I was having the same problem. The grub command save_env gives no error
messages, but it doesn't actually make any changes to the environment
block (/boot/grub/grubenv) as it should. I download the source package
(grub-pc-1.98-1ubuntu7) and poked around a bit.
>From disk/raid.c:
grub_raid_write (grub_disk_t disk __attribute ((unused)),
grub_disk_addr_t sector __attribute ((unused)),
grub_size_t size __attribute ((unused)),
const char *buf __attribute ((unused)))
{
return GRUB_ERR_NOT_IMPLEMENTED_YET;
}
And from disk/lvm.c:
grub_lvm_write (grub_disk_t disk __attribute ((unused)),
grub_disk_addr_t sector __attribute ((unused)),
grub_size_t size __attribute ((unused)),
const char *buf __attribute ((unused)))
{
return GRUB_ERR_NOT_IMPLEMENTED_YET;
}
I had my /boot on a LVM2 volume and it looks like the original reporter
(emteeyou) is using MD RAID (pure software RAID). I'm pretty sure this
is the cause of the problem. According to <a href="http://www.mail-
archive.com/[email protected]/msg13749.html">this message</a> there is
a good reason why GRUB2 won't write to LVM volumes and presumably the
same arguments apply to MD RAID.
Surprisingly, it DOES work with a BIOS-assisted software RAID (aka
"Fake" RAID). I created a 100MB non-LVM partition on my Fake RAID,
stuck /boot on it, and save_env now works correctly (grub-reboot does
too). I didn't read enough code to figure out why, but GRUB does not
load the "raid" module when I boot this configuration, so the above
function grub_raid_write could never be called.
So to sum things up: if you are having this problem, put /boot on a
normal partition that is not a MD RAID or LVM volume.
To close the bug, the documentation should be updated so users are
warned of GRUB's limited support for LVM and MD RAID. Basically,
GRUB_DEFAULT=saved will not work as expected with LVM or MD RAID.
Because this bug could have serious consequences for someone trying to
reboot a remote machine, grub-reboot should detect the problem and
refuse to work or at least print a warning I might try my hand at a
patch, but I can't think of a way to check if /boot is on LVM or MD RAID
using a bash script. Any hints?
--
grub-reboot doesn't work – prev_saved_entry doesn't get reset
https://bugs.launchpad.net/bugs/625475
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