Hi,
On 06/29/2018 11:17 AM, 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.
Regards,
Sudeep
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index e5ea1974d1e3..d1e26cb599bf 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -481,8 +481,14 @@ static int topology_get_acpi_cpu_tag(struct acpi_table_header *table,
if (cpu_node) {
cpu_node = acpi_find_processor_package_id(table, cpu_node,
level, flag);
- /* Only the first level has a guaranteed id */
- if (level == 0)
+ /*
+ * As per specification if the processor structure represents
+ * an actual processor, then ACPI processor ID must be valid.
+ * For processor containers ACPI_PPTT_ACPI_PROCESSOR_ID_VALID
+ * should be set if the UID is valid
+ */
+ if (level == 0 ||
+ cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID)
return cpu_node->acpi_processor_id;
While, for some machines this likely helps create more human readable
ID's... What happens when the ID namespaces conflict with each other?
AKA, I'm a little shy of this change because your going from something
we can guarantee is unique to depending on an portion of the PPTT
definition that has a couple different ways that it can be interpreted.
OTOH the change is probably safe at the moment because i don't think
anyone has partially marked nodes at a given PPTT "level" valid, or put
structures that aren't part of the PE/cache's in the tree (outside of my
juno test tree with the GPU's/etc).
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