On Fri, May 23, 2025 at 11:26:50AM +0100, Alireza Sanaee wrote:
> OS like Linux is using PPTT processor node's identical implementation
> flag [1] to infer whether the whole system or a certain CPU cluster is
> homogeneous or not [2]. QEMU currently only support building homogeneous
> system, set the flag to indicate the fact. Build a root node in PPTT for
> indicates the identical implementation which is needed for a
> multi-socket system. Update the related PPTT tables as well.
>
> [1] ACPI 6.5 Table 5.158: Processor Structure Flags
> [2]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/acpi/pptt.c?h=v6.11-rc1#n810
>
> History:
> * v4->v5: fixed a typo
>
> * v3->v4: PPTT rev to 2
>
> * v2->v3: rebase to 10
>
> Alireza Sanaee (2):
> hw/acpi/aml-build: Build a root node in the PPTT table
> tests: virt: Update expected ACPI tables for virt test
>
> Yicong Yang (2):
> tests: virt: Allow changes to PPTT test table
> hw/acpi/aml-build: Set identical implementation flag for PPTT
> processor nodes
>
> hw/acpi/aml-build.c | 24 +++++++++++++++---
> tests/data/acpi/aarch64/virt/PPTT | Bin 76 -> 96 bytes
> .../data/acpi/aarch64/virt/PPTT.acpihmatvirt | Bin 156 -> 176 bytes
> tests/data/acpi/aarch64/virt/PPTT.topology | Bin 336 -> 356 bytes
> 4 files changed, 20 insertions(+), 4 deletions(-)
This interacts weirdly with loongarch. I tried applying patches
on top of that, and on loongarch, I see:
-[0F0h 0240 004h] Flags (decoded below) : 00000000
+[0F0h 0240 004h] Flags (decoded below) : 0000000E
Physical package : 0
- ACPI Processor ID valid : 0
- Processor is a thread : 0
- Node is a leaf : 0
+ ACPI Processor ID valid : 1
+ Processor is a thread : 1
+ Node is a leaf : 1
Identical Implementation : 0
I'm sending a pull request later today. Once merged, pls
rebase on top of that, updating loongarch as appropriate
and repost copying relevant people.
Cc Bibo Mao for more insight.
> --
> 2.34.1
