On 30/06/18 08:16, Andrew Jones wrote: > On Fri, Jun 29, 2018 at 05:17:57PM +0100, Sudeep Holla wrote: >> Currently we use the ACPI processor ID only for the leaf/processor nodes >> as the specification states it must match the value of ACPI processor ID >> field in the processor’s entry in the MADT. >> >> However, if a PPTT structure represents processors group, it match a >> processor container UID in the namespace and ACPI_PPTT_ACPI_PROCESSOR_ID_VALID >> flag describe whether the ACPI processor ID is valid. >> >> Lets use UID whenever ACPI_PPTT_ACPI_PROCESSOR_ID_VALID is set to be >> consistent instead of using table offset as it's currently done for non >> leaf nodes. >> >> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> >> Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx> >> --- >> drivers/acpi/pptt.c | 10 ++++++++-- >> 1 file changed, 8 insertions(+), 2 deletions(-) >> >> Hi, >> >> There's ongoing discussion on assigning ID based in OS using simple >> counters. It can never be consistent with firmware's view. So if the >> firmware provides valid UID for non-processors node, we must use it. > > I agree with this. I've been so focused on the fact that the ACPI offsets > are arbitrary, and thus counters can't be worse, that I nearly forgot how > these IDs are actually defined: > Yes, it's platform dependent and I now realize that I never explicitly mentioned that, let alone emphasize on that. I was for UID for the same reason. [...] > > When the valid flag is set we'll now return a [hopefully] correct platform > dependent ID, but when it's not we'll return an ACPI table offset. How > will users of the ID know? Also, it's possible to return -ENOENT for the > ID when calling find_acpi_cpu_topology(). How can we distinguish that from > an arbitrary platform dependent ID? > But why should one need to distinguish that ? Even offset is kind of sparsely distributed UID. -- Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
