Issue Description
NixOS Version: 25.11
Virtualization Tool: Virt-Manager / Libvirt
Livbirt version before update: 11.4.0
Libvirt version after update: 11.5.0
Network Configuration: Default NAT network not functioning as expected.
Current Setup
-
Network Configuration in Virt-Manager:
- The default network is defined as follows:
<network> <name>default</name> <uuid>fc7e73df-8b5d-4624-84c6-18da927b7cd7</uuid> <forward mode="nat"> <nat> <port start="1024" end="65535"/> </nat> </forward> <bridge name="virbr0" stp="on" delay="0"/> <mac address="52:54:00:d4:a9:02"/> <ip address="192.168.122.1" netmask="255.255.255.0"> <dhcp> <range start="192.168.122.2" end="192.168.122.254"/> </dhcp> </ip> </network>
- The default network is defined as follows:
-
Terminal Output:
- When checking the active virtual machines with
virsh list, no VMs are listed:virsh list Id Name State -------------------- - The output of
ip addrshows the following relevant interfaces:3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc htb state DOWN group default qlen 1000 link/ether 52:54:00:d4:a9:02 brd ff:ff:ff:ff:ff:ff inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
- When checking the active virtual machines with
UEFI virtual machines also have issues, and do not start:
Error starting domain: operation failed: Unable to find 'efi' firmware that is compatible with the current configuration
Traceback (most recent call last):
File "/nix/store/3s7rckxjck002zfmqcvj5aqlav6h44kc-virt-manager-5.0.0/share/virt-manager/virtManager/asyncjob.py", line 71, in cb_wrapper
callback(asyncjob, *args, **kwargs)
~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/nix/store/3s7rckxjck002zfmqcvj5aqlav6h44kc-virt-manager-5.0.0/share/virt-manager/virtManager/asyncjob.py", line 107, in tmpcb
callback(*args, **kwargs)
~~~~~~~~^^^^^^^^^^^^^^^^^
File "/nix/store/3s7rckxjck002zfmqcvj5aqlav6h44kc-virt-manager-5.0.0/share/virt-manager/virtManager/object/libvirtobject.py", line 57, in newfn
ret = fn(self, *args, **kwargs)
File "/nix/store/3s7rckxjck002zfmqcvj5aqlav6h44kc-virt-manager-5.0.0/share/virt-manager/virtManager/object/domain.py", line 1384, in startup
self._backend.create()
~~~~~~~~~~~~~~~~~~~~^^
File "/nix/store/rgkr4v1ndzlvpaa397xc9shj7x6zndkq-python3.13-libvirt-11.5.0/lib/python3.13/site-packages/libvirt.py", line 1390, in create
raise libvirtError('virDomainCreate() failed')
libvirt.libvirtError: operation failed: Unable to find 'efi' firmware that is compatible with the current configuration
Configuration
Here is the relevant part of my configuration.nix:
networking = {
hostName = "nixos";
networkmanager.enable = true;
modemmanager.enable = true;
wireguard.enable = true;
nameservers = [
"8.8.8.8"
"1.1.1.1"
];
};
programs = {
virt-manager = {
enable = true;
package = pkgs.virt-manager.overrideAttrs (oldAttrs: {
nativeBuildInputs = oldAttrs.nativeBuildInputs or [ ] ++ [ pkgs.wrapGAppsHook ];
buildInputs = pkgs.lib.lists.subtractLists [ pkgs.wrapGAppsHook ] oldAttrs.buildInputs ++ [
pkgs.gst_all_1.gst-plugins-base
pkgs.gst_all_1.gst-plugins-good
];
});
};
};
virtualisation = {
spiceUSBRedirection.enable = true;
libvirtd = {
enable = true;
qemu = {
vhostUserPackages = [ pkgs.virtiofsd ];
ovmf = {
enable = true;
packages = [
(pkgs.OVMF.override {
secureBoot = true;
tpmSupport = true;
}).fd
];
};
swtpm.enable = true;
runAsRoot = true;
};
};
};
Problem Statement
After updating my NixOS configuration using doas nixos-rebuild switch --flake ., the default virtual network (virbr0) is showing as “DOWN” and is not functioning. Despite the network being defined and appearing active in Virt-Manager, I cannot see any active virtual machines with virsh list, and the network does not seem to be providing DHCP services as expected.
Steps Taken
- Verified the network configuration in Virt-Manager.
- Checked the status of the
virbr0interface usingip addr. - Restarted the libvirt service with
doas systemctl restart libvirtd. - Attempted to manually bring up the
virbr0interface usingdoas ip link set virbr0 up, but it remains in a “NO-CARRIER” state.
if it is actually related to the libvirtd veresion, I have yet to learn how to keep it at the old version.
I tried a regression to libvirt 11.4 but that didn’t solve the issue, both the virtual networks and VMs with UEFI are still non-functioning.
virtualisation = {
spiceUSBRedirection.enable = true;
libvirtd = {
enable = true;
package = pkgs.libvirt.overrideAttrs (old: {
version = "11.4.0";
src = pkgs.fetchFromGitHub {
owner = "libvirt";
repo = "libvirt";
tag = "11.4.0";
hash = "sha256-0bOX95Ly8d1/XZan/EyxI6JaACJvOu9QsTkFNQTreqI=";
};
});
qemu = {
vhostUserPackages = [ pkgs.virtiofsd ];
ovmf.enable = true;
swtpm.enable = true;
runAsRoot = true;
};
};
};