54
votes
libvirt: "Failed to initialize a valid firewall backend"
Installing ebtables and dnsmasq seems to fix the problem. Don't forget to restart the libvirtd service.
The commands:
sudo pacman -Syu ebtables dnsmasq
sudo systemctl restart libvirtd
NOTE: do not ...
25
votes
Accepted
What is the difference and relationship between kvm, virt-manager, qemu and libvirt?
KVM is able to create VMs independently without any support of ther Hypervisors such as QEMU.
Yes and no; it can create VMs but cannot provide hardware other than CPU & RAM.
Why virt-manager ...
19
votes
No Auto Resize with SPICE and virt-manager
The gnome desktop, mutter, has some hotplug code that deals with the resize.
If you have any other desktop like xfce4 or KDE or a bare .xinitrc file running compiz like I do, you are pretty stuck, but ...
11
votes
Accepted
How to configure macvtap to let it pass multicast packet correctly?
libvirt's macvlan has gained support for multicast. Unfortunately it is disabled by the default setting trustGuestRxFilters="no", and the documentation is not explicit that this breaks multicast. As ...
11
votes
libvirt: "Failed to initialize a valid firewall backend"
This is the error that comes up if libvirtd was started without ebtables and/or dnsmasq installed. If you've got them installed and you're still having this issue, you probably need to restart the ...
10
votes
Accepted
Unable to connect to internet in Windows 10 VM using KVM/QEMU
Same problem here, appears to be a driver problem. This fixed it for me:
If you haven't done yet, download Windows VirtIO Driver ISO ('Stable virtio-win ISO' worked for me) and attach to guest CD ...
8
votes
How to configure macvtap to let it pass multicast packet correctly?
The answer by sourcejedi contains the solution, but maybe not explicitly enough. Using "virsh edit", set the trustGuestRxFilters attribute on the network device:
<interface type='direct' ...
8
votes
Accepted
kvm Error starting domain: unsupported configuration: Unable to find security driver for model selinux
To get the virtual machines backup and running
I ran the following, to edit the domain xml config file.
$ virsh edit some-virtual-machine / domain
Remove the following line, which was near the ...
8
votes
No Auto Resize with SPICE and virt-manager
I'm using Debian 10 and icewm as guest VM. When spice-vdagent is running I can manually adjust the screen size with xrandr --output Virtual-1 --auto
A change in the display size can also be observed ...
6
votes
Accepted
libvirt / KVM/QEMU - Networks: What does "Open Network" do?
This feature was described when it was added, in the post
[libvirt] [PATCH 1/3] network: new network forward mode 'open':
The new forward mode 'open' is just like mode='route', except that no
...
5
votes
Accepted
How to(Libvirt) attach floppy image device to guest VM?
You need device=floppy, dev=fda and bus=fdc, e.g.
<disk type='file' device='floppy'>
<source file='/var/lib/libvirt/images/floppy.vfd'/>
<target dev='fda' bus='fdc'/>
</disk&...
3
votes
Accepted
memory allocation never change for my virtual machine
You don't mention which hypervisor you're using, so I'm going to guess KVM, but my answer applies to Xen too. When you set currentMemory=16384 and maxMemory=32768, you are telling KVM to boot with 32 ...
3
votes
Accepted
Missing AESNI, RDRAND and RDSEED capabilities?
You must specify the CPU "model" that libvirt/qemu uses for the VM.
The simplest way is to use the "host" model, that will expose all libvirt/qemu supported flags from the host to the VM.
In libvirt ...
3
votes
Accepted
qemu virtual machine send desktop switching command to host
Here are the steps that worked for me:
Open "Virtual Machine manager" → Edit → Preferences. Go to "Console" tab and click the "Change" button next to the "Grab keys". Choose any key you ...
3
votes
virsh - list all mac addresses for all network interfaces of any type
You can use virsh to do this
# virsh domiflist vmname
For all the VMs use;
# for i in `virsh list --all --name`; do echo $i; virsh domiflist $i; done
3
votes
Accepted
How to coerce libvirt into making systemd include p0 when enumerating network interfaces?
When on bus 0, the generated network interface name depends on whether it sits on a PCI or a PCIe bus. PCI NICs are enumerated primarily in the short ens3 format while PCIe NICs get the longer enp0s3 ...
2
votes
Unable to resume KVM guest after rebooting host
I had the same issue, the problem was i was out of space. So I had to cleanup and free space in my home directory. And everything works perfectly as before.
Hope this help!
2
votes
Show qemu command line from virsh
It is also possible using virsh with the domxml-to-native subcommand:
virsh domxml-to-native qemu-argv --domain mydomain
2
votes
Show qemu command line from virsh
Just saw this question. In the hope it helps others, the easiest way to see the qemu command that was used, while the VM is running, is:
ps -ef | grep qemu-system-x86
2
votes
Accepted
Where are network config files supposed to be saved for libvirt?
On my (CentOS) based systems they are in /var/lib/libvirt/network (and this is the same for the libvirt.org wiki answer) but the Ubuntu Wiki suggests /etc/libvirt/qemu (in the libvirt guest ...
2
votes
Accepted
Creating a libvirt URI to hop to another host
Yes, it is possible. I have such setup,
Libvirt IRL: qemu+ssh://user@host/system
And the setup password-less access to your host over your gateway, such as in ~/.ssh/config (might need more ...
2
votes
Accepted
How do I count booting time?
If the virtual machines are Linux-based and using systemd as init service, you can use systemd-analyze:
[computer user]# systemd-analyze
Startup finished in 17.258s (kernel) + 5.936s (userspace) = ...
2
votes
Accepted
Qemu: Is it possible to have BOTH the virtual display and VGA passthrough in a Windows guest?
Looking-glass doesn't precisely answer the question, but it solves the underlying problem nearly perfectly -- providing GPU-accelerated VM graphics on the host desktop with the host's HID devices. ...
2
votes
How to install VM from ISO?
The error messages seem to tell the story.
"mount: only root can use "--options" option" - add a sudo in front of your command (or use sudo su first to switch to root). There's multiple things that ...
2
votes
USB redirection in libvirt
Based on some research you have encountered a bug. Here is the best voted solution I found but I can't test as I don't have your setup.
cat <<EOF >/etc/udev/rules.d/50-spice.rules
SUBSYSTEM==...
2
votes
Accepted
Making my KVM VMs accessible from the network
or is it better to somehow make the guests use my actual router as their gateway, instead of the one built in to KVM?
There is no gateway built in to KVM (nor a "default bridge" either). Your VM host ...
2
votes
Unable to connect to internet in Windows 10 VM using KVM/QEMU
Aparently libvirt does not handle nftables well [1].
You need to use the legacy backend [2]. These are the necessary packages
iptables ebtables dnsmasq firewalld
I had to also enable firewalld to get ...
2
votes
kvm/virt-manager boot selection
Even if you pass -boot menu=on to QEMU (which is what libvirt does for you), this option is not implemented by QEMU but rather by the firmware (typically SeaBIOS or OVMF). You have OVMF. In OVMF, ...
2
votes
Does IP required for bridge interface in KVM host
No, but also yes:
A bridge interface will still function as a bridge even if it does not have an IP address. (Bridges do not use IP addresses; they forward packets at MAC layer.)
But the interface ...
1
vote
Windows 10 VM Bootloop
I was able to boot by switching the cpu from host-model to qemu-64.
Performance seems fine, so I'll leave it like this unless I find a way to boot with host-model.
Only top scored, non community-wiki answers of a minimum length are eligible
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