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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15
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2answers
8k 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 ...
13
votes
2answers
1k 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 ...
12
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4answers
23k 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 ...
10
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 ...
8
votes
2answers
6k 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 ...
7
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 ...
7
votes
2answers
5k 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 ...
6
votes
1answer
991 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 ...
5
votes
2answers
136 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 ...
5
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 ...
5
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2answers
8k 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. ...
5
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 ...
5
votes
1answer
556 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 ...
5
votes
2answers
2k 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 ...
5
votes
1answer
915 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 ...
4
votes
2answers
684 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
0answers
557 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
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 ...
3
votes
1answer
272 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
7k 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
759 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
488 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
114 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/*' ...
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 ...
2
votes
3answers
3k 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
469 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
59 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 ...
2
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: ...
2
votes
1answer
13k 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
2answers
148 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 ...
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
1answer
502 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
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 ...
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
2answers
769 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 ...
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
130 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
153 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 ...
2
votes
2answers
2k 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
2answers
196 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 ...
2
votes
1answer
720 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
400 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
0answers
77 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 ...
2
votes
0answers
178 views

Why is qemu issuing a DHCP discover after it receives a DHCP offer

I'm having some trouble seting up network on qemu. I'm trying the easy option (user). The qemu command I run is this: ./qemu-xilinx/arm-softmmu/qemu-system-arm \ -M xilinx-zynq-a9 -m 1024 ...
2
votes
0answers
613 views

virtualbox to qemu but results in no bootable device qemu

I use vagrant to create my development vm. I exported the vmdk to vdi, and then convert the vdi to img. cd virtualbox_dir/test_vm VBoxManage clonehd test_vm.vmdk raw.vdi 0% ..... 100% qemu-img ...
2
votes
1answer
530 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
1answer
471 views

Installing and running a guest OS on KVM-qemu with only serial console access

I am trying to installing a bsd distro with virt-installer. With a Linux distro I used this: virt-install -n debian -r 1024 --vcpus=1 --accelerate -v --disk ...
2
votes
1answer
231 views

KVM QEMU looses USB devices

I have a KVM Qemu setup. I'm mapping a USB device to a VM running windows vista. I get the device mapped, and all is well for some time. Suddenly the device disappears in Vista. If I do "lsusb" in ...
1
vote
2answers
173 views

How to delete the MBR (Master boot record) out of an image file?

I have a QEMU image myserver.img that is about 20GiB. The file serves as a "virtual" hard disk for the server. Now the first 512 bytes contain the MBR, and I am trying to overwrite those bytes with ...
1
vote
1answer
174 views

Is it possible to run Windows as a Xen VM without VT, using Qemu-dm?

Is it possible to run windows as a virtual machine under Xen using qemu-dm? If so, how can it be done? Since Xen without VT technology supports only para-virtualization, can qemu-dm, the emulator ...