epub manuals are holding back the transition away from docbook, and
cursory research does not suggest that they are used very much. it's
still very early in the 23.11 release cycle, so if we're going to find
out just how many people do use the epub manuals it should be now.
this need not be the end of epub manuals. nixos-render-docs could be
extended to also export epubs, but that has not been done yet since it's
going to be some effort with unknown real-world usefulness.
As with many things, we have scenarios where we don't want to boot on a
disk / bootloader and also we don't want to boot directly.
Sometimes, we want to boot through an OptionROM of our NIC, e.g. netboot
scenarios or let the firmware decide something, e.g. UEFI PXE (or even
UEFI OptionROM!).
This is composed of:
- `directBoot.enable`: whether to direct boot or not
- `directBoot.initrd`: enable overriding the
`config.system.build.initialRamdisk` defaults, useful for
netbootRamdisk for example.
This makes it possible.
This is necessary because this test relies on switching the root fs to an empty one which
does not have a Nix store available in stage 1, therefore, we have to make this test
host-store only.
A better fix in the long term is to evaluate whether this is worth to enable a proper
Nix store image for it with EROFS?
This essentially backports
https://github.com/systemd/systemd/pull/27791. `systemd-networkd.service`
is sent the `SIGTERM` signal, but it is not required to be stopped
before `initrd-switch-root.target` is reached, despite the use of
`systemctl isolate initrd-switch-root.target`. This is because when
there is no ordering at all between two units, and a transaction stops
one and starts the other, the two operations can happen
simultaneously. This means the service could still be running when
`switch-root` actually occurs. Then, stage 2 systemd will see the
service still running and decide it doesn't need to add a start
operation for it to its initial transaction. Finally, the service
exits, but only after it's already too late. If, however, there is any
ordering at all between a stopping unit and a starting unit, then the
stop operation will be done first. This way, we ensure that the
service is properly exited before doing `switch-root`.
This is something to keep in mind going forward. There may be other
services that need this treatment. These `before` and `conflicts`
definitions are the correct way to ensure a unit is actually stopped
before you reach initrd-switch-root
