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Questions tagged [qemu]

QEMU stands for "Quick EMUlator" and is a processor emulator that relies on dynamic binary translation to achieve a reasonable speed while being easy to port to new host CPU architectures.

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QEMU hostfwd not working with multiple netdevs

With the following command I am able to ssh into the virtual machine on localhost:10022. /usr/bin/qemu-system-riscv64 \ -M virt -accel tcg -m 8192 -smp 8 \ -nographic \ -bios ...
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What capabilities do you lose when turning off COW on a qcow2 file?

I run a small internal cloud utilizing 3 redundant, live migration capable Ubuntu/Qemu/KVM hosts with ~30 mixed OS VMs. The Pool volumes are BTRFS and before any of you give me crap about it: this is ...
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KVM: Best performance for all guests

With KVM, what is the best way to provide the highest possible performance to all VMs? The host has a hexa-core processor and 64GB of ram. 3-4 VMs should run on it. The VMs are idle a lot of the time, ...
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Merging avhdx checkpoints into vhdx under Qemu/KVM

I recently switched over from Hyper-V to Qemu (KVM), and in migrating my VM’s unpleasantly discovered that I had neglected to use the Hyper-V tools to merge one of my Ubuntu VM’s disks containing ...
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Copy and paste from a QEMU VM with VNC graphics?

I run a headless server that uses qemu + kvm to run a few VMs, and I manage them with virsh + xml file definitions. Because this a remote / headless system, I set the graphics as VNC, and then with ...
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Modifying parent snapshot in QCOW2 internal snapshots tree

Faced one problem and cannot find any info on the net Let's say I have several snapshots on my VM running on .qcow2 image. For example, it has next tree: # virsh snapshot-list my_vm --tree clean | ...
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How to check if KVM nested virtualization is supported on ARM64 processor?

I have a virtual machine running RHEL 8.5 on an ARM64 (aarch64) processor - Arm Neoverse N1. Every tutorial I've found states looking at either /sys/module/kvm_amd or the /sys/module/kvm_intel folder ...
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KVM with VirtioFS on host, Windows Server guest, VirtioFS access denied

I have some successful setups of Linux guests under KVM with VirtioFS, even able to boot from theese folders without any "classical" drive images or dedicated partitions. Now, I have a need ...
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qemu - win11: this PC can't run Windows 11

When trying to execute the setup the setup stops after selecting the os type with the following result: "this PC doesn't meet the minimum system requirements to install this version of windows. ...
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qemu-kvm snapshot creations are extremely slow after a few first fast ones

Could anyone help me on this please? behavior I'm running several VMs with qemu-kvm and when creating some first few snapshots of a running VM, they are created super fast (roughly 10 seconds). ...
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Iptables Qemu KVM

i've VM on Qemu on my server, i habitually use UFW but with Qemu is not possible to use UFW (When i drop any from virtual interface, not working), but i can use IPTABLES (Or Other). How can i block ...
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How to pass-through multiple USB devices with the same Vendor- and Device-ID in QEMu/Libvirt?

I have three identical USB devices on my VM host that I would like to pass-through to a VM: I can pass-through only one device as they all have the same vendor- and device-ID, the element in the VM ...
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How to disable output to console after launching QEMU VM?

I have to run three VMs on QEMU. for VM in ctrl-vm src-vm dst-vm do case ${VM} in "ctrl-vm") mac_addr=00:00:00:00:00:01 tap=tap0 port=30020 ...
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KVM stuck in boot loop

I have a server here, running Ubuntu 16.04 and libvirt 4.0.0. It is hosting a single KVM, a Jenkins Server. This server however is stuck in a boot loop after it was shut down for maintenance. I cannot ...
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Linux bridge leaking traffic of shutdown vms

I've a linux bridge (br0) setup with netplan as the following: version: 2 renderer: networkd ethernets: eno1: dhcp4: no dhcp6: no bridges: probr: interfaces: -...
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QEMU - (Index=0) exists

I'm getting this index=0 exists error when I try to run qemu with this specific lines: Command: qemu-system-x86_64 ` -cpu "Penryn-v1" ` -boot order=c,once=d ` -m 4096 ` -smp 2,sockets=2,...
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QEMU-KVM, drbd and corosync - VM's doesn't work after reboot

On Debian 9.6 I've got QEMU-KVM Virtualisation. After electricity problems this machine just shut down. After switching it on again I can't start any VM because of this error: error: internal error: ...
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Installing pfsense 2.5.2 ( freebsd 12 ) in KVM

Seems that I am having an issue installing pfsense firewall which is build on freeBSD12 into a qemu/kvm in Ubuntu. When it starts to boot, prior to the 'Install Box' I get a kernal panic Image of fail ...
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2 answers
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QEMU KVM hangs "Booting from Hard Disk... "

Ubuntu 20.04 server (no GUI) as host several guests working perfectly, each with its own LV I created an LV for a VM called "test", similar to working guests Partitioned the LV: one ext4 ...
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Windows VM suddenly run very slow in KVM/QEMU

I have several times experience a Windows VM suddenly start to run extremely slow, seems mostly related to slow storage IO. Seen this in different versions, but in this particular case is Win10 LTSC ...
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How to configure hugepages on CentOS Stream 9

I need to reserve 12288 hugepages for QEMU/KVM virtual machines. I followed the guide in 3 easy steps to configure hugepages in RHEL/CentOS 7/8 but it looks like in CentOS Stream 9 the configuration ...
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What is an alternative of "virtio26" os-variant for Flatcar Linux installation on kvm-qemu using virt-install

Greeting to all! Details: The official tutorial for Flatcar kvm-qemu installation suggests to use "virtio26" os-variant. But in Ubuntu LTS 20.04 "osinfo-query os" doesn't show such ...
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kvm and libvirt: hotplug virtual disk as USB storage

Observations (1) A new virtual disk can be hot plugged into a KVM/qemu VM as a qemu virtio device, e.g. see question KVM and Libvirt - How do I hotplug a new virtio disk?. However, this requires PCI ...
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How to set SELinux boolean using custom policy?

I know that SElinux booleans can be set via setsebool like this: setsebool -P virt_qemu_ga_read_nonsecurity_files 1 But I want to set this boolean virt_qemu_ga_read_nonsecurity_files using custom ...
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2 votes
3 answers
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virsh autostart not working

root@virtual3:~# virsh autostart nstest Domain nstest marked as autostarted root@virtual3:~# virsh dominfo nstest Id: - Name: nstest UUID: 8cf691cd-7246-442b-a26b-...
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2 votes
1 answer
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QEMU/KVM guest VM cannot resolve DNS hostnames or SSH/ping from host

I have a QEMU/KVM-based virtual machine with CentosOS 6.4 that cannot fully connect to the Internet. I can ping IP addresses (ex. ping 8.8.8.8 works successfully), but domain names are not resolved (...
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Permissions of /dev/null wrong in KVM guest

My host node is RHEL7 running KVM from the 'updates' repo. On the host node, the permissions for /dev/null are: crw-rw-rw-. 1 root root 1, 3 Dec 18 04:45 /dev/null In an Alpine KVM guest (5.14, but ...
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QEMU - after dist-upgrade of Debian host, win10 guest state lost

I'm running a headless Debian host with a win10 guest that I seldomly login to via vnc. Last week I upgraded Debian from Buster to Bullseye, and that also upgraded QEMU from v3.1 to v5.2 (and libvirt ...
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Why I can't change qcow2 password via chroot

I have a Linux qcow2 image, and I want to change the root password. I combined qemu-nbd and chroot commands to access the filesystem in this qcow2 file. qemu-nbd --connect=/dev/nbd0 ./linux.qcow2 sudo ...
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How to enable external access to the Virtual machine on private link?

I would like to benchmark virtual networking of KVM-QEMU. For this purpose, I connect two servers (server 1, and server 2) with one wire. I use server 1 to run the QEMU VM and I want to access this VM ...
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Proper debian configuration for bridge/tap interface for use with QEMU

I am having troubles restoring my internet connection after bridging my network and a tap interface. I am using debian 5.10 and following this guide: https://wiki.debian.org/QEMU#Networking My ...
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KVM disk size stuck at 993M despite using --disk size=10. How do I set it to 10GB?

I create a vm using sudo virt-install \ --name ueransim \ --ram=2048 \ --vcpus=2 \ --disk size=10 \ --location /home/username/ubuntu-20.04.3-desktop-amd64.iso \ --graphics vnc,listen=0.0.0.0 \ --...
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passing nic to guest in qemu using iommu & vfio

I bought a 4-port network adapter PCIe card (Intel E1G44HT 10/100/1000Mbps PCI-Express 2.0 Server Adapter I340-T4) I am trying to install it in my hpZ600 workstation and pass it through to my guest VM ...
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How to connect QEMU directly to the outside network using command line?

My host has 1 Ethernet controller with the IP address 192.168.1.2/24, and I want the virtual machine to be on the same subnet with the address 192.168.1.3/24. Basically it is making a bridge interface ...
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Is it possible to pipe qemu-img into SSH target?

I tried the following command, but only an empty file is created on the target and the command stays open qemu-img convert -f raw -O vmdk /dev/sda1 - | ssh foo@bar "cat > /home/foo/foobar.vmdk&...
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QEMU freezes at "Booting from Hard Disk..." with -nographic

A QEMU VM, both the host and guest OS being Ubuntu 20.04. QEMU 6.1.0 is compiled without any special parameters. The guest was installed from a downloaded iso image of Ubuntu server. If I start the VM ...
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Why do you need serial port connection between QEMU quest and host?

I am new to qemu. I was exploring some commans to setup qemu VM. Can someone please explain why serail ports are required/desired between guest and the host? Also, what does '-serial pty' and -'serial ...
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How to get qemu watchdog working in Freebsd 12.1 guest

I am running a couple of OpnSense (based on FreeBSD 12.1) routers in qemu virtual machines in Proxmox 6.4. Promox has its own non-libvert way of configuring VMs, but to add a watchdog device, one adds ...
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Is a ZVOL considered copy-on-write anymore if I format it with another filesystem?

According to official requirements from Microsoft, SQL Server 2019 only supports either ext4 or xfs. I suspect that a Copy-On-Write filesystem such as btrfs or zfs may hurt the performance of the ...
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How to set vf-token on QEMU?

I'm trying to create VFs on a i350 NIC, which are to be attached to KVM machines. So far I can have vfio-pci enabled on my pf and create VFs under that PF which are on vfio-pci again (since I've ...
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libvirt bridge incoming traffic not forwarded

I have a public ip block 51.x.x.16/28 that I'm trying to use with libvirt/qemu VMs. Inside the VM (ip 51.x.x.18) I'm trying to create an outbound tcp connection (http). Using tcpdump on the host I can ...
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Qemu cloud-init nocloud-net static ip

I'm using ubuntu-cloud images and I'm trying to run cloud-init with nocloud-net -smbios type=1,serial=ds=nocloud-net;s=http://10.10.0.1:8000/ as described at https://cloudinit.readthedocs.io/en/latest/...
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Booting a Debian Live ISO on QEMU

Situation: A server: access only via SSH (no physical access, no KVM) a netboot OS (Debian/Jessie) 3 x 2T HDD 16G RAM Final goal: Building a ZFS pool with the local HDD and install Debian on a ZFS ...
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1 answer
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How run a dnsmasq inside QEMU, providing netboot service to other VMs

EDIT: WIP: The core reason for the failures explained below is due to me not bringing up the host TAP interfaces at the right time, if I allow QEMU to handle the creation of the tap devices, ...
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How can I recover the space in a qcow2 file after deleting snapshots, while retaining remaining snapshots?

I have a virtual machine that started out with 5 snapshots 1,2,3,4,5. I used qemu-img to delete snapshots 1,2,3. Snapshots 4 and 5 are still needed and were not deleted. How can I release the space ...
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Virsh console for Windows 10 VM (QEMU-KVM)

I'm trying to access a Windows 10 virtual machine from my Linux host by using virsh console. But when I do so, I get the empty console that many others have experienced. virsh console win10 Connected ...
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Loading a KVM guest with static IP using XML file

I have an XML template for the image I am loading on KVM using ansible. For now, the image loads without IP. I would like to know if there is a way to add static IP on the XML template so that my VM ...
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How to ensure that the changes in domain XML spec in libvirt takes effect?

I followed this host port forward with qemu through libvirt in user-mode networking answer to accomplish a certain task but it was only after a reboot that the ports were actually accessible. I tried ...
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How to move live QEMU-KVM VM without libvirt?

Let me start by saying that I read How to (properly) back up a live QEMU/KVM VM? But it does not seem to meet my need. I am looking for a solution to backup AND move a few QEMU-KVM VMs without ...
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Cockpit -- how to add user options to start VM with QEMU/KVM

I used Cockipt (host is the CentOS8) to create a guest VM (CentOS8 also). Now I have a task to configure the VM to use stuff from SPDK's VHOST. According SPDK docs I'm need to add follow lines to QEMU'...
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