Let's make our units more robust to being added to an initrd:
1. systemd-boot-update only makes sense if sd-boot is available in /usr/
to copy into the ESP. This is generally not the case in initrds, and
even if it was, we shouldn't update the ESP from the initrd, but from
the host instead.
2. The rfkill services save/restore rfkill state, but that information
is only available once /var/ is mounted, which generally happens
after the initrd transition.
3. utmp management is partly in /var/, and legacy anyway, hence don't
bother with it in the initrd.
No functional change, just a cleanup to make the subsequent changes easier to
see. This is a continuation of 9810e41942
> The block is reordered and split to have:
> 1. description + documentation
> 2. (optionally) conditions
> 3. all the dependencies
The dependencies for shutdown.target are listed separately because they are the
other deps are for startup, and shutdown.target only matter much later.
This renames systemd-boot-system-token.service to
systemd-boot-random-seed.service and conditions it less strictly.
Previously, the job of the service was to write a "system token" EFI
variable if it was missing. It called "bootctl --graceful random-seed"
for that. With this change we condition it more liberally: instead of
calling it only when the "system token" EFI variable isn't set, we call
it whenever a boot loader interface compatible boot loader is used. This
means, previously it was invoked on the first boot only: now it is
invoked at every boot.
This doesn#t change the command that is invoked. That's because
previously already the "bootctl --graceful random-seed" did two things:
set the system token if not set yet *and* refresh the random seed in the
ESP. Previousy we put the focus on the former, now we shift the focus to
the latter.
With this simple change we can replace the logic
f913c784ad added, but from a service that
can run much later and doesn't keep the ESP pinned.
Boot loaders are software like any other, and hence muse be updated in
regular intervals. Let's add a simple (optional) service that updates
sd-boot automatically from the host if it is found installed but
out-of-date in the ESP.
Note that traditional distros probably should invoke "bootctl update"
directly from the package scripts whenver they update the sd-boot
package. This new service is primarily intended for image-based update
systems, i.e. where the rootfs or /usr are atomically updated in A/B
style and where the current boot loader should be synced into the ESP
from the currently booted image every now and then. It can also act as
safety net if the packaging scripts in classic systems are't doing the
bootctl update stuff themselves.
Since updating boot loaders mit be a tiny bit risky (even though we try
really hard to make them robust, by fsck'ing the ESP and mounting it only on
demand, by doing updates mostly as single file updates and by fsync()ing
heavily) this is an optional feature, i.e. subject to "systemctl
enable". However, since it's the right thing to do I think, it's enabled
by default via the preset logic.
Note that the updating logic is implemented gracefully: i.e. it's a NOP
if the boot loader is already new enough, or was never installed.
