[coreboot-gerrit] [L] Change in coreboot[main]: acpi: Add PPTT support

[Arthur Heymans (Code Review)]

Attention is currently required from: Cliff Huang, David Milosevic, Lance Zhao, Martin L Roth, Maximilian Brune, Nico Huber, Patrick Rudolph, Tim Wawrzynczak.

Arthur Heymans has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/78071?usp=email )

Change subject: acpi: Add PPTT support
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Patch Set 18:

(1 comment)

File src/acpi/acpi_pptt.c:

https://review.coreboot.org/c/coreboot/+/78071/comment/25668f74_6dabf687 :
PS17, Line 131: cache_reference_t cache_refs[CONFIG_ACPI_PPTT_MAX_CACHES];
> I decided against it, since it is harder to restrict the array size then. We would have to limit the array size based on the number of CPUs times the number of caches per CPU. This would then eat the stack because of recursion. Basically, MAX_CPUS*MAX_CACHES_PER_CPU*(16 bytes for the struct)*MAX_DEPTH_OF_TREE.

That should not be the case. In a typical setup all CPUs have the same caches. So this would be the number of different caches in the system. In that case each CPU points to the same cache pointer and you don't need a large array.