grub-1.99 and btrfs-only

grub-1.99 and btrfs-only

[Chuck Burns]

I have a btrfs-only system, using grub2 (1.99), and have /boot on btrfs as 
well...

When I first boot, grub first complains it cannot find files, then apparently 
successfully finds them, loading the menu..

After I select the option I want, grub again complains of unable to find a file, 
and seconds later begins to properly boot..

This is my boot.cfg
---
set timeout=5

  insmod gpt
  insmod btrfs
  set root=(hd0,gpt3)
  search --no-floppy --fs-uuid --set a549b032-017c-4a96-ae28-5dffe61cff1d
if loadfont /boot/grub/unifont.pf2; then
   set gfxmode=1680x1050
   insmod gfxterm
   insmod vbe
   terminal_output gfxterm
fi

set menu_color_normal=cyan/black
set menu_color_highlight=black/cyan

menuentry "Linux 3.1.0" {
  insmod gpt
  insmod btrfs
  set root=(hd0,gpt3)
  search --no-floppy --fs-uuid --set a549b032-017c-4a96-ae28-5dffe61cff1d
  linux /boot/bzImage-3.1.0 root=/dev/sda3 rootfstype=btrfs
  initrd /boot/initframfs-3.1.0
  set gfxpayload=keep
}
set default=0
---

These are my current subvolumes:
# btrfs sub list /
ID 256 top level 5 path mainroot
ID 257 top level 5 path home

I have sub 256 set as default, and then home is mounted onto mainroot.

I'm assuming that since I have my boot inside that subvolume, that is why 
grub, at first, has issues locating the files, but then manages to find it.

My question is this: Is anyone aware of any grub.cfg magic I can use to 
specify a specific subvolume to look for /boot/grub ? my plan is to eventually 
move boot into it's -own- subvolume, and create more subvolumes for different 
distros.

Re: grub-1.99 and btrfs-only

[Phillip Susi]

On 11/5/2011 10:02 PM, Chuck Burns wrote:
> These are my current subvolumes:
> # btrfs sub list /
> ID 256 top level 5 path mainroot
> ID 257 top level 5 path home
>
> I have sub 256 set as default, and then home is mounted onto mainroot.

I advise against using set-default at all.  The setup Ubuntu seems to be 
going for ( and is working well for me so far ) creates two subvolumes 
under the default root, named @ and @home, and intended to be mounted in 
/ and /home respectively.  The /@ subvolume is then mounted as the root 
via rootflags=subvol=@ argument, and grub is configured to use 
/@/boot/grub as its prefix directory.

I'm still getting a "sparse file not allowed" error during boot, and 
have to press enter to continue though.  Still not tracked that one down.

Re: grub-1.99 and btrfs-only

[Arand Nash]

On 07/11/11 22:07, Phillip Susi wrote:
> (...)
> 
> I'm still getting a "sparse file not allowed" error during boot, and
> have to press enter to continue though.  Still not tracked that one down.

https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/736743

Missing feature in GRUB, see Colin Watson's comments in partucular.