On Mon, Nov 21, 2022 at 3:53 PM Zbigniew Jędrzejewski-Szmek
> == Summary ==
> By design, ostree does not manage bootloader updates as they can not
> (yet) happen in a transactional, atomic and safe fashion. Thus bootupd
) was created to solve this issue
> and enable admin-lead bootloader updates. This change is about
> enabling bootupd integration in Fedora Silverblue and Fedora Kinoite
> to make bootloader updates easier.
This change does strikes me as something that shouldn't be necessary.
The boot loader needs to updated, this is pretty clear, but I think we should
have the technology to just update the boot loader in atomic (*) fashion without
involving the admin.
In particular, two reasons why an upgrade might be interrupted were raised:
power being cut and the system crashing. Bootupd (or any other daemon) cannot
do much about crashes so this isn't a good motivation. For power, we have
partial solutions: software-initited poweroffs or reboots should be delayed by
systemd inhibitors. Similarly, when on battery, the upgrade could be delayed if
battery power is below some fraction. The only case that we really need to
worry about is the user unplugging the power cord or pressing a button for force
a hard poweroff or reboot. But I think it should be enough to just pop up a
notification message: "critical system update in progress, do not reboot or
power-off" for the duration.
Bootupd+bootupctl creates a lot of interface for the admin
(status, update, adopt-and-update, validate). This is additional stuff
to learn. It is also additional logic to implement: bootupd must understand
EFI and boot partitions, mount points, what to do during upgrades, etc.
I took a brief look at the code and it makes various assumptions about
how the partitions are named (instead of using part-type uuids!),
that ESP is mounted on /boot/efi, etc. I think this will be problematic
in the long term because it hardcodes assumptions about the system
and duplicates logic that is already implemented in other places.
Also, bootupd does up-calls into the package manager to query state.
Information should flow from the package management system into lower-level
components, and not the other way around. The package management system
should just call into lower-level helpers with specific component
paths and versions to upgrade, and those components shouldn't ever need
to look at the big picture. Mixing the paradigms results in fragility.
The raison d'être for bootupd seems to be updates of grub. I guess there isn't
much that can be done in the short term: grub doesn't provide a way to do
updates atomically, and we need to do those updates, and bootupd seems to be a
reasonable interim solution to wrap them. But I hope this will stop being
necessary, and either grub will provide such functionality and/or we'll use a
different bootloader. In other words, I understand and won't block this Change,
but doesn't make me particularly happy. It seems that it's code that will be
used for some time and then go away.
We could do the same thing SUSE does and switch to calling
scripts/tools to install into /boot and /boot/efi rather than doing it
directly from RPM. That would simplify the logic of bootupd and allow
it to just call these tools instead of having to go back and forth
between the package manager and the system environment.
真実はいつも一つ！/ Always, there's only one truth!