[Nix-dev] systemd in initrd

[Luca Bruno]

I did a very quick test. Added the following components to the initrd,
according to arch linux systemd hook [1]:
lib/systemd/systemd
lib/systemd/system-generators/systemd-fstab-generator
lib/systemd/system-generators/systemd-gpt-auto-generator
bin/systemd-tmpfiles
lib/libcap.so.*
lib/libpam.so.*

The compressed initrd has grown from 5.6mb to 6.2mb. Uncompressed it has
grown from 19mb to 20.5mb. This is comparable to e.g. enabling luks.

In the hope that only those binaries are sufficient (no journal for
now), plus some units, it seems to be feasible.

I believe there won't be any official agreement until a working
deliverable. That is, it's hard to know in advance whether it works well
in practice or not.

I'm probably going to start a branch on my repository for this work
soon, plus setting up an hydra for building tests against the branch.

If there's any technical blocker, or if this is unwanted because
somebody is working on a better initrd process for nixos, or anything
that makes this obsolete, please let me know.

Best regards,

[1]
https://projects.archlinux.org/svntogit/packages.git/tree/trunk/initcpio-install-systemd?h=packages/systemd