[coreboot] using overlayfs to have several coreboot dev envs

Patrick Georgi pgeorgi at google.com
Mon Nov 14 08:21:50 CET 2016

A more portable solution to the "big toolchain" problem is to store
the toolchain outside the coreboot tree. Something like

$ util/crossgcc/buildgcc -D $HOME/.xgcc

Then add $HOME/.xgcc/bin to your PATH.


2016-11-13 21:34 GMT+01:00 Charlotte Plusplus <pluspluscharlotte at gmail.com>:
> 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
> --
> coreboot mailing list: coreboot at coreboot.org
> https://www.coreboot.org/mailman/listinfo/coreboot

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