Change in coreboot[master]: cpu/amd/agesa/family15tn/model_15_init.c: create correct MTRR solution

[Michał Żygowski (Code Review)]

Attention is currently required from: Arthur Heymans, Angel Pons, Felix Held.
Michał Żygowski has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/53991 )

Change subject: cpu/amd/agesa/family15tn/model_15_init.c: create correct MTRR solution
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Patch Set 3:

(1 comment)

File src/cpu/amd/agesa/family15tn/model_15_init.c:

https://review.coreboot.org/c/coreboot/+/53991/comment/b6b1ecae_9b2435eb 
PS3, Line 39: execution
> > Yes, I probably meant AGESA, because I recall having a longer execution time of AmdInitLate. […]

I have no fam15tn platform to test so can't say. It definitely helps on fam16 binaryPI where the AGESA had to be accessed one more time before payload for AmdInitLate. Replicated the setup here as well in case one includes a larger payload than SeaBIOS. E.g. EDK2 UEFI payload depending on included features may have 700KB or more. In such case the speedup would be noticable I think.