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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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guestmount: write in a VMDK are not saved after unmount

I have a VMDK and I mount it using the guestmount tool like so: # guestmount -a my-disk.vmdk -i --rw mount/ The VMDK filesystem is well mounted in the mount/ directory. I create a dummy file in the ...
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QEMU crashed while trying to boot up i.MX6q device kernel

When tried to boot up Kernel uImage of an i.MX6q based embedded device, it seems that QEMU crashes with "Unable to handle kernel NULL pointer dereference at virtual address 00000044". Before crashing ...
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Proxmox: how to access a ZFS volume directly through guest?

That may sound like a strange use case, but is there a way to access a ZFS volume directly through an LXC container or a Qemu VM with Proxmox? I'd like to have incremental backups pushed to my guest ...
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XP KVM stuck at “Booting from Hard Disk”

Just to see if it could be done (and if so, move other physical XP machines to VM environments), I took the hard drive out of a decommissioned laptop, captured a WIM of it, and applied it to a QCOW2 ...
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34 views

Q: Unable to create 'live' snapshot of running KVM using virsh

I was kindly directed to here, Serverfault from Stackoverflow to pose my question. I'm running the following command on a RHEL7 hypervisor to create a live backup (disc image) of a running kvm, ...
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37 views

KVM guest gets into paused state shortly after being started

I have two very similar x86_64 machines running the same kernel (4.7.8), and the same version of libvirt. The only difference between the two machines is the amount of memory they have, machine A has ...
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62 views

Missing KVM snapshots in virt-manager

I need to resize an image and receive an error when using qemu-img the resize is not supported because snapshots exist. Sure enough, even though virt-manager does not show any snapshots, I see the ...
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Ubuntu 18.04 qemu lvm vnc issue

I just stumbled across a very strange issue with qemu and vnc / lvm on an fully updated vanilla Ubuntu 18.04: I set up am VM through libvirt: virt-install -n web_devel -r 2048 --disk path=/var/lib/...
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53 views

Kernel panic when booting qemu virtual machine

I usually install template virtual machines on a dedicated server and then copy the disk to other production servers. It has worked for years and still works today in all cases but one. I have ...
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55 views

Certain network request errors only inside VMs

I have Proxmox 5.2 installed on NUC for over a month and everything work fine. In the recent days, I decided to create a new workstation VM machine, and noticed something strange. Certain network ...
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configured cpu count is not reflected in libvirt/KVM Windows10 guest

I have a libvirt domain configuration, where the cpu-related settings for a Windows 10 guest are configured as follows <domain> <!-- ... --> <vcpu placement='static'>3</vcpu&...
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78 views

Installing Ubuntu 18.04 VM with Raid1 on ISCSI Server

I'm trying to create a VM (Both Guest and Host are Ubuntu Server 18.04) that uses 2 ISCSI Targets as a RAID 1 for the operating system. The goal is to have 2 Different ISCSI Servers that each hold 1 ...
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48 views

oVirt qemu-kvm listening on wrong IP

I'm new to oVirt but managed to configure it and take over the console on an IPv4 network, using VNC instead of spice. However, I've noticed that the qemu-kvm process only binds to the IPv4 interface ...
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qemu-nbd mount windows parition

I'm currently trying to mount NTFS partition from a qcow2 image on Debian9. I tried with linguestfs and qemu-nbd, that's not working libguestfs but using qemu-nbd i can mount the qcow2 image on /dev/...
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195 views

kvm/libvirt backup: how to ensure a consistent fs during online blockcommit?

I want to create online backups of a KVM Windows 10 virtual machine that is managed by libvirt. I have the qemu agent setup in the guest. If found this wiki entry that suggests the following: 1. ...
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1answer
68 views

Using host DHCP server with QEMU user mode (slirp) networking

I am trying to debug my own DHCP server (for PXE), and I want QEMU to net boot from it. For that, it needs to send DHCPDISCOVER packet to 255.255.255.255 that should reach host network where DHCP ...
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152 views

Route QEMU VM traffic through hosts VPN

tl;dr Host connects via VPN to the internet and a VM on this host doesn't go through this VPN (but it should). I think the network config isn't quite correct. The host The host (arch Linux) connects ...
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133 views

Delayed start for Guests KVM/libvirt

Looking for any pointers anyone may have to introduce a delayed start for KVM guests i.e. 30 seconds between starting each virtual server rather than starting them all at once which thrashes the disks ...
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74 views

How to make virt-install do an unattended install with an image that installs unattended on real hardware?

I built an Ubuntu 16.04 installation image. It reliably installs unattended on real computers--no preseed file, no human input. When I try to install this image in a KVM/qemu virtual machine, I must ...
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349 views

KVM-QEMU Windows Guest Memory Speed

How to speed up memory in Windows guest running on KVM-QEMU hypervisor? The memory speed differs between Ubuntu guest and Windows 2016 Server on the same node quite a lot. Same benchmark tool counts ...
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330 views

Mount URL as cdrom/iso KVM/QEMU

I am looking for a way to mount an ISO as a cd rom, according to libvirt docs (referenced below) it should be possible, additionally in the question referenced below. I am aware of this question, ...
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309 views

QEMU host and guest on the same network

I am trying to get my QEMU guest on the same network as my host, I know that when you boot a QEMU image it assigns it a private IP, so I have been trying to create a bridged network. The host machine ...
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97 views

QEMU QMP How to find device to use drive_backup?

I would like to use backup_drive command to copy disks and their snapshot in one image. Unfortunately, each time i use the command : virsh qemu-monitor-command VM_NAME --hmp drive_backup device=...
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101 views

QEMU and point-to-point link between VMs without bridge

The most common practice to connect VMs together is to use tap interfaces with the bridge between them. On a linux, bridge driver filters some classes of link-local multicast traffic, such as LACP ...
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Cannot redirect QEMU output to terminal using -nographic flag

I'm very new to QEMU. So I tried installing Debian in QEMU image following this instruction https://wiki.debian.org/QEMU. I first created an image. qemu-img create -f qcow2 debian.qcow 2G Then ...
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328 views

How much memory does a qemu disk cache writeback mode use?

I use Proxmox with ZFS ZVOL or LVM-thin for the disk volumes and it is said that using disk cache writeback mode will increase memory usage more than allocated. Is there a way to check, limit, and ...
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46 views

Vm connect to everywhere but the host

I have the following issue. Vms in virsh net2 are fine. Vms in net1 connect everywhere but the host. They can ping and connect to each other including vms in net1. Vms in net2 can only connect to ...
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28 views

QEMU clarifications and setup optimizations

We are using qemu with kvm acceleration. I wanted to understand the -drive flag, currently we are using it as follows: -drive file=<qcow2 snapshot file> if=virtio I have the following ...
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48 views

How to compile qemu-guest-agent - centos 6?

Can anyone provide a way to compile the latest version of qemu-guest-agent on CentOS 6? The repo version is too old for my needs, but i can't find any way to compile only it, without the whole qemu-...
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171 views

Upgrade QEMU/KVM on Ubuntu 16.10

I am hoping this is the correct forum on which to introduce my question as I am new to Ubuntu/linux world... and KVM Hypervisor. I am looking at upgrading the current version of KVM virtualisation ...
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164 views

KVM: What is stored in var/lib/libvirt/qemu

My Question is "What is stored in the /var/lib/libvirt/qemu folder?" Is this used as somekind of backup folder ? Backgroundinformation: I have a Debian Server with a running KVM installation(+libvirt)...
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39 views

qemu error while restoring snapshot

I made a snapshot of a Windows 10 VM and now if I try to restore it with virt-manager or with this command virsh snapshot-revert win10 "bef kg" I get this error: error: internal error: qemu ...
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103 views

How to pre-install and pre-configure selinux in a kvm/qemu guest image using docker?

I'm working in a company where we need to distribute our image running SE-Linux inside. The product uses virtualization for additional security, thus we have got a setup with a linux host, running ...
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192 views

KVM/QEMU: cannot attach-device (disk) to a live domain

I'm trying to add a new disk to a running guest/domain (Win10) I succeed in using virsh attach-disk... --live and also using virsh attach-device.. --config But using: virsh attach-device SRV13 /tmp/...
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119 views

Handling VMCALL with libvirt (qemu-kvm)

I am using libvirt with qemu-kvm to manage virtual machines. The guest makes a vmcall which I want to be notified of, e.g. via a callback function. I know it's possible with 'pure' KVM, but does the ...
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Can't launch instances on new Devstack installation

I just "successfully" installed Devstack on my Ubuntu Server 16.04 LTS. I can connect to the Horizon Dashboard without problems but when i try to launch an instance i get errors. If it try run a ...
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96 views

Enabling KSM: Restart of libvirtd necessary?

I've just enabled ksm on one of our hypervisors with lots of running VMs (qemu-kvm) that all are using the same operating system. Anyway, pages_sharing and pages_shared both still show 0: root@...
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KVM: Host has 2 IP addresses on isolated network

I set up a machine with Ubuntu 16.04 and KVM running a couple of VMs. I created a virtual network (virbr1) which is supposed to connect some of the VMs so I added this network to those. One of them is ...
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95 views

Libvirt nwfilter with multiple IPs

I'm trying to apply a nwfilter rule for two networks on the same guest interface, like so: ~ # virsh nwfilter-dumpxml 1081532-private-both <filter name='1081532-private-both' chain='root'> &...
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407 views

Kernel Panic on Guest-VM (Debian 9)

I have two servers running with Debian Jessie Kernel 3.16.0-5-amd64. Both servers have the exact same configuration, only hardware differs. I use KVM as hypervisor together with QEMU on both servers. ...
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316 views

QEMU Network bridging for having a public IP

I simply want that my QEMU VMs have a public IP so I can run multiple servers in the same machine. I've read a lot of wikis, guides, tutorials, forum threads and anything related to this but still no ...
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149 views

What's the safest way for backup and restore external snapshot using virsh libvirtd

Dears, I've followed the following steps in order to get a snapshot of a running VM on my KVM, but actually i'm not sure if that the correct way or no : /usr/bin/virsh snapshot-create-as \ --domain ...
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955 views

KVM gets stuck at “Booting from ROM”

I created I a ubuntu 16.04 vm with a kickstart file using the following xml <domain type="kvm"> <name>""" + name + """</name> <memory unit='GB'>1</memory> <vcpu>1&...
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984 views

qemu-kvm reclamation of memory from low-use guests

Is there a way to transparently reclaim, or prevent usage of, memory from a qemu-kvm guest? Scenario A: A guest uses 8GB of RAM during peak hours, it returns back to 4GB of usage at night, but the ...
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868 views

Permission denied error when launching instance (“Could not open backing file”)

Working with OpenStack, installed from packages available on Debian testing (buster). When I try to launch an instance, it fails after building with this message in nova-compute.log: Could not open ...
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1answer
3k views

KVM gets stuck at “Booting from hard disk”

I am trying to run Ubuntu-server-16.04 virtual machine on a KVM converted from .vhdx (Hyper-V) to .qcow2 (KVM). When I import my virtual disk image and start virtual machine, the KVM hangs on "...
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1answer
21 views

Retrieving libvirt-commands to hypervisors

Libvirt is cool, but I need to port a VM from it's configuration to bare QEMU or Xen. To reproduce the setup, I need the commands send to the specific Hypervisors in order reproduce the VM in the ...
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70 views

KVM Ubuntu USB Passtrough

I currently try to add a Hauppauge DVR Tuner (USB) to a KVM Machine. Both (Host and Guest) are running Ubuntu. This is my XML Guest File: https://pastebin.com/gBvFhsXs I already tried to follow ...
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99 views

KVM Bridge comparable to VMWare virtual switch

I have 4 physical NICs, one I have made a bridge already; ifcfg-bridge1-en1 ifcfg-enp2 ifcfg-enp3 ifcfg-enp4 Each of those NICs are different VLANs and Subnets. VLAN 24, 101, 102 ...
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2answers
867 views

Qemu TRIM and discard on a physical SSD device

I am running Windows 7 in a Qemu/KVM with a passed through GPU which I use for work-related stuff. I recently got fed up by it's unprecedented slowness due to it running off a mechanical drive, so I ...