On 01.03.2023 19:01, Sergey Dyasli wrote: > On Wed, Mar 1, 2023 at 11:31 AM Jan Beulich <jbeul...@suse.com> wrote: >> >> On 28.02.2023 18:39, Sergey Dyasli wrote: >>> Add an option to xen-ucode tool to print the currently loaded ucode >>> version and also print it during usage info. Print CPU signature and >>> processor flags as well. The raw data comes from cpuinfo directory in >>> xenhypfs and from XENPF_get_cpu_version platform op. >> >> While I don't mind the use of the platform-op, I'm little puzzled by the >> mix. If CPU information is to be exposed in hypfs, can't we expose there >> everything that's needed here? >> >> Then again, perhaps in a different context, Andrew pointed out that hypfs >> is an optional component, so relying on its presence in the underlying >> hypervisor will need weighing against the alternative of adding a new >> platform-op for the ucode-related data (as you had it in v1). Since I'm >> unaware of a request to switch, are there specific reasons you did? > > Ideal situation would be microcode information in Dom0's /proc/cpuinfo > updated after late load, since that file already has most of the > information about the cpu. And the closest thing to /proc is xenhypfs. > It allows the user to query information directly, e.g. > > # xenhypfs cat /cpuinfo/microcode-revision > 33554509 > > Which could be used manually or in scripts, instead of relying on > xen-ucode utility. Though printing the value in hex would be nicer. > That was my motivation to go hypfs route. In general it feels like cpu > information is a good fit for hypfs, but agreement on its format and > exposed values is needed. > I can always switch back to a platform op if that would be the preference.
I've confirmed with Andrew that I was remembering correctly and he would not want to see a dependency on hypfs in such a tool. Since it's optional in the hypervisor, you'd need an alternative source of the same info anyway, and hence you can as well go just that non-hypfs route. FTAOD: This isn't to say that some CPU info wouldn't be useful to expose in hypfs. But that's then an independent task. Jan
