Bug#497791: Bug #497791, confirmation

[Adolf Winterer]

Am Tuesday 28 July 2009 09:54:23 schrieb Felix Zielcke:
> Am Dienstag, den 28.07.2009, 09:44 +0200 schrieb Adolf Winterer:
> > Am Monday 27 July 2009 16:25:29 schrieb Felix Zielcke:
> > > Am Montag, den 27.07.2009, 15:26 +0200 schrieb Adolf Winterer:
> > > > Hi,
> > > >
> > > > I can confirm the problem. This is the sequence that leads to the
> > > > problem:
> > > >
> > > > * Install Lenny 5.0.2
> > > > This will automatically use grub2, the system is perfectly bootable.
> > > >
> > > > * Add Squeeze to the sources.list
> > > > After updating the package list the packages grub-common and grub-pc
> > > > are shown as updateable.
> > > >
> > > > * Update grub-common and grub-pc
> > > > During the update a requestor shows up in the terminal window of
> > > > Synaptic asking for the device to install grub into. Here it is
> > > > /dev/sda3. The
> > >
> > > You probable mean /dev/sda. We don't ask for partitions.
> >
> > I must have misread the prompt then. On the other hand, grub is _not_
> > installed in the MBR of the device (where rEFIt resides), but in the
> > partition /dev/sda3. How could the procedure work correctly if /dev/sda
> > is specified.
>
> It can't. If you want to have grub in a bootsector of a partition
> instead of MBR you currently have to run grub-install /dev/sda3
> yourself.

Yesterday I installed another system (MacBookPro5,2) from scratch (base 
install "Lenny") and updated all packages _except_ grub-pc and grub-common 
to "Testing". Today I bootet up and performed the update on these two 
packages only, no other action. 

This time I got a graphical prompt from Synaptic, it offered a checkbox 
(default was "unchecked", I left it in this state as I need GRUB in a 
partition) for installation of GRUB into "/dev/sda". The prompt specifically 
asked for a _device_, being much clearer than the textual version AFAIR.

The difference in the type of the prompting used (textual vs. graphical) seems 
to come from the order in which the packages were updated. The Synaptic 
package was updated this time _before_ the GRUB packages.

As expected the system did not boot up, producing the error again, which could 
be overcome by the (now known) trick, replacing the line with "search.." with 
a line saying 'insmod "linux"' in the grub editor.

After the reboot all I did was issuing "grub-install /dev/sda3" and shutting 
down the system again. The system startet without any problem then.

This clearly shows that the _only_ problem is the 
missing "grub-install /dev/sda3" for a GRUB installation in a partition. The 
usage of UUIDs is definitely not an issue.

> > > I just installed now lenny in a vm, upgraded grub-pc and grub-common to
> > > squeeze and selected /dev/sda and rebooted. Worked fine.
> >
> > What was your partitition layout? Was grub in the MBR of the device?
>
> Yes grub was in MBR. There was only one partition on the disk.

This makes the difference then.

> > > Then I did dpkg-reconfigure grub-pc to remove the selections of
> > > /dev/sda and tried the same.
> > > And it failed with unknown command initrd.
> > > Replacing the root=UUID with root=/dev/sda1 didn't help.
> > >
> > > Well anyway it's a bug we already fixed and that's why we implemented
> > > the debconf prompt now.
> >
> > Hmm, but I had the problem. Could it be possible this only occurs, if
> > grub does not reside in the MBR?
>
> Yes

See above.

> > > Are you sure that /dev/sda was seletected the 2nd time you were asked?
> >
> > There was no selection by option list, it was a prompt that asked for a
> > string, anything could have been entered.
>
> Do you confuse this maybe with the kopt migration dialog from menu.lst?

I know this kind of problem from another case. But on this installation there 
is not /boot/grub/menu.lst. And, the problem was fixed by issuing the 
grub-install command.

> In another report somebody already wished to enter a device manually.
> But AFAIK debconf doestn't support it in one prompt to have a multiple
> choice and can enter a device yourself, so we'd need to add a 2nd one
> which I don't really like.

Suggestion:
If you do not want to add an additional prompt, then please add a text on the 
screen showing the check box, clearly stating something like this:
"If grub is NOT installed in the MBR on this computer, then you need to enter 
the command 'grub-install /dev/XdYn' from a root shell. Caution: Not doing so 
will leave your computer in an unbootable state."

> > > > * Permanent solution
> > > > Something is wrong with using UUIDs in connection with booting,
> > > > because uncommenting the according line in /etc/defaults/grub:
> > > > GRUB_DISABLE_LINUX_UUID=true
> > > > and running update-grub changes the file /boot/grub/grub.cfg. The
> > > > line with "search ... --fsuid ..." is still present, but the line
> > > > with "linux ..." has changed to reflect /dev/sda3 as boot device.
> > > >
> > > > Therefore the presence of the line containing "search ..." or the
> > > > length of the line do not seem to be a problem, but using the UUID
> > > > is.
> > >
> > > That's maybe for you a solution. But the real solution is to make sure
> > > that grub-install gets run when the package gets upgraded, so you won't
> > > be affected by other bugs in the parser etc.
> > > For example there were now in the squeeze version a few parser bug
> > > fixes, though they didn't affect the default generated config.
> >
> > I will issue a manual grub-install before reboot with the next
> > installation and report back.
> >
> > Thank you for supporting me.
>
> Thanks for replying fast :)

Again, thank you for your support. I have a much better understanding of the 
issue now.