On Oct 14, 2013, at 2:29 PM, Josef Bacik <jba...@fusionio.com> wrote:
> On Mon, Oct 14, 2013 at 02:23:58PM -0600, Chris Murphy wrote: >> >> On Oct 14, 2013, at 1:21 PM, Chris Murphy <li...@colorremedies.com> wrote: >> >>> When /boot is on btrfs, and the default subvolume is changed, it makes the >>> system unbootable. The basic configuration is subvolumes: boot, root, home, >>> on one btrfs volume single device. The installer doesn't change the default >>> subvolume, it remains ID 5. >>> >>> If I change the default subvolume and reboot, I get a grub rescue prompt. >>> This means core.img in the MBR gap was found, but >>> /boot/grub/i386-pc/normal.mod could not be found. What's interesting is, at >>> the grub rescue prompt, 'set' returns: >>> >>> prefix=(hd0,msdos1)/boot/grub2 >>> root=hd0,msdos1 >>> >>> This appears to be a full path name, so it should always start from top >>> level regardless of the set-default subvolume, correct? Yet it's behaving >>> relative to the default subvolume. If I use 'ls (hd0,msdos1)' I'm returned >>> the contents of the subvolume I've set as default, which explains why >>> bootability is broken. >> >> Looks like what I'm experiencing is unintended. If a developer or someone >> more knowledgable than me can respond to the questions on grub-devel@ it >> would be very helpful so this can get fixed. >> >> http://lists.gnu.org/archive/html/grub-devel/2013-10/msg00038.html >> > > All grub has to do is read the "default" dir item in the tree_root and then > get > the location out of that dir item and then use that root as the default root. > The kernel does it's own path walk to that root just for dentry sake, but I > imagine grub doesn't have to do that, they can just say "ok this is our root" > and carry on. Thanks. I might be reading the inquiry on grub-devel@ wrong but it seems that's what they're doing now. The idea is that the GRUB prefix path should be immutable, regardless of the user using 'btrfs subvol set-default' to some nested subvolume, so that the system is always bootable. Chris Murphy-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
