Make UEFI variables stored outside of RPI_EFI.fd

[sharpenedblade]

When I update, it makes all configuration be lost, this is very concerning on headless servers because the uefi interface cannot be assessed. If it is stored in a separate file, for example RPI_EFI_VARS.fd then it can be excluded from an update, by package managers or manually.

[jlinton]

See if https://github.com/jlinton/edk2-platforms/blob/cppc6-various-fixes-vc4aml-mailboxspinlock-xhcipci-clocktweaks-spiv4/RPI_EFI.fd fixes your problem.

[rgl]

Any update on this?

Having the variables in another file also opens the door for using https://gitlab.com/kraxel/virt-firmware to manipulate the VARS file without the need to boot a RPi, as it can be manipulated in another machine before writing it into the final sdcard.

PS this is related with #6, #102, #138, and virt-firmware #6.

PPS in the mean time virt-firmware #6 was implemented, so we can now set variables like in rgl/rpi4-uefi-ipxe@2a85b3d.