I'm moving my system to a new SSD. And I would like to take this opportunity to convert from BIOS to EFI. Mainboard is about 1 year old, so firmware should be current enough to avoid the UEFI issues the early versions had.
I'm using two complete system partitions (for production and test) and the selection is done via GRUB menu. I would like to keep that.
The new SSD is GPT-partitioned, and I have created an "EFI System" partition with type EF00, VFat formatted, and mounted at /boot/efi.
However, now I'm caught in a vicious circle: As long I haven't installed an EFI-enabled GRUB on the new SSD, I need to keep the CSM module enabled in UEFI setup and boot from the old HDD in BIOS mode. But as long as I boot in BIOS mode, I can't do a
grub-install --target=x86_64-efi because it says
EFI variables are not supported on this system.
I've found some instructions for Ubuntu referring to
boot-repair, but that's not available for Arch Linux and there is some dispute if it's a good idea to use it at all.