Since e791519f0f ("nixos/qemu-vm: use qemu_kvm"), VMs generated with
nixos-rebuild build-vm use the qemu_kvm package instead of the qemu
package. (The difference between them is that qemu_kvm is only built
with support for the host architecture, not all architectures.)
But with this change, nixos-rebuild build-vm would now depend on
_both_ QEMUs, because the guest agent module was still using the one
from the full QEMU package. There's no need for it to use this
instead of the lighter qemu_kvm, because the guest agent shouldn't be
affected by which platforms QEMU can emulate.
The default has been unchanged for a decade. Space is cheaper and
software catches up with that. Let's not make our testing harder
than necessary by default.
qemu_kvm is only built for one architecture, so it's smaller and takes
MUCH less time to build if it has to be built from source. And this
module doesn't support running a VM for one architecture from another
architecture, so the one architecture is all we'll need.
pathsInNixDB isn't a very accurate name when a Nix store image is
built (virtualisation.useNixStoreImage); rename it to additionalPaths,
which should be general enough to cover both cases.
Add the `useNixStoreImage` option, allowing a disk image with the
necessary contents from the Nix store to be built using
make-disk-image.nix. The image will be mounted at `/nix/store` and
acts as a drop-in replacement for the usual 9p mounting of the host's
Nix store.
This removes the performance penalty of 9p, drastically improving
execution speed of applications which do lots of reads from the Nix
store. The caveats are increased disk space usage and image build
time.
The headless option broke with 7d8b303e3f
because the path /bin/vmware-user-suid-wrapper does not exist in the
headless variant of the open-vm-tools package.
Since the vmblock fuse mount and vmware-user-suid-wrapper seem to only
be used for shared folders and drag and drop, they should not exist in
the vmware-guest module if it is configured as headless.
Move all `virtualisation.libvirtd.qemu*` options to a
`virtualisation.libvirtd.qemu` submodule.
Also for consistency, add `virtualisation.libvirtd.qemu.swtpm.package`
(only new option during this refactor.)
I realized quite recently that running a test VM - as documented in the
manual - like
QEMU_NET_OPTS='hostfwd=tcp::8080-:80' ./result/bin/nixos-run-vms
doesn't work anymore on `master`. After bisecting I realized that the
introduction of a forward-port option[1] is the problem since it adds a
trailing comma even if no forwarding options are specified via
`virtualisation.forwardPorts`. In that case, the networking options
would look like `-netdev user,id=user.0,,hostfwd=tcp::8080-:80' which
confused QEMU and thus the VM refused to start.
Now, the trailing comma is only added if additional port forwards are
specified declaratively.
[1] b8bfc81d5b
The current name is misleading: it doesn't contain cli arguments,
but several constants and utility functions related to qemu.
This commit also removes the use of `with import ...` for clarity.
