QEMU is a free and open-source hypervisor that performs hardware virtualization by emulating CPUs through dynamic binary translation and providing device models. This allows it to run unmodified guest operating systems. It can be used to create virtual machines similarly to VMWare, VirtualBox, KVM, and Xen. QEMU also supports emulating different CPU architectures and can save and restore the state of a virtual machine.

1. QEMU

2. Introduction
➢ QEMU short for Quick Emulator.
➢ QEMU creates a virtual machine, similar to
VMWare, Virtualbox, KVM, and Xen.
➢ It allows you to run one operating system from
within another operating system.
➢ The operating systems can be the same ones,
or different.
➢ Your memory resources will be divided between
your native (host) OS and your virtual machine
(guest) OS.

3. ➢ QEMU is a free and open-source hosted
hypervisor that performs hardware virtualization.
➢ It emulates CPUs through dynamic binary
translation and provides a set of device models,
enabling it to run a variety of unmodified guest
operating systems.
➢ It also can be used together with KVM in order
to run virtual machines at near-native speed.
➢ QEMU can also be used purely for CPU
emulation for user-level processes, allowing
applications compiled for one architecture to be
run on another.

4. Operating modes
➢ User-mode emulation
➢ System-mode emulation

5. User-mode emulation
➢ In this mode QEMU runs single Linux
programs that were compiled for a different
instruction set.
➢ 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.

6. System-mode 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, windows.
➢ It supports emulating several instruction sets,
including x86, 32-bit ARMv7, ARMv8.

7. Features
➢ QEMU can save and restore the state of the
virtual machine with all programs running.
➢ Guest operating-systems do not need
patching in order to run inside QEMU.
➢ QEMU supports the emulation of various
architectures, including:
IA-32 (x86) PCs
x86-64 PCs
ARM development boards

8. QEMU Internals
➢ Portable dynamic translation
➢ Condition code optimisations
➢ CPU state optimisations
➢ Translation cache
➢ Direct block chaining
➢ Self-modifying code and translated code invalidation
➢ Exception support
➢ MMU emulation
➢ Device emulation
➢ Hardware interrupts

9. Supported disk image formats
➢ OS X Universal Disk Image Format (.dmg) – Read-only
➢ Bochs – Read-only
➢ Linux cloop – Read-only
➢ Parallels disk image (.hdd, .hds) – Read-only
➢ QEMU copy-on-write (.qcow2, qed, .qcow, cow)
➢ VirtualBox Virtual Disk Image (.vdi)
➢ Virtual PC Virtual Hard Disk (.vhd)
➢ Virtual VFAT
➢ VMware Virtual Machine Disk (.vmdk)
➢ Raw images (.img) that contain sector-by-sector contents of a
disk.
➢ CD/DVD images (.iso) that contain sector-by-sector contents
of an optical disk.