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Virtualization Guide
  1. Preface
  2. I Introduction
    1. 1 Virtualization technology
    2. 2 Virtualization scenarios
    3. 3 Introduction to Xen virtualization
    4. 4 Introduction to KVM virtualization
    5. 5 Virtualization tools
    6. 6 Installation of virtualization components
  3. II Managing virtual machines with libvirt
    1. 7 Starting and stopping libvirtd
    2. 8 Preparing the VM Host Server
    3. 9 Guest installation
    4. 10 Basic VM Guest management
    5. 11 Connecting and authorizing
    6. 12 Advanced storage topics
    7. 13 Configuring virtual machines with Virtual Machine Manager
    8. 14 Configuring virtual machines with virsh
    9. 15 Managing virtual machines with Vagrant
    10. 16 Xen to KVM migration guide
  4. III Hypervisor-independent features
    1. 17 Disk cache modes
    2. 18 VM Guest clock settings
    3. 19 libguestfs
    4. 20 QEMU guest agent
    5. 21 Software TPM emulator
  5. IV Managing virtual machines with Xen
    1. 22 Setting up a virtual machine host
    2. 23 Virtual networking
    3. 24 Managing a virtualization environment
    4. 25 Block devices in Xen
    5. 26 Virtualization: configuration options and settings
    6. 27 Administrative tasks
    7. 28 XenStore: configuration database shared between domains
    8. 29 Xen as a high-availability virtualization host
    9. 30 Xen: converting a paravirtual (PV) guest into a fully virtual (FV/HVM) guest
  6. V Managing virtual machines with QEMU
    1. 31 QEMU overview
    2. 32 Setting up a KVM VM Host Server
    3. 33 Guest installation
    4. 34 Running virtual machines with qemu-system-ARCH
    5. 35 Virtual machine administration using QEMU monitor
  7. VI Troubleshooting
    1. 36 Integrated help and package documentation
    2. 37 Gathering system information and logs
  8. Glossary
  9. A Configuring GPU Pass-Through for NVIDIA cards
  10. B GNU licenses
Applies to openSUSE Leap 15.3

31 QEMU overview Edit source

QEMU is a fast, cross-platform open source machine emulator which can emulate many hardware architectures. QEMU lets you run a complete unmodified operating system (VM Guest) on top of your existing system (VM Host Server). You can also use QEMU for debugging purposes—you can easily stop your running virtual machine, inspect its state, and save and restore it later.

QEMU mainly consists of the following parts:

  • Processor emulator.

  • Emulated devices, such as graphic card, network card, hard disks, or mouse.

  • Generic devices used to connect the emulated devices to the related host devices.

  • Debugger.

  • User interface used to interact with the emulator.

QEMU is central to KVM and Xen Virtualization, where it provides the general machine emulation. Xen's usage of QEMU is somewhat hidden from the user, while KVM's usage exposes most QEMU features transparently. If the VM Guest hardware architecture is the same as the VM Host Server's architecture, QEMU can take advantage of the KVM acceleration (SUSE only supports QEMU with the KVM acceleration loaded).

Apart from providing a core virtualization infrastructure and processor-specific drivers, QEMU also provides an architecture-specific user space program for managing VM Guests. Depending on the architecture this program is one of:

  • qemu-system-i386

  • qemu-system-s390x

  • qemu-system-x86_64

  • qemu-system-aarch64

In the following this command is called qemu-system-ARCH; in examples the qemu-system-x86_64 command is used.

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