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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26
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2answers
14k views

Difference between KVM and QEMU

I have been reading about them for sometime. As of now I have a clear understanding of what they do. KVM supports hardware virtualization to provide near native performance to the Guest Operating ...
15
votes
4answers
29k views

KVM: Which CPU features make VMs run better?

We are using Ubuntu 12.04 with the following parameters: Dell R910 Kernel 3.2.0-25-generic #40-Ubuntu SMP x86_64 x86_64 x86_64 GNU/Linux kvm 1:84+dfsg-0ubuntu16+1.0+noroms+0ubuntu13 qemu-kvm ...
15
votes
2answers
2k views

understanding relationship between Qemu and KVM

What is the difference between KVM and Qemu? As I understand, latter is able to provide "user mode emulation" which means that one can run a single executable built for some other architecture like ...
11
votes
1answer
4k views

Read/write access for passthrough (9p) filesystems with libvirt/qemu?

I have recently started experimenting with the support for passthrough filesystems in recent versions of KVM/QEMU/libvirt. Making the filesystems available for read access has "just worked", but I'm ...
10
votes
2answers
8k views

free up not used space on a qcow2-image-file on kvm/qemu

we are using kvm/qemu with qcow2-images for our virtual machines. qcow2 has this nice feature where the image file only allocates the actually needed space by the virtual-machine. but how do i shrink ...
8
votes
2answers
2k views

How to quit QEMU monitor?

I launched KVM VM with this command: kvm /kvm/hdd/v1/v1-1.raw -m 512 -daemonize -smp 2 -nographic -net nic,model=virtio,macaddr=aa:aa:aa:aa:aa:01 -net tap,ifname=tap0 -monitor ...
8
votes
1answer
1k views

KVM/Qemu, Ubuntu: Why do more guests CPUs enhance Disk-I/O rapidly?

We have an Heartbeat/DRBD/Pacemaker/KVM/Qemu/libvirt cluster consisting of two nodes. Each node runs Ubuntu 12.04 64 Bit with the following packages/versions: Kernel 3.2.0-32-generic #51-Ubuntu SMP ...
8
votes
2answers
6k views

Monitor VM's resources (CPU, RAM etc)

I'm testing Openstack and i'd like to know how can i find out about resource utilization inside instances (Virtual Machines). Openstack uses kvm, qemu and libvirt in my testing environment. Is there ...
7
votes
3answers
2k views

QEMU-KVM Linux virtualization on the command line

I recently discovered that qemu-kvm has a very promising -curses option that, instead of starting an X window, will show a nice ncurses output from the guest suitable for managing a Linux guest from ...
6
votes
2answers
150 views

Accessing the partitions on an LVM volume

Suppose you have an LVM volume /dev/vg0/mylv. You have presented this as a virtual disk to a virtualised or emulated guest system. During installation the guest system sees it as /dev/sda and ...
6
votes
2answers
1k views

kvm and qemu host: Is there a limit for max CPUs (Ubuntu 10.04)?

Today we encountered a really strange behaviour on two identical kvm and qemu hosts (Dell R910). The host systems each have 4 x 10 Cores, which means that 40 physical cores are displayed as 80 within ...
6
votes
2answers
10k views

Changing boot device for a QEMU-KVM virtual machine

I am trying to change the boot device for a VM. I go to the VM's XML file in /etc/libvirt/qemu and set <boot dev='cdrom' />. Still, it attempts to boot from the harddrive instead of the cdrom. ...
6
votes
1answer
600 views

Maximizing throughput of virtual file systems

I've been using a QEMU system to build software. The problem I've been having is that the system seems to suffer from extremely slow disk access. This is not necessarily a problem as it's not really a ...
6
votes
1answer
984 views

TCP/IP performance tuning under KVM/Qemu

With more and more companies switching to public cloud services, I'm curious what you guys' thoughts are on TCP/IP tuning in the cloud. Is it worth bothering with? Given that you don't have access to ...
5
votes
2answers
3k views

Filesystem passthrough functionality in Centos 6.2?

I have a CentOS 6.3 machine currently running 2 virtualized CentOS 6.2 machines via KVM/QEMU/Libvirt. I'm trying to setup filesystem passthrough between the guests and the host. However the option is ...
4
votes
1answer
15k views

How to convert a raw disk image to a copy-on-write image based on another image for use with kvm and virt-manager?

I have a virtual Windows machine running on kvm. Presently it has a 90GB raw disk image. I would like to clone this VM without having to keep two copies of the 90GB raw disk image around. It seems ...
4
votes
2answers
811 views

Issue with creating an Windows 2008 Virtualized image with qEmu

I'm trying to create a qemu image of a 64bit Windows 2008 Server install. It will be used on Openstack as an instance. The Virtualization environment [of qemu] is being run from a VMware virtual ...
4
votes
2answers
122 views

Migrating physical machine to KVM

I have a fairly old debian machine that I need to migrate to KVM-Qemu. What I started is to make a tarball of the root filesystem: tar -cpf rootfs.tar --exclude='dev/*' --exclude='proc/*' ...
4
votes
0answers
755 views

QEMU: Solaris 11 / Sparc64 Guest on Linux / X86-64 Host [closed]

I'm trying to run a Solaris 11 / Sparc64 guest on a Linux/x86-64 host. I've cloned the qemu project and configured/compiled it with sparc64 support (./configure --target-list="sparc64-softmmu"). I've ...
3
votes
3answers
159 views

attaching usb dongle to KVM VM

I'm struggling to connect a usb device, that gets detected correctly by the host, to a kvm vm. I have a freshly installed Ubuntu Server 14.10 as KVM/QEMU host. I set up an Ubuntu vm using this ...
3
votes
1answer
69 views

What can be improved in my first qemu/kvm run?

Just started using kvm (qemu? I'm quite fuzzy with the terminology). To test if everything works fine, I created logical volume on my lvm, and then started virtual machine using: qemu-system-x86_64 ...
3
votes
3answers
5k views

libvirt and qemu/kvm -snapshot option

Using libvirt, I want to use QEMU's '-snapshot' option. That way, when the machine shuts down, all of the disk changes that were made get destroyed. Here is the manual for the -snapshot option: ...
3
votes
2answers
831 views

is it possible to install qemu inside linux ami on ec2?

well i tried to install it but gont an error . kernel-2.6.35.11-83.9.amzn1.i686 has missing requires of mkinitrd >= ('0', '6.0.91', None)
3
votes
1answer
354 views

KVM: Run a script when a guest is shutdown from within?

I am running KVM as virtualization engine. Is there a way to make QEMU/libvirt run a script on the host when a guest is shutdown from within (shutdown -h now)? I want to be able to run some custom ...
3
votes
2answers
9k views

conversion of a VMDK image with qemu-img failed with “error while reading sector 131072: Invalid argument”

I tried to convert a VMDK image found in a OVA file to the QCOW2 format with the qemu-img command but it failed with the error message qemu-img: error while reading sector 131072: Invalid argument ...
3
votes
2answers
155 views

Managing a QEMU guest from the host's CLI

Can I manage a QEMU guest from the host's CLI? I'm coming from Xen and I liked the xm command. I'd like to shutdown the guest, attach PCI devices to it and so on. Is there a way? There's the QEMU ...
3
votes
1answer
491 views

libvirtd kvm networking on Centos5.4

I've got KVM installed on CentOS 5.4, and am attempting to set up a virtual network to allow each VM to communicate with services on the host, namely DHCP to allow PXE boot installations. I'm having ...
3
votes
2answers
3k views

qemu-kvm/virsh: No network connectivity whilst using bridged networking

I'm having an issue with performing virtualisation via libvirt/qemu-kvm, in which my set up for bridged networking doesn't appear to be working correctly. I've followed every tutorial I can find and ...
3
votes
2answers
1k views

Can I run a KVM guest with a btrfs subvolume as file system?

I want to run a virtualized Debian stable KVM guest on a Debian stable host (to run untrusted stuff like Skype, Flash or eclipse with third-party plugins). Naturally host and guest will have many ...
3
votes
2answers
176 views

kvm process has too large a memory footprint on host

I'm using latest ubuntu quantal and start a kvm guest which should have 2048 MB of memory. Now after a few hours I can see that the kvm process of this guest is around 2700 MB, so 700 MB more than the ...
3
votes
2answers
208 views

virtual interface names in qemu/kvm

I have an image with a debian-squeeze installation and using that I created two overlay-images to boot two (nearly identical) virtual machines from. When I boot them up individually (connecting them ...
3
votes
2answers
1k views

How do I run a stable Windows XP kvm guest on Ubuntu 10.04?

I have three Windows XP guests running on a recently upgraded 64-bit Ubuntu 10.04 system. Occasionally (on the order of once every few days), one of the guests will become non-responsive and the kvm ...
3
votes
1answer
607 views

qemu with tun virtual networking issues

I'm trying to setup a virtual networking environment using open-wrt qemu and vde2 The script to boot two qemu instances and conenct them together is the following ...
2
votes
3answers
4k views

Is there a way to determine which virtual interface belongs to a virtual machine in a kvm host?

I'm using qemu/kvm whith bridged networking. In the host machine there are several "vnetX" network interfaces without IP. I'm looking for a way to know which vnetX belong to a virtual machine. I ...
2
votes
2answers
1k views

Windows guest on KVM/Qemu suffers horrible key lag

Host OS is Arch Linux with the following versions:- qemu 2.1.0-2 libvirt 1.2.7-1 linux 3.15.8-1 Guest OS is Windows 7 64-bit. This problem did not exist when I first created this VM and started ...
2
votes
1answer
16k views

'Unrecognised disc label' - when using parted with qemu images

I have a Linux from scratch LiveCD running on qemu vm. I'm using this command to create a hda disc for qemu: qemu-img.exe create -f qcow2 base-linux.img 5G Then I run my vm: qemu.exe -m 1024 ...
2
votes
3answers
4k views

Convert directory to QEMU/KVM virtual disk image

I have a directory filled with data at /var/backups/disk1 that I want to convert into a virtual disk image which I'll then be able to boot using QEMU or KVM (the directory contains the file system for ...
2
votes
2answers
2k views

Qemu: issues with bridged networking (Linux host, OpenBSD guest)

I have a computer running Linux. It has qemu installed. It has a bridge interface br0 configured with the following settings: IP: 10.1.1.1 Netmask: 255.255.255.0 There is also a tap0 interface that ...
2
votes
2answers
3k views

How to start qemu directly in the console (*not* in curses or SDL)

I seem to recall being able to start qemu with only the terminal emulator output, with the graphic window disabled. And here I don't mean with the ncurses interface, that one is nice, but I want the ...
2
votes
1answer
564 views

How to connect a virtual NIC in one QEMU-KVM instance to a virtual NIC in another QEMU-KVM instance without a bridge

Is there a way to connect a Virtual NIC one QEMU-KVM instance to a Virtual NIC on another QEMU-KVM instance. I want to be able to do this efficiently and it may be possible that the 2 instances could ...
2
votes
1answer
1k views

Set Mac Address in QEMU/KVM properties file

I'm trying to set the mac address for my virtual machine in the virtual machine properties file. The properties file '102.conf' currently looks like this: name: vm1.mydomain.com bootdisk: ide0 ...
2
votes
1answer
2k views

qemu-system-x86_64w.exe : could not open disk image D:\img.img: Permission denied

I'm trying to use qemu on Windows (8), because I have to emulate an USB mass storage device (VirtualBox still doesn't handle USB3 which my computer only have .. and if I could have qemu working it ...
2
votes
1answer
133 views

Install Windows with QEMU

I want to understand if it is possible to install Windows from Qemu to a physical HDD. I was trying to do that by doing something like this: qemu-system-x64 -m1024 -vnc :1 -hda /dev/sda -cdrom ...
2
votes
2answers
3k views

qemu-img: Could not open $FILE

I received a single-file VMDK from a vendor that has a virtual appliance for a particular product I'm interested in evaluating. We run a KVM solution (Proxmox) so I tried converting the file but on ...
2
votes
1answer
273 views

Guest Access in QEMU-KVM

I am having trouble in accessing my Guest OS running on QEMU-KVM. However, I noticed that the Guest OS is capable of accessing Host OS easily thru telnet; basically every IP address appear in ifconfig ...
2
votes
1answer
779 views

libvirt, qemu, reboot hook

Is it possible to detect that the guest VM has rebooted and perform an action using libvirt / qemu? The hooks here only support the "start" and "stop" events. I would like to detect if my VM has ...
2
votes
2answers
444 views

Internet Forwarding With Qemu?

I'm using kvm and qemu to run a windows virtual machine, but I'm trying to get internet on that machine. I've been reading about all this bridging and stuff that is done to do that, but I was ...
2
votes
2answers
64 views

How to measure boot time of a VM from host machine?

On both Guest machine and host machine, I am using Ubuntu 12.04. As a hypervisor I am using KVM. I want to perform some experiments related to boot-storm and I have created all other scripts to ...
2
votes
0answers
145 views

libvirt / kvm guests take very long time to start after host reboot

Host system is CentOS 6.5 x86_64. I have setup an Ubuntu guest by following this wiki. The guest works, but: if I reboot the host, it takes a very long time (about 30 minutes on the last reboot) ...
2
votes
0answers
117 views

LibVirt (QEMU) Shutting down from inside guest

I am currently running LibVirt with Qemu on Debian Wheezy: Versions: libvirtd (libvirt) 1.2.4 qemu-x86_64 version 2.0.0 (Debian 2.0.0+dfsg-4~bpo70+1), Copyright (c) 2003-2008 Fabrice Bellard It's ...