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:

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