Bug#931896: grub-efi-amd64: symbol `grub_file_filters` not found

[Colin Watson]

On Sun, Jul 14, 2019 at 11:56:39PM +0200, Diederik de Haas wrote:
> On zaterdag 13 juli 2019 09:05:44 CEST Sven Joachim wrote:
> > What I finally figured out after getting my system to boot again, is
> > that grub was still configured to install its core image to /dev/sda,
> > the old hard disk.  This configuration is apparently only stored in the
> > debconf database and nowhere else.
> 
> In the not too distant future, I'll remove that old drive (with WinXP on it) 
> from my system and my guess is that I then will have a problem.

That shouldn't be the case: we store the installation device using a
/dev/disk/by-id/ path, which isn't affected by removing other disks.

> Will 'dpkg-reconfigure grub' update the debconf database and thereby fix that 
> problem?

grub-pc not grub, but yes, that updates the debconf database.  (This is
not the same problem that the original reporter of this bug had; they
were using UEFI, not BIOS, which is generally less susceptible to this
class of problem although apparently they still managed to run into it.
In your case the bug is in whatever documentation advised you to simply
run grub-install when switching over to a new disk rather than
reconfiguring the system to make this persistent.)

> Storing that value in f.e. /etc/default/grub seems like a much more logical 
> place (to me).

In the abstract I can see that point, but I'm afraid that specific
location isn't possible since that file is used by a different layer of
the code.  At some point it would probably be a good idea to put the
configuration somewhere in /etc instead, although I'm sure people would
still miss it.

> I understand that this bug was closed as it was in my case indeed a 
> misconfiguration. Due to the closing of the bug, apt-listbugs didn't inform me 
> of a potential issue and it also didn't turn up when I started reportbug 
> myself to report the issue. I happened to see this bug by accident.
> Having the NEWS file inform me and others of this potential issue would've been 
> nice and probably prevents several similar bugs from being reported.

NEWS file entries document issues that relate to upgrading to specific
newer versions.  However, as I noted in my original closing message,
this isn't triggered by upgrading to any specific version, but rather
simply by upgrading or downgrading to *any* version with a different
interface between core image and modules.  While this happens to have
been somewhat stable for a while, it could in principle change as
frequently as every single package upload, so the NEWS file isn't a
suitable place to discuss it.

-- 
Colin Watson                                       [cjwatson at debian.org]