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The Wikipedia page on Devuan says it includes

... local modifications made only when needed to allow for other init systems rather than systemd. Modified packages include policykit and udisks. Devuan is supposed to work very similarly to the corresponding Debian release.

So, each Devuan release is a modified Debian release. My question is - what are these differences, in broad strokes? And more specifically:

• What are the main non-systemd software components that need to be executed instead of systemd running?


• Which packages does Debuan need to add on top of what's available in Debian repositories, and which packages does it merely need to enable / run?


• How much of the changes to code / new code Devuan has introduced would theoretically be usable/useful on Debian even with systemd, as opposed to code changes which are irrelevant with systemd in place?

If these answers differ significantly between Devuan Jessie and ASCII, please answer regarding ASCII.

Devuan syncs all Debian packages with the exception of systemd (and for a bizarre reason file-rc in ASCII). It fixes anything that breaks due to these two packages missing and adds a bit of branding and changes a couple of defaults here and there.

The coding projects that devuan started are all dead as far as I can tell: LoginKit was supposed to be a replacement for logind (they use elogind now) but never got of the ground. Vdev was supposed to replace udev, but has not seen changes in ages and devuan now uses eudev instead. There are some small network management things, but nothing production ready. The most work in devuan went into the infrastructure, but most of that makes little sense for Debian. Other distributions downstream of Debian might find some pieces useful though.

Don't hold your breath wrt. "dependency mess": For ASCII Devuan has given up on removing libsystemd0 dependencies from Debian packages (they started removing that for Jessie and are rolling back on that now). They also recently added a logind-clone, and can now ship Debian packages that depend on systemd-logind unchanged.

There seems also little willingness to work with Debian developers on packages.

For an overview of packaging activity in Devuan there are the build server logs at https://ci.devuan.org/view/All/builds with all the packaging activity. You find all the devuan-specific packaging work in those logs. The amount of activity is not overwhelming, so it is a nice way to stay up-to-date.

Very roughly, without looking up details:

The main changes Devuan has to made are in the package dependencies, because systemd has turned into a big fat unmodular clump that extends its tendrils (dependencies) into a lot of other packages (e.g. desktop) where you'd scratch your head and ask yourself why this is necessary. This made it really difficult to run Debian without systemd (I tried to do that long enough). You'd upgrade an innocent package, and bam, via a hundred indirections you got systemd again.

1) Just the traditional sysv init system, that has always been in Debian. Devuan is not so much about needing new packages, it's about using Debian like it was used before the systemd mess.

2) See above - in terms of available packages, there's not much change. There are a few "ghost" packages that are more or less empty, but are used in Debian for systemd, to satisfy dependencies.

3) I don't think there are changes to actual code. Sorting out the dependency mess would have been really useful for Debian (then there would be no need for Devuan), but apparently the Debian maintainers were not willing to do that.