From mboxrd@z Thu Jan 1 00:00:00 1970 From: jeremy.linton@arm.com (Jeremy Linton) Date: Mon, 2 Jul 2018 09:41:54 -0500 Subject: [PATCH] ACPI/PPTT: use ACPI ID whenever ACPI_PPTT_ACPI_PROCESSOR_ID_VALID is set In-Reply-To: <3895a0d8-9cca-2512-a06e-0ee2ac7db773@arm.com> References: <1530289077-2444-1-git-send-email-sudeep.holla@arm.com> <3895a0d8-9cca-2512-a06e-0ee2ac7db773@arm.com> Message-ID: <45daa83a-08de-24e5-c3de-35046afa33a1@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On 07/02/2018 04:57 AM, Sudeep Holla wrote: > > > On 02/07/18 10:06, Rafael J. Wysocki wrote: >> On Fri, Jun 29, 2018 at 6:17 PM, 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" >>> Signed-off-by: Sudeep Holla >>> --- >>> 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. >> >> OK >> >> Do you regard this as a fix for the recently merged PPTT material? If >> so, I should apply it as a fix for 4.18. >> > > Yes, it should be considered as fix IMO. Do we know which machines are affected? I'm mostly agnostic to this patch because I believe its effectively a NOP. But that said, it could have a functional change, which implies there is some risk.