Bug#1052690: grub2: post-install script overrides manual changes to GRUB_DISABLE_OS_PROBER
Sorry, I never tested whether the setting actually persists; I just
hoped that it would. But indeed it is not; I had to manually intervene
once again.
Jordi's analysis and patch look plausible to me. It might be slightly
better to compare "${GRUB_DISABLE_OS_PROBER}" to "true" instead of
"false" (swapping the branches of the conditional), since that's what
/etc/grub.d/30_os-prober does.
Thanks,
Bertram
Bug#1052690: grub2: post-install script overrides manual changes to GRUB_DISABLE_OS_PROBER
Hello all,
It seems that the debconf setting 'grub2/enable_os_prober' gets reset to
false every time the package is reconfigured, possibly as part of a
package upgrade or reinstallation. When one invokes 'dpkg-reconfigure
grub-efi-amd64' (or grub-pc etc.) the previously chosen answer to the
'enable_os_prober' query is forgotten and the preselected answer is now
'No'. When dpkg-reconfigure is run with the '-phigh' option this happens
silently and os-prober is once again disabled. The same occurs when
reinstalling or upgrading the corresponding grub package.
Additional information: It turns out that the post-install script
patches /etc/default/grub here:
Yes, but by the time this postinst script is executed, debconf will have
already been misconfigured and the 'db_get grub2/enable_os_prober'
command as seen on line 401 will receive a possibly incorrect 'false'.
The double negative used in the configuration is a bit confusing,
especially once you deal with a commented line (meaning its contents are
disabled) declaring that the variable that dictates whether or not to
disable a certain setting should be set to disabled. The package script
'config' warns the reader 'Watch for the inverted logic here', and
ironically this is where the bug is at. I have attached a patch that
will rectify this issue. For simplicity I decided to compare the config
variable GRUB_DISABLE_OS_PROBER from /etc/default/grub to 'false', i.e.
a value of exactly 'false' will set the 'grub2/enable_os_prober' debconf
setting to 'true' and all other contents will result in
'grub2/enable_os_prober = false'. One could possibly expand the check to
include 0, no, False, FALSE and whatnot, but that is ultimately up to
the maintainers and I wanted to keep things simple. With this patch
applied the previously chosen answer is remembered and a
(re)installation or reconfiguration no longer changes the setting. Also,
manually uncommenting the line with GRUB_DISABLE_OS_PROBER=false (as
mentioned in the package changelog) will now result in debconf properly
changing the 'grub2/enable_os_prober' setting to 'true' the next time it
is invoked, so on upgrades and such that line will no longer be
rewritten into something that disables os-prober. Changing it to
anything other than 'false' will result in 'grub2/enable_os_prober' to
be set to 'false', and consequently the line containing
GRUB_DISABLE_OS_PROBER=whatever in /etc/default/grub will get rewritten
to the default commented '#GRUB_DISABLE_OS_PROBER=false', which means
the setting will now default to 'true', as before.
--
Kind regards,
Jordi Bosveld
diff -ur grub2-2.12~rc1.orig/debian/config.in grub2-2.12~rc1/debian/config.in
--- grub2-2.12~rc1.orig/debian/config.in 2023-10-08 13:31:00.421268494 +0200
+++ grub2-2.12~rc1/debian/config.in 2023-10-08 13:31:49.889261283 +0200
@@ -60,7 +60,11 @@
fi
# Watch for the inverted logic here...
if [ "${GRUB_DISABLE_OS_PROBER+set}" = set ]; then
- db_set grub2/enable_os_prober "false"
+ if [ "${GRUB_DISABLE_OS_PROBER}" = "false" ]; then
+db_set grub2/enable_os_prober "true"
+ else
+db_set grub2/enable_os_prober "false"
+ fi
fi
case @PACKAGE@ in
Bug#1052690: grub2: post-install script overrides manual changes to GRUB_DISABLE_OS_PROBER
Agustin Martin wrote: > I have my 'local-settings.cfg' in that dir and works as expected. > > Does using '/etc/default/grub.d/99-osprober.cfg' work? That does work. As far as I can make out, the directory ships empty (though other packages may add stuff there), so it's hard to find out about that required extension. Not sure where that information belongs... ideas: - /etc/default/grub.d/README - /etc/default/grub - the `grub` texinfo document? That documents /etc/default/grub but not the /etc/default/grub.d override. But I haven't checked whether that's a grub feature or something added by Debian. Cheers, Bertram
Bug#1052690: grub2: post-install script overrides manual changes to GRUB_DISABLE_OS_PROBER
On Tue, Sep 26, 2023 at 09:38:22AM +0200, Bertram Felgenhauer wrote: > Package: grub2 > Version: 2.12~rc1-10 > > It's also worth noting that `update-grub` does not appear to pick up > files from `/etc/default/grub.d` so putting the setting there is > ineffective. (I put the setting into `/etc/default/grub.d/99-osprober` > and update-grub didn't pick it up in my test.) Hi, I have my 'local-settings.cfg' in that dir and works as expected. Does using '/etc/default/grub.d/99-osprober.cfg' work? Regards, -- Agustin
Bug#1052690: grub2: post-install script overrides manual changes to GRUB_DISABLE_OS_PROBER
Package: grub2 Version: 2.12~rc1-10 Dear Maintainer, * What led up to the situation? An update of grub a while ago changed the default os-prober behavior; see also #1038974. * What exactly did you do (or not do) that was effective (or ineffective)? I edited /etc/default/grub to reenable os-prober. * What was the outcome of this action? While at first effective, subsequent updates of grub reset the default each time. (It took me a while to realize this.) * What outcome did you expect instead? I expected the setting to stick when grub is updated. Additional information: It turns out that the post-install script patches /etc/default/grub here: https://git.launchpad.net/ubuntu/+source/grub2/tree/debian/postinst.in?h=debian/sid=f85ded33219dc350d3ef96caa9d1ce118247b086#n398 It's also worth noting that `update-grub` does not appear to pick up files from `/etc/default/grub.d` so putting the setting there is ineffective. (I put the setting into `/etc/default/grub.d/99-osprober` and update-grub didn't pick it up in my test.) The proper solution for now appears to be to run `dpkg-reconfigure grub-efi-amd64` (Would other grub packages work too? This is the package that owns the corresponding debconf setting `grub2/enable_os_prober` for me) Ideally, I'd prefer the manual edits to be recognized and kept. But at the very least, please add a comment in /etc/default/grub to point towards a reliable way of changing this setting. And maybe add a hint to the warning messages that update-grub prints about os-prober?
