This is another attempt to avoid having duplicated menu entries caused by
GRUB having support to parse BLS snippets and the 15_ostree script adding
menu entries as well.
The previous attempt was in commit 985a141002 ("grub2: Exit gracefully if
the configuration has BLS enabled") but that lead to users not having menu
entries at all, due having an old GRUB version that was not able to parse
the BLS snippets.
This happened because the GRUB bootloader is never updated in the ESP as
a part of the OSTree upgrade transaction.
The logic is similar to the previous commit, the 15_ostree script exits if
able to determine that the bootloader can parse the BLS snippets directly.
But this time it will not only check that a BLS configuration was enabled,
but also that a /boot/grub2/.grub2-blscfg-supported file exists. This file
has to be created by a component outside of OSTree that also takes care of
updating GRUB to a version that has proper BLS support.
This reverts commit 985a141002.
It turned out that some people have old bootloaders, and hence
get the "no entries" problem. That's much, much much worse
than double entries.
Since Fedora 30 grub2 has support to populate its menu entries from the
BootLoaderSpec fragments in /boot/loader/entries, so there's no need to
generate menu entries anymore using the /etc/grub.d/15_ostree script.
But since ostree doesn't update the bootloader, it may be that the grub2
installed is an old one that doesn't have BLS support.
For new installs, GRUB_ENABLE_BLSCFG=true is set in /etc/default/grub to
tell the /etc/grub.d/10_linux script if a blscfg command has to be added
to the generated grub2 config file.
So check if BLS is enabled in /etc/default/grub and only add the entries
if that's not the case. Otherwise the menu entries will be duplicated.
The approach has the drawback that if a user sets GRUB_ENABLE_BLSCFG=true
in /etc/default/grub without updating grub2, they will get an empty menu.
Since there won't be any entries created by the 30_ostree script and the
blscfg command won't work on the older grub2.
Unfortunately there is no way to know if the installed grub2 already has
BLS support or not.
Related: https://bugzilla.redhat.com/show_bug.cgi?id=1751272#c27Closes: #1929
Approved by: jlebon
Apparently there testing systems that literally install *all*
packages. Having `ostree-grub2` currently causes grub2 to fail
on a non-ostree managed system. Let's just gracefully exit
if there's no system repository.
https://bugzilla.redhat.com/show_bug.cgi?id=1532668Closes: #1399
Approved by: jlebon
ostree-grub-generator can be used to customize
the generated grub.cfg file. Compile time
decision ostree-grub-generator vs grub2-mkconfig
can be overwritten with the OSTREE_GRUB2_EXEC
envvar - useful for auto tests and OS installers.
Why this alternative approach:
1) The current approach is less flexible than using a
custom 'ostree-grub-generator' script. Each system can
adjust this script for its needs, instead of using the
hardcoded values from ostree-bootloader-grub2.c.
2) Too much overhead on embedded to generate grub.cfg
via /etc/grub.d/ configuration files. It is still
possible to do so, even with this patch applied.
No need to install grub2 package on a target device.
3) The grub2-mkconfig code path has other issues:
https://bugzilla.gnome.org/show_bug.cgi?id=761180
Task: https://bugzilla.gnome.org/show_bug.cgi?id=762220Closes: #228
Approved by: cgwalters
Javier Martinez Canillas
Colin Walters
Gatis Paeglis