[M] Change in coreboot[main]: arch/arm64: Add EL1/EL2/EL3 support for arm64

[Julius Werner (Code Review)]

Julius Werner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/74798?usp=email )

Change subject: arch/arm64: Add EL1/EL2/EL3 support for arm64
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Patch Set 19:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/74798/comment/d283396e_5e8d93b6 :
PS5, Line 11: one boots into TF-A first and drops into EL2 for coreboot afterwards.
> not treated as a decision to support upstream to run a proprietary BIOS under coreboot (i.e. proprietary BL31).

FWIW I don't think we're currently disallowing proprietary BL31s to begin with? That's what CONFIG_ARM64_BL31_EXTERNAL_FILE was made for. I would agree that there may be a new discussion to be had in case someone's proprietary BL31 requires a lot of custom support code to be added to coreboot, but as long as they support the same interface and just want to put their own file into CBFS I don't think we need to take issue with that (it's also pretty impossible to prevent in practice, anyone can run cbfstool manually).