- Users - libvirt List Archives

NVRAM storage live migration
by jchrist＠anexia-it.com 28 Apr '26

28 Apr '26

Hi, via virsh blockcopy I can live migrate disks between paths. Internally, this seems to use QEMU's drive-mirror or blockdev-mirror. Is something similar possible with the EFI NVRAM / vars file? blockcopy does not work, as judging by the code it only searches disk elements in the domain XML definition, which doesn't include single files like this. Under the hood, however, the vars file is represented in QEMU as a -blockdev. Judging by the docs for virDomainQemuMonitorCommand, it is unsafe to manually command QEMU to move this file around via drive-mirror and friends. Is there an alternative approach? Thanks, Jakob

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virt-host-validate should warn about false positives
by therandshow＠gmail.com 23 Apr '26

23 Apr '26

virt-host-validate seems to sometimes complain about freezer support on machines with cgroups v2 where it doesn't matter, it also reports lack of devices cgroup if the user isn't running as root. Ideally, it should report N/A on freezer support for cgroups v2 or just PASS because it has validated that it wasn't necessary. Or maybe just have a warning at the bottom, failure for the freezer cgroup only applies to cgroups v1 For devices cgroup, a warning if the user is running not as root and the test fails, you may need elevated privileges to check cgroup 'devices' or something along those lines. Or failing to put it in the output, it would be nice if these facts were more prominent in a troubleshooting page

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Migrating VM to new supervisor - general question
by fc26wuqa＠studserv.uni-leipzig.de 20 Apr '26

20 Apr '26

Hello, I planned to move my VMs to a new (VM) supervisor, because I want to use another operation system for it. I am doubting myself, if this is such a good idea. When all my VMs are on different disks, can I just install a different OS on the root partition and just import the qcow2 files afterwards. Or am I risking losing my VMs/disks? I am a little bit afraid of messing it up... Thank you.

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Windows 11 sound driver problem
by Owen Le Blanc 20 Apr '26

20 Apr '26

I have a Windows 11 system running under libvirt/qemu. A recent Microsoft software update overwrote the audio driver. Device manager would not let me install the one from the virtio ISO because it had determined that the "best driver was already installed". But sound wasn't working. I solved this by going into device manager and deleting the windows driver, then adding the viogpudo driver from the ISO manually. After rebooting the virtual machine, audio was working again. Yours, -- Owen Dr O V Le Blanc

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attaching a specific usb device to vm
by daggs 20 Apr '26

20 Apr '26

Greetings, I have two identical hdd to usb enclosures connected to a server which run two vms, lets call the foo and goo. I'm looking for the ability to connect a specific hdd to a specific vm, naturally using vendor and device is not possible and using bus+port will provide what I need however it does not persists incase of port change. I saw that using the hooks, libvirt provides the xml to the hook and read it from the output of the hook. I tried adding detection and adding accurate hostdev xml tag to the vm xml and I see it from the output of the hook execution in the prepare stage however, the system boots but the hdd is not visible in guest. the docs reference this feature only for migrate and restore ops, does this means I cannot use it in the prepare stage? if so, is there another way to do what I want? Thanks, Dagg

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LXC: net.unix.max_dgram_qlen
by Alexander Filatov 13 Apr '26

13 Apr '26

I want to set the sysctl net.unix.max_dgram_qlen parameter in LXC because the default value (10) is too small for me. Is it possible in some way without changing the source code of Linux kernel? I'm looking for the setting in XML configuration for an LXC domain and I can't find one. Setting it inside an LXC container (sysctl -w) is prohibited.

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Questions about migrating VMs (with virt-manager)
by fc26wuqa＠studserv.uni-leipzig.de 09 Apr '26

09 Apr '26

Hello, I want to migrate multiple VMs to a new host. In the process, several questions came up, where I could not find an answer. I am using virt-manager version 1:5.0.0-5+deb13u1. I reordered and renamed my storage pools: When migrating a VM, how can I move the VM to a specific storage pool? Will the VM be moved to a storage pool with the same name by default? When migration finishes, the VM on the source host will still be accessible but will shut down. Is that true? Can I prevent the VM from shutting down during the migration? Thank you.

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FYI: possible mailman service disruption 2026/04/08
by Daniel P. Berrangé 08 Apr '26

08 Apr '26

The hosting of the libvirt mailman instance will be moving to a new location tomorrow on 2026/04/08, at around 0900-1000 UTC. While we don't expect any significant loss of service, there could be minor short term, temporary disruption for sending emails while DNS records update. With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|

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enable nested virtualization inside VM
by fc26wuqa＠studserv.uni-leipzig.de 31 Mar '26

31 Mar '26

Hello, I want to set up a NAT network inside a VM (so far as I understand, the name for that is nested virtualization). Unfortunately I only have Shell Access to the VM, and am not hosting it. I installed debian. The output of `uname -a`: Linux kvm1 6.12.74+deb13+1-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.74-2 (2026-03-08) x86_64 GNU/Linux When I run `kvm-ok` it says "INFO: Your CPU does not support KVM extensions KVM acceleration can NOT be used". When I try to load `kvm_intel` into the kernel (even with nested=1 option), it says "modprobe: ERROR: could not insert 'kvm_intel': Operation not supported". I can't start a network, there is no `/dev/kvm` device. I installed libvirt with `apt install --no-install-recommends qemu-system libvirt-clients libvirt-daemon-system`. Is there a way to enable libvirt support? For me, or the admins that host the VMs? Thank you.

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double startup of sessioned vm causes user systemd service to fail
by daggs 11 Mar '26

11 Mar '26

Greetings, I'm running 3 vms in session mode on arch linux, I need each vm to startup on boot. libvirt version is 12.1.0. from what I understand, libvirt-guests lacks session support so I went to look and found that I can use per user systemd service, using this doc: https://wiki.archlinux.org/title/Systemd/User I defined each user to linger, created a service file and enabled it for each user. I've rebooted the machine and found out that not all the vms started, some of them have failed, each boot the outcome differs but usually there is atleast one vm which doesn't startup. I've check the status of the service and found that in the cases where the boot failed, the error was that the vm is already active, however virsh list shows ihe vm is off. none of the vms is marked as autostart. how can I find out who is the other source that starts up the vms? I assume it is something internal of libvirt. ideally, if possible, i'd like to use something from within libvirt or at least stop whatever autoboots the vms. Thanks, Dagg

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