[coreboot-gerrit] [XL] Change in coreboot[main]: vc/intel/fsp/mtl: Add x86_64 FSP headers

[Subrata Banik (Code Review)]

Attention is currently required from: Appukuttan V K, Dinesh Gehlot, Eran Mitrani, Jakub Czapiga, Kapil Porwal, Tarun.

Subrata Banik has posted comments on this change by Appukuttan V K. ( https://review.coreboot.org/c/coreboot/+/82473?usp=email )

Change subject: vc/intel/fsp/mtl: Add x86_64 FSP headers
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Patch Set 5:

(1 comment)

File src/soc/intel/meteorlake/Kconfig:

https://review.coreboot.org/c/coreboot/+/82473/comment/8028a13c_fbcfc29a?usp... :
PS5, Line 350: PLATFORM_USES_FSP2_4
`PLATFORM_USES_FSP2_4` value for both 32-bit and 64-bit MTL FSP hence, selecting this forbid us to switch to 32-bit FSP seamlessly. Ideally we wish to keep MTL/Rex build support for 32-bit and 64-bit in parallel for scoping the performance impact.

Ideally you wish to use different FSP stream for 64-bit support as MTL-FSP doesn't officially support 64-bit FSP.

how about below code change
```
config FSP_HEADER_PATH
    string "Location of FSP headers"
    default "src/vendorcode/intel/fsp/fsp2_0/meteorlake/x86_64/" if HAVE_X86_64_SUPPORT
    default "src/vendorcode/intel/fsp/fsp2_0/meteorlake/x86_32/"
```