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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.

QEMU has two operating modes:

  • User mode emulation

In this mode QEMU runs single Linux or Darwin/Mac OS X programs that were compiled for a different CPU. System calls are thunked for endianness and for 32/64 bit mismatches. Fast cross-compilation and cross-debugging are the main targets for user-mode emulation.

  • Computer emulation

In this mode QEMU emulates a full computer system, including peripherals. It can be used to provide virtual hosting of several virtual computers on a single computer. QEMU can boot many guest operating systems, including Linux, Solaris, Microsoft Windows, DOS, and BSD 1; it supports emulating several hardware platforms, including x86, x86-64, ARM, Alpha, ETRAX CRIS, MIPS, MicroBlaze, PowerPC and SPARC.

Source: wikipedia

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WARNING KVM acceleration not available, using 'qemu'

Running debian (Linux Rick 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1+deb8u6 (2015-11-09) x86_64 GNU/Linux) Looking at my cpuinfo I can see I have vmx support: flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush…
red888
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Backup of running KVM qcow2 VPS

I want a robust method of taking backup of KVM VPS of qcow2 file, while running. After searching for a long time I found that we can use rsync for live backup. I used following command for rsync: rsync -avh /vms/base.qcow2 /backup/backup.qcow2 It…
Bosco D'mello
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How can I change Qemu KVM machine architecture from 440fx to q35 with virsh edit or virt-manager

Still trying to get GPU passthrough working and decided to change machine type from older 440fx to q35 ie pc-q35 but if I do virsh edit on the config it refuse to save saying "PCI Bridges not supported"... by current qemu binary. What do I need to…
htfree
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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 "Booting from Hard Disk". I've already managed to import…
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How to add virtual storage as SSD in KVM

Being previously a VirtualBox user, I moved to KVM(QEMU/libvirt or whatever it's called) recently. I know that in VirtualBox, when you add a new storage device to the VM, there is a checkbox labeled Solid-state Drive, if checked, the guest system…
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Why can't QEMU allocate the memory if the Linux caches are too big?

If I use my machine [Ubuntu 16.04 64 bit, kernel 4.4] for a while, QEMU needs the kernel caches to be dropped, otherwise, it won't manage to allocate the RAM. Why does it happen? This is a sample run: ~$ free -m total used …
Marcus
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How to forward a port from guest to host in qemu (kvm)

Is it possible, and how, to forward a port from guest to host in qemu/kvm? Note do I mean (out of) from guest to host, and not from host into guest (that's widely documented). I think I'm looking for the "opposite" of hostfwd/redir.. Like I use &…
vorburger
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Difference between qemu-kvm, qemu-system-x86_64, qemu-x86_64

For new features, I recently updated qemu-kvm 1.5.3 to qemu 2.5.0, but I saw several qemu binaries, /usr/local/bin/qemu-x86_64 and /usr/local/bin/qemu-system-x86_64. It seems qemu-system-x86_64 is the emulator program, since libvirt won't recognize…
dotslashlu
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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 DRBD 8.3.11 qemu-kvm…
PythonLearner
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Vagrant (Virtualbox) host-only multiple node networking issue

I'm trying to use a multi-VM vagrant environment as a testbed for deploying OpenStack, and I've run into a networking problem with trying to communicate from one VM, to a VM-inside-of-a-VM. I have two Vagrant nodes, a cloud controller node and a…
Lorin Hochstein
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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 . Still, it attempts to boot from the harddrive instead of the cdrom. I know I have an ISO image loaded on the CD-ROM virtual…
Belmin Fernandez
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QEMU - incorrect real disk size of a virtual drive

df and ls report different sizes on my host machine because of the difference between the allocated size and the amount of space that's actually used in the EXT4 filesystem. The problem is that both report the wrong size. qemu-img also doesn't…
user3125731
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How to repair a broken-resized qcow2 disk image for libvirt/kvm?

Today I wanted to increase the size of a VM, so I did what I always do (have done it before): qemu-img resize diskimage.qcow2 +22GB Then the file broke and the VM does not start any more. I tried booting the VM from CD to adjust partitioning but…
Ned64
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KVM / QEMU: connect to VM without GUI

Short Version (Solution is below): I have a Windows PC. I have a Debian server (without desktop environment). I have a Ubuntu VM running on Debian server via KVM/QEMU. Question: How can I connect to Ubuntu VM and start the installation process? Long…
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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 command: virt-install --connect qemu:///system \ …
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