On Fri, Jun 29, 2018 at 05:46:08PM +0200, Andrew Jones wrote: > On Fri, Jun 29, 2018 at 02:29:34PM +0100, Sudeep Holla wrote:
[..] > > > > How is that different from OS generated one from user's perspective ? > > Vendors might assign sockets UID and he may help them to replace one. > > Having some generated counter based id is not helpful. > > I agree with this. It's a good argument for maintaining a mapping of > package-id to id-physically-printed-on-a-package somewhere. To avoid > maintaining a mapping it could just be stored directly in > cpu_topology[cpu].package_id, but then how can we tell the difference > between a valid printed-on-package-id and an ACPI offset? We'd still > have to maintain additional state to determine if it's valid or not, > so we could just maintain a mapping instead. > x86 may have a architectural way to obtain it and hence they don't need to rely on PPTT. But for ARM, we need to rely on PPTT for it and if vendors/users need accurate information, it has to come from PPTT and any other place is never going to be consistent and hence unusable. So, even though specification doesn't mandate, I think OS should as it's the only robust way. We can get the firmware fixed/updated if random unique number hurts. Firmware is not upgradeable is no longer a valid argument. -- Regards, Sudeep
