On Jan 1, 2014, at 10:17 PM, Michael Chang <mch...@suse.com> wrote: > > We snapshot /boot for kernel and initrd, otherwise the rollback would > encounter problem of incompatible userland and kernel/kernel modules. > And we need the ability to rollback them in terms of usefulness.
Of course, understood. core.img is only going to point to one /boot, which may not be the /boot snapshot needed for the kernel and initrd. This will be really confusing for mortal users. They'd be unlikely to figure it out and understand it, without documentation. If core.img points to the "current" /boot, which it should, that boot has the accumulated knowledge of all snapshots, and any recently updated grub modules. Choosing to boot a snapshot means using a different /boot for kernel/initramfs than what grub is using for its root. I don't off hand see a problem with this because it's literally just two files that grub loads from a different boot subvolume, found with an absolute path to that snapshot. And it also uses rootflags=subvol= to use the matching root snapshot. A separate issue that's not grub's problem is how to deal with the (now wrong) fstab entries. systemd looks at fstab and generates mount jobs from that; if taught to understand it's booting a snapshot it could second guess parts of the fstab. Based on the name of the currently booting root snapshot, which systemd definitely knows, it could mount that subvol= instead of what's in fstab. It can use name substitution to do the same thing with the other subvolume-snapshots that match the root one. Meaning all of the snapshots for a system have the same base (re)naming convention. Chris Murphy _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
