How to adjust the timeout of a systemd device?

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1

I have a systemd device, dev-vboxguest.device, which is created through an udev rule in nixpkgs/virtualbox-guest.nix at 4263ba5e133cc3fc699c1152ab5ee46ef668e675 · NixOS/nixpkgs · GitHub.

Now I want to adjust the (start) timeout of this device in my system configuration, but there are no systemd.devices.* options, only for services etc. How can I adjust this timeout?

Background: I have a setup where I can either boot into my nixos, or where I can boot the nixos from another OS through Virtualbox’s raw physical disk access. When I boot natively however, the dev-vboxguest.device won’t appear (which makes sense), but causes a 90s delay in my boot process.

2

Found it, the solution for my case was:

systemd.units."dev-vboxguest.device".text = ''
[Unit]
ConditionVirtualization=oracle
'';

Which doesn’t set a timeout, but explicitly only activates (or tries to activate) the device when booting in VirtualBox.

Edit: It seems this is already done by the nixos-module: nixpkgs/virtualbox-guest.nix at master · NixOS/nixpkgs · GitHub

What I needed was to disable the network interface that VirtualBox provides when booting natively, i.e.:

  systemd.units."sys-subsystem-net-devices-enp0s3.device".text = ''
   [Unit]
   ConditionVirtualization=oracle
  '';

And enable the device that appears when booting natively with a similar unit that specifies ConditionVirtualization=none instead.

Edit 2:
Everything works fine during boot, but without specifying ConditionVirtualization=oracle for dev-vboxguest.device, it seems that nixos-rebuild switch tries to start dev-vboxguest.device (or probably rather virtualbox.service) and times out waiting for, taking 1:30m again.