On 19.05.2025 10:36, Penny, Zheng wrote: > [Public] > >> -----Original Message----- >> From: Jan Beulich <[email protected]> >> Sent: Tuesday, April 29, 2025 8:52 PM >> To: Penny, Zheng <[email protected]> >> Cc: Huang, Ray <[email protected]>; Andrew Cooper >> <[email protected]>; Anthony PERARD <[email protected]>; >> Orzel, Michal <[email protected]>; Julien Grall <[email protected]>; Roger >> Pau >> Monné <[email protected]>; Stefano Stabellini <[email protected]>; >> xen- >> [email protected] >> 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). Jan
