Change in ...coreboot[master]: soc/intel/basecode: Add support for updating ucode loaded via FIT

[Patrick Georgi (Code Review)]

Patrick Georgi has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/27369 )

Change subject: soc/intel/basecode: Add support for updating ucode loaded via FIT
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Patch Set 38:
> Patch Set 36:
> I do understand the process in this change. Let me elaborate
> my theory more accurately. You can have a RO FIT with entries
> to both RO MCU and RW MCU (at least that is what I understood
> earlier). Booting with the process of this change and top-swap
> disabled should have the same effect as booting with such a
> two-entry FIT and erased RW MCU. Right?

It's a design goal in Chromebooks that stuff like recovery mode remains predictable (ie. rely on read-only data _only_), while still allowing features like dev mode. (There's also the option of disabling write protect, but that's a whole different story.)

The top-swap solution provides this feature under these constraints even for FIT-based ucode updates. Your proposal requires erasing a block in RW even though it might not be "ours" anymore, but managed by the device owner (eg. in dev mode).