On 2026-01-04 13:21, D. Hugh Redelmeier via Talk wrote:

I don't really understand what isn't working.
GRUB, the bootloader, probably has no problem with this.

Am I right in assuming the problem is with grub2-install(8), the program 
that is supposed to install GRUB?  Or perhaps grubby(8).

Oops, I answered in the wrong thread. It's grub all right, to be exact, /etc/grub.d/30_os-prober. If I make it non-executable (chmod -x), then all GRUB distros install cleanly.

Too late though. I migrated 30+ years old Slackware to CachyOS.

I have to learn BTRFS way of doing backup. All I know at the moment is,
btrfs send ... | btrfs receive ...
where source and destination have to be read-only.

Okay, but the "source" is the system I'm running. How do I make it read-only and still have it running? Or, make a snapshot and back that up? Then, I have 2 snapshots, one at the source and another at the backup destination. More reading...

--William