monne wrote:
> When running as a Xen dom0 the number of CPUs available to Linux can
> be different from the number of CPUs present on the system, but in
> order to properly fetch processor performance related data _PDC must
> be executed on all the physical CPUs online on the system.

How is the number of CPUs available to Linux different?

Is this a result of the ACPI tables that dom0 sees being "wrong"?

> The current checks in processor_physically_present() result in some
> processor objects not getting their _PDC methods evaluated when Linux
> is running as Xen dom0.  Fix this by introducing a custom function to
> use when running as Xen dom0 in order to check whether a processor
> object matches a CPU that's online.

What is the end user visible effect of this problem and of the solution?