Bug#591416: This bug might be due to Windows programs overwriting grub

[Svante Signell]

On Tue, 2010-08-31 at 18:48 +0100, Colin Watson wrote:
> On Tue, Aug 31, 2010 at 05:27:59PM +0200, Svante R Signell wrote:
> > As revealed lately booting to Windows can cause parts of grub
> > overwritten by Windows programs.
> > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=550702
> > https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/441941
> > 
> > I think this happened to me after a Windows XP session. I didn't react
> > too much then, since grub booted into Linux and then grub-pc was
> > upgraded by a new version. Missing boot menu might be due to some
> > program overwriting the "embedding area". Now I'm reluctant to boot to
> > Windows until this problem is solved. The problems seen are similar as
> > the Ubuntu bug:
> > https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/601563 where no
> > boot menu is shown at all, but Linux boots automatically.
> > 
> > Pleas let me know if I can help in any way to find which program is
> > overwriting grub.
> 
> Can you provide the specific data I requested in my blog post?  Namely:
> 
>  * Save the output of 'fdisk -lu' to a file.  In this output, take note
>    of the start sector of the first partition (usually 63, but might
>    also be 2048 on recent installations, or occasionally something
>    else).  If this is something other than 63, then replace 63 in the
>    following items with your number.

No problem to do this!

>  * Save the contents of the embedding area to a file (replace '/dev/sda'
>    with your disk device if it's something else): 'dd if=/dev/sda
>    of=sda.1 count=63'

Same here.

>  * Do whatever you do to make GRUB unbootable (presumably starting
>    Windows), then boot into a recovery environment.  Before you
>    reinstall GRUB, save the new contents of the embedding area to a
>    different file: 'dd if=/dev/sda of=sda.2 count=63'

Here I will potentially get into problems. In case grub won't boot I
need a Netboot or complete CD to recover grub. When running the Debian
installation CDs even choosing recovery gives you a lot of choices
before getting into a shell. Which CD to burn when running unstable? Is
it written somewhere how to reach the recovery shell. What to do then:
grub-install and update-grub2? What about install-mbr? 

>  * Follow up with these three files (the output of 'fdisk -lu', and the
>    embedding area before and after making GRUB unbootable).

Will do all the above when I know I can reinstall grub without problems.

> Thanks,
>