[M] Change in coreboot[master]: build: List all Kconfigs in CBFS `config` file, compress it

[Julius Werner (Code Review)]

Julius Werner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/69710 )

Change subject: build: List all Kconfigs in CBFS `config` file, compress it
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Patch Set 3:

(1 comment)

Patchset:

PS3:
> Technically, the new use case was already possible, just needed additional steps.

Well, it's only possible when you have access to the original coreboot source tree that the image was built with. That isn't always the case. My goal was to make it possible to tell the state of any option if you just have the image and nothing else. (In this instance our goal is to make futility able to tell whether certain verification options like CONFIG_VBOOT_CBFS_INTEGRATION are set so it can pick the appropriate strategy when re-signing an image with different keys.)
> With the fixed, new solution, if one wants to see which options differ from defaults (a common case when providing user support), one has to run make olddefconfig && make savedefconfig .

I fixed this now with the second patch set in CB:69955. It puts the savedefconfig options first in the file, then a comment saying that that part ends there, and then the other (automatic) options below that. That way you can easily get the minimal defconfig back by just cutting off everything below that comment. I hope that's a compromise that makes all our use cases work?