systemd 254 With New Soft Reboots Feature, systemd-battery-check

[Mario Junior]

- The systemd kernel-install script has been rewritten in C.

No rust? It's a miracle!

[discordian]

Can someone tell me what the use case for a soft reboot is? When is it really useful ovee just hard rebooting?

Testing an A/B update before it gets "committed" to the bootloader.

[EphemeralEft]

Does anyone know if the "soft-reboot" requires locally re-entering the password for CryptSetup devices?

[Jelgnum]

Soft reboot is a really cool feature, I'll have to try it out, some updates just don't need a full reboot

[waxhead]

How is soft reboot different than starting the rescue target and then going back to multi user target again?

(In the old days this would have been init 1 to bring the system to runlevel 1 and then back to something higher..)

Does the soft reboot active something different?!

[cynic]

Can someone tell me what the use case for a soft reboot is? When is it really useful ovee just hard rebooting?

for example you could use it to test if your custom services are correctly configured.

[zbyszek]

How is soft reboot different than starting the rescue target and then going back to multi user target again?

(In the old days this would have been init 1 to bring the system to runlevel 1 and then back to something higher..)

In soft reboot, all of userspace is brought down and no process survives (*). PID1 shuts all services down like during normal shutdown, and then reexecs itself, so new code and configuration is active, and then restarts all services like during normal boot. In the traditional "runlevel 1", many things would be shut down, but not everything, and then when going back to a higher runlevel, things would just be added.

(*) The discussion/disagreement upstream was about exceptions to this. For the next release, some mechanism how to let *some* services survive soft reboot will be added. But people have different ideas how to do this, so for now there is no exception mechanism. (At the unit level. For individual processes there's the same exception mechanism that is used for the initrd transition to allow root storage daemons to persist. But let's ignore this detail )

[zbyszek]

Does anyone know if the "soft-reboot" requires locally re-entering the password for CryptSetup devices?

For the root device: no. The system is running from the mounted device, so it cannot go away, so the crypt block device must survive the reboot.

For other devices: possibly. They could be unmounted/closed during the "shutdown", depending on the configuration.

[zbyszek]

No rust? It's a miracle!

kernel-install was rewritten to use the huge set of helpers used by other code. Since that code is already in C, there wasn't much choice. There are plans to start using Rust in systemd, but most likely for more "leaf" things.