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

[David Milosevic (Code Review)]

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

David Milosevic 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 19:

(2 comments)

File src/acpi/acpi_pptt.c:

https://review.coreboot.org/c/coreboot/+/78071/comment/42d69a21_ca96631c :
PS17, Line 131: cache_reference_t cache_refs[CONFIG_ACPI_PPTT_MAX_CACHES];
Our current platform code makes sure to point to the same `struct pptt_cache` object whenever two caches share the same `next_level`. For instance, for the qemu-sbsa board we have this

```
/*
 * L2 cache (LLC)
 */
struct pptt_cache l2 = {

.next_level = NULL
};

/*
 * L1I cache
 */
struct pptt_cache l1i = {

.next_level = &l2
};

/*
 * L1D cache
 */
struct pptt_cache l1d = {

.next_level = &l2
};

/*
 * private resources of a cpu core. Same for
 * each core.
 */
struct pptt_cpu_resources core_resources = {

.cache = &l1i,

.next  = &(struct pptt_cpu_resources) {

.cache = &l1d,
    	.next  = NULL
    }
};
```

I think we can leave it for the platform code. I dont see a relevant advantage from deduplicating caches within the ACPI generation code.

Maybe we could add a small note for the user, that the PPTT code is sensitive to the pointers you pass in.
> Is this not more appropriate to declare this in setup_topology so that all siblings can reuse it? Now you create these references for each call of new_pptt_cpu. return reference_for_cache in pptt_cache if !0?

I have moved the cache list to `setup_topology`, so this is done. Keeping the discussion open though, in case someone wants reply. Otherwise feel free to mark as done.

File src/include/acpi/acpi.h:

https://review.coreboot.org/c/coreboot/+/78071/comment/a43fdcbc_52a3816c :
PS3, Line 1442: structures
> Nothing on my end, but this is not my thread ;)

Okay, then I think we can close this.