[S] Change in coreboot[main]: soc/intel/common/block/cpu: Add Kconfig for effective way size for NEM+

[Subrata Banik (Code Review)]

Attention is currently required from: Ashish Kumar Mishra, Jérémy Compostella, Paul Menzel, Sowmya Aralguppe, Wonkyu Kim.

Subrata Banik has posted comments on this change by Jérémy Compostella. ( https://review.coreboot.org/c/coreboot/+/83946?usp=email )

Change subject: soc/intel/common/block/cpu: Add Kconfig for effective way size for NEM+
......................................................................

Patch Set 13:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/83946/comment/a62e1973_8dc3a9cb?usp... :
PS13, Line 23: The issue addressed by this commit can be observed with the following
             : experiment: using a 18 MB LLC SKU, set `DCACHE_RAM_SIZE` to
             : 0x400000 (4 MB).
> > This isn't a real issue, it's just a hypothesis that CONFIG_DCACHE_RAM_SIZE is larger than the way size.
>
> The coreboot enhanced NEM code allows `CONFIG_DCACHE_RAM_SIZE` requiring multiple ways but it violate the Alder Lake, Meteor Lake and Panther Lake specification if such a configuration is used ⇒ the code is wrong and this is the issue these CL are addressing. These CL address a coreboot Intel eNEM code issue not a Google board issue.
>
> If you believe that  `CONFIG_DCACHE_RAM_SIZE` should never be larger than the effective way size, then why does the bootblock eNEM support multiple ways ? And why is violating the specification by not considering the effective way size ?
>
> If you refuse the code to be fixed arguing that no configuration is taking advantage of it, please implement a mechanism in bootblock limiting the configuration to one **effective** way and remove the support for multiple ways. My only objective here is to fix code that does not comply with the specification and I was able to verify the code does not work by tweaking the configuration. *I tweaked the configuration, not the code*.
>
> My experiments demonstrated that 4MB works like a charm only with these two CLs.

I will get back to you by next week early.