Bug#666974: installs to /dev/sda when grub-installer/bootdev = /dev/sdb

[Faidon Liambotis <paravoid@debian.org>]

On Tue, Apr 03, 2012 at 11:24:25AM +1000, Vincent McIntyre wrote:
> When I specify in my preseeding file:
>   d-i partman-auto/disk                  string  /dev/sdb
>   d-i grub-installer/bootdev             string  /dev/sdb
> 
> grub-installer ignores me and installs to /dev/sda.
> partman-auto does the right thing.
> 
> In some cases this can result in an unbootable system.

Indeed, I've experienced this and can confirm the bug. It can also lead
in errors in the installation process: I had a preseeding configuration
in which sda should stay empty and the operating system should be
installed in an entirely different disk; grub-installer tried to install
grub on sda, but sda had no partioning table or MBR whatsoever, which
made it fail with an error.

I've read grub-installer's source though and realized I can work around
it if I set grub-installer/only_debian to false, as this skips directly
to step 2 which then obeys the preseeded bootdev properly.

Regards,
Faidon