This problem reared its ugly head again. I decided, using Debian 12, to
add in the swap space used by Debian 13 temporarily. After I had
finished I recreated the swap space from debian 13 and updated the swap
in fstab and resume in /etc/initramfs-tools/conf.d/resume,
update-initramfs -u, on Debian 13. But they did not take effect because
I was using grub from Debian 12. So I re-installed grub from Debian 13,
and the changes took effect, but that meant I was using the wrong grub.
This is a solution of sorts: to add a 40_custom entry to both systems:
menuentry "Boot Debian 12 GRUB" {
search --set=root --fs-uuid b1edc363-c5a4-4a37-ac23-6fd31ad5d1a8
configfile ($root)/boot/grub/grub.cfg
}
menuentry "Boot Debian 13 GRUB" {
search --set=root --fs-uuid 7d5ab11e-e07b-4456-b31c-b13c1e0b7a8d
configfile ($root)/boot/grub/grub.cfg
}
This allows either grub to boot the other grub. But it makes me wonder
why grub isn't independent of the OS which installed it? Particularly
sudo update-initramfs -u won't have any effect if the OS is booted from
a different OS's grub.
