[Public] > -----Original Message----- > From: Jan Beulich <jbeul...@suse.com> > Sent: Tuesday, May 20, 2025 5:16 PM > To: Penny, Zheng <penny.zh...@amd.com> > Cc: Huang, Ray <ray.hu...@amd.com>; Andrew Cooper > <andrew.coop...@citrix.com>; Anthony PERARD <anthony.per...@vates.tech>; > Orzel, Michal <michal.or...@amd.com>; Julien Grall <jul...@xen.org>; Roger Pau > Monné <roger....@citrix.com>; Stefano Stabellini <sstabell...@kernel.org>; > xen- > de...@lists.xenproject.org > Subject: Re: [PATCH v4 05/15] xen/x86: introduce "cpufreq=amd-cppc" xen > cmdline > > On 20.05.2025 10:28, Penny, Zheng wrote: > > [Public] > > > >> -----Original Message----- > >> From: Jan Beulich <jbeul...@suse.com> > >> Sent: Monday, May 19, 2025 9:19 PM > >> To: Penny, Zheng <penny.zh...@amd.com> > >> Cc: Huang, Ray <ray.hu...@amd.com>; Andrew Cooper > >> <andrew.coop...@citrix.com>; Anthony PERARD > >> <anthony.per...@vates.tech>; Orzel, Michal <michal.or...@amd.com>; > >> Julien Grall <jul...@xen.org>; Roger Pau Monné > >> <roger....@citrix.com>; Stefano Stabellini <sstabell...@kernel.org>; > >> xen- de...@lists.xenproject.org > >> Subject: Re: [PATCH v4 05/15] xen/x86: introduce "cpufreq=amd-cppc" > >> xen cmdline > >> > >> On 19.05.2025 10:36, Penny, Zheng wrote: > >>> [Public] > >>> > >>>> -----Original Message----- > >>>> From: Jan Beulich <jbeul...@suse.com> > >>>> Sent: Tuesday, April 29, 2025 8:52 PM > >>>> To: Penny, Zheng <penny.zh...@amd.com> > >>>> Cc: Huang, Ray <ray.hu...@amd.com>; Andrew Cooper > >>>> <andrew.coop...@citrix.com>; Anthony PERARD > >>>> <anthony.per...@vates.tech>; Orzel, Michal <michal.or...@amd.com>; > >>>> Julien Grall <jul...@xen.org>; Roger Pau Monné > >>>> <roger....@citrix.com>; Stefano Stabellini > >>>> <sstabell...@kernel.org>; > >>>> xen- de...@lists.xenproject.org > >>>> Subject: Re: [PATCH v4 05/15] xen/x86: introduce "cpufreq=amd-cppc" > >>>> xen cmdline > >>>> > >>>> On 14.04.2025 09:40, Penny Zheng wrote: > >>>>> --- a/xen/include/acpi/cpufreq/processor_perf.h > >>>>> +++ b/xen/include/acpi/cpufreq/processor_perf.h > >>>>> @@ -5,6 +5,9 @@ > >>>>> #include <public/sysctl.h> > >>>>> #include <xen/acpi.h> > >>>>> > >>>>> +/* ability bits */ > >>>>> +#define XEN_PROCESSOR_PM_CPPC 8 > >>>> > >>>> This needs correlating (at least via commentary, better by > >>>> build-time > >>>> checking) with the other XEN_PROCESSOR_PM_* values. Otherwise > >> someone > >>>> adding a new #define in the public header may not (easily) notice a > >>>> possible conflict. With that in mind I also question whether 8 is > >>>> actually a good choice: That's the obvious next value to use in the > >>>> public interface. SIF_PM_MASK is 8 bits wide, so a sensible value > >>>> to use here > >> would by e.g. 0x100. > >>>> > >>> > >>> I've added a public flag anchor "XEN_PROCESSOR_PM_PUBLIC_END" in > >> public header: > >>> #define XEN_PROCESSOR_PM_PUBLIC_END > >> XEN_PROCESSOR_PM_TX > >>> and will do the following build-time checking: > >>> BUILD_BUG_ON(XEN_PROCESSOR_PM_CPPC <= > >>> XEN_PROCESSOR_PM_PUBLIC_END); > >> > >> I don't really see why anything would need to be added to the public > >> header (and we really should strive to avoid unnecessary additions). > > > > If I put such definition > > "#define XEN_PROCESSOR_PM_PUBLIC_END XEN_PROCESSOR_PM_TX" > > in internal header, I'm afraid it won't be updated if new ones added in the > > public in > the future. > > Or any other suggestions to provide build-time checking? > > Imo it's sufficient to check that the new #define doesn't overlap with > SIF_PM_MASK.
Understood! > > Jan
