On Thu, Sep 7, 2023 at 9:20 AM Wilczynski, Michal michal.wilczynski@intel.com wrote:
Hi,
On 9/6/2023 8:21 PM, Jason Andryuk wrote:
From: Roger Pau Monne roger.pau@citrix.com
The Processor _PDC buffer bits notify ACPI of the OS capabilities, and so ACPI can adjust the return of other Processor methods taking the OS capabilities into account.
_PDC method is deprecated for this purpose, since 2018, and is dropped from spec since 6.5
We made the switch in linux since 6.6: 95272641338a ("ACPI: processor: Use _OSC to convey OSPM processor support information")
Thanks for the heads up, Michal. The patch pre-dated 6.6 and I based this one off of 6.5.
When Linux is running as a Xen dom0, it's the hypervisor the entity in charge of processor power management, and hence Xen needs to make sure the capabilities reported in the _PDC buffer match the capabilities of the driver in Xen.
So I guess you would need to sanitize buffer passed to _OSC method instead ?
I think I'll modify the capabilities in arch_acpi_set_proc_cap_bits() and that will handle both _OSC and the _PDC fallback.
Regards, Jason