Hello
With the cross compiling tool chain, coreboot takes 1G. If you are a bit short on space, or if you want to save writes to your SSD, instead of having multiple copies of the coreboot source folder, I have found out overlayfs is very practical.
If you have done git clone in /opt/coreboot/src/, simply create 4 extra folders there: coreboot-normal coreboot-fallback coreboot-normal.upper coreboo-fallback.upper
The first 2 will contain a pseudo filesystem, the last 2 will contain the files that uniquely different between your versions
Then run:
mount -t overlayfs overlay -o lowerdir=/opt/coreboot/src/ coreboot,upperdir=/opt/coreboot/src/coreboot-normal.upper /opt/coreboot/src/coreboot-normal mount -t overlayfs overlay -o lowerdir=/opt/coreboot/src/ coreboot,upperdir=/opt/coreboot/src/coreboot-fallback.upper/ /opt/coreboot/src/coreboot-fallback
You can have as many as you want in parallel. Useful if you are testing a feature but want to alternate quickly without having to recompile the other branch
When you are done, umount your folders, you will see your changes are only in the .upper folder. The original folder will not be affected.
Charlotte