[systemd-devel] GNOME boot-complete.target integration ?

[Lennart Poettering]

On Mo, 29.06.20 11:02, Hans de Goede (hdegoede at redhat.com) wrote:

> Hi All,
>
> For Fedora 33 I would like to get rid of some ugly hacks we have
> wrt the grub-hidden-menu feature Fedora has been shipping for a
> while now.
>
> One part of this will be setting SYSTEMD_REBOOT_TO_BOOT_LOADER_ENTRY
> in logind's environment, and add /run/systemd/reboot-to-boot-loader-menu
> support to the Fedora grub-packages (the hidden-boot-menu stuff is
> not in upstream grub yet) and make GNOME use the dbus protocol to
> request rebooting into the boot menu.
>
> Another, harder part is boot-success or in systemd terms boot-complete
> support. ATM the Fedora GNOME packages contain a downstream patch
> which directly invokes "grub2-set-bootflag boot success". The plan
> is to have a grub2-bless-boot.service which will be a copy of
> systemd-bless-boot.service which will do grub's equivalent of
> calling /usr/lib/systemd/systemd-bless-boot good  (we do not
> want automatic-boot-assesment, we just want the menu to show or
> not show on the next boot). This bit is east too.
>
> The tricky part is having grub2-bless-boot.service not run until
> GNOME says that it is ok. The thinking behind this (and current
> behavior) is that even if everything looks ok from the all services
> are running pov, then things might still be wrong. E.g. the kbd
> and mouse could be non-functional leaving the user with a
> non-functional system. So we only want to mark the boot successful
> after:
>
> 1. The user has logged in successfully and the session lasts
> at least 2 minutes (could be a bit shorter, we want to catch the
> case where the session immediately exits / crashes after login); or
>
> 2. The user selects reboot/shutdown from the GNOME system-control
> menu.
>
> In both these cases we want to block the boot-complete.target
> from being considered finished/ready until GNOME says it is.
>
> I can easily achieve this by not adding the grub2-bless-boot.service
> to any targets, and then manually starting it (with a polkit rule to
> allow a regular user to do this) when either condition becomes true,
> but then I still have the GNOME code doing something grub (Fedora's
> grub even) specific. So what I really want to do is delay the
> the boot-complete.target from being considered finished/ready until
> GNOME says it is.
>
> So the question really is, is there a way to have a unit wait with
> starting until a certain event happens?
>
> I guess I could use a Oneshot type service and have a little helper app
> which waits until it is signalled that the boot is complete? Any other
> ideas?

Why not have a tiny service that is started as part of boot. It hangs
around for 2min or, and then exits with failure. If however it is
contacted by D-Bus before that it exist immediately with
success. Then, make GNOME just ping that service if all is good.

The service would then become part of the usual boot process, ordered
before the boot blessing.

Wouldn#t that suffice?

Lennart

--
Lennart Poettering, Berlin