Previously, `vfs_snapper` was only built if `dbus` was found.
Now, `vfs_snapper` is enabled by default (on Linux)
and it requires dbus to be available:
```
Checking for dbus: not found
vfs_snapper is enabled but prerequisite dbus-1 package not found. Use
--with-shared-modules=!vfs_snapper to disable vfs_snapper support.
```
We could pass `--with-shared-modules=!vfs_snapper` to disable it,
but currently pass `--with-shared-modules=ALL`,
so add dbus as a dependency instead.
`nixos-rebuild build-vm-with-bootloader` currently fails with the
default NixOS EFI configuration:
$ cat >configuration.nix <<EOF
{
fileSystems."/".device = "/dev/sda1";
boot.loader.systemd-boot.enable = true;
boot.loader.efi.canTouchEfiVariables = true;
}
EOF
$ nixos-rebuild build-vm-with-bootloader -I nixos-config=$PWD/configuration.nix -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-20.09.tar.gz
[...]
insmod: ERROR: could not insert module /nix/store/1ibmgfr13r8b6xyn4f0wj115819f359c-linux-5.4.83/lib/modules/5.4.83/kernel/fs/efivarfs/efivarfs.ko.xz: No such device
mount: /sys/firmware/efi/efivars: mount point does not exist.
[ 1.908328] reboot: Power down
builder for '/nix/store/dx2ycclyknvibrskwmii42sgyalagjxa-nixos-boot-disk.drv' failed with exit code 32
[...]
Fix it by setting virtualisation.useEFIBoot = true in qemu-vm.nix, when
efi is needed.
And remove the now unneeded configuration in
./nixos/tests/systemd-boot.nix, since it's handled globally.
Before:
* release-20.03: successful build, unsuccessful run
* release-20.09 (and master): unsuccessful build
After:
* Successful build and run.
Fixes https://github.com/NixOS/nixpkgs/issues/107255
The shell script coming with the vendor-provided udev rule simply
starts dlm.service (and sets up some symlinks), and stops dlm.service if
that was the last card plugged in.
On NixOS, some of the cat/grep/sed commands are not available, causing
the script to fail.
Turns out, the symlinks aren't needed at all. Archlinux ships their own
script
(https://aur.archlinux.org/cgit/aur.git/plain/udev.sh?h=displaylink),
which only starts and stops dlm.service, depending on whether there's
cards left or not.
We can further optimize this by simply starting dlm.service on the first
card, and not stopping it at all. Considering dlm won't get stopped if
one of multiple cards is unplugged, it seems to handle disconnects.
