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.