Include auth credentials in 'info vnc' ("Daniel P. Berrange")

[mirror_qemu.git] / qemu-doc.texi

\input texinfo @c -*- texinfo -*-
@c %**start of header
@setfilename qemu-doc.info
@settitle QEMU Emulator User Documentation
@exampleindent 0
@paragraphindent 0
@c %**end of header

@iftex
@titlepage
@sp 7
@center @titlefont{QEMU Emulator}
@sp 1
@center @titlefont{User Documentation}
@sp 3
@end titlepage
@end iftex

@ifnottex
@node Top
@top

@menu
* Introduction::
* Installation::
* QEMU PC System emulator::
* QEMU System emulator for non PC targets::
* QEMU User space emulator::
* compilation:: Compilation from the sources
* Index::
@end menu
@end ifnottex

@contents

@node Introduction
@chapter Introduction

@menu
* intro_features:: Features
@end menu

@node intro_features
@section Features

QEMU is a FAST! processor emulator using dynamic translation to
achieve good emulation speed.

QEMU has two operating modes:

@itemize @minus

@item
Full system emulation. In this mode, QEMU emulates a full system (for
example a PC), including one or several processors and various
peripherals. It can be used to launch different Operating Systems
without rebooting the PC or to debug system code.

@item
User mode emulation. In this mode, QEMU can launch
processes compiled for one CPU on another CPU. It can be used to
launch the Wine Windows API emulator (@url{http://www.winehq.org}) or
to ease cross-compilation and cross-debugging.

@end itemize

QEMU can run without an host kernel driver and yet gives acceptable
performance.

For system emulation, the following hardware targets are supported:
@itemize
@item PC (x86 or x86_64 processor)
@item ISA PC (old style PC without PCI bus)
@item PREP (PowerPC processor)
@item G3 Beige PowerMac (PowerPC processor)
@item Mac99 PowerMac (PowerPC processor, in progress)
@item Sun4m/Sun4c/Sun4d (32-bit Sparc processor)
@item Sun4u/Sun4v (64-bit Sparc processor, in progress)
@item Malta board (32-bit and 64-bit MIPS processors)
@item MIPS Magnum (64-bit MIPS processor)
@item ARM Integrator/CP (ARM)
@item ARM Versatile baseboard (ARM)
@item ARM RealView Emulation baseboard (ARM)
@item Spitz, Akita, Borzoi, Terrier and Tosa PDAs (PXA270 processor)
@item Luminary Micro LM3S811EVB (ARM Cortex-M3)
@item Luminary Micro LM3S6965EVB (ARM Cortex-M3)
@item Freescale MCF5208EVB (ColdFire V2).
@item Arnewsh MCF5206 evaluation board (ColdFire V2).
@item Palm Tungsten|E PDA (OMAP310 processor)
@item N800 and N810 tablets (OMAP2420 processor)
@item MusicPal (MV88W8618 ARM processor)
@item Gumstix "Connex" and "Verdex" motherboards (PXA255/270).
@item Siemens SX1 smartphone (OMAP310 processor)
@end itemize

For user emulation, x86, PowerPC, ARM, 32-bit MIPS, Sparc32/64 and ColdFire(m68k) CPUs are supported.

@node Installation
@chapter Installation

If you want to compile QEMU yourself, see @ref{compilation}.

@menu
* install_linux::   Linux
* install_windows:: Windows
* install_mac::     Macintosh
@end menu

@node install_linux
@section Linux

If a precompiled package is available for your distribution - you just
have to install it. Otherwise, see @ref{compilation}.

@node install_windows
@section Windows

Download the experimental binary installer at
@url{http://www.free.oszoo.org/@/download.html}.

@node install_mac
@section Mac OS X

Download the experimental binary installer at
@url{http://www.free.oszoo.org/@/download.html}.

@node QEMU PC System emulator
@chapter QEMU PC System emulator

@menu
* pcsys_introduction:: Introduction
* pcsys_quickstart::   Quick Start
* sec_invocation::     Invocation
* pcsys_keys::         Keys
* pcsys_monitor::      QEMU Monitor
* disk_images::        Disk Images
* pcsys_network::      Network emulation
* direct_linux_boot::  Direct Linux Boot
* pcsys_usb::          USB emulation
* vnc_security::       VNC security
* gdb_usage::          GDB usage
* pcsys_os_specific::  Target OS specific information
@end menu

@node pcsys_introduction
@section Introduction

@c man begin DESCRIPTION

The QEMU PC System emulator simulates the
following peripherals:

@itemize @minus
@item
i440FX host PCI bridge and PIIX3 PCI to ISA bridge
@item
Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
extensions (hardware level, including all non standard modes).
@item
PS/2 mouse and keyboard
@item
2 PCI IDE interfaces with hard disk and CD-ROM support
@item
Floppy disk
@item
PCI/ISA PCI network adapters
@item
Serial ports
@item
Creative SoundBlaster 16 sound card
@item
ENSONIQ AudioPCI ES1370 sound card
@item
Intel 82801AA AC97 Audio compatible sound card
@item
Adlib(OPL2) - Yamaha YM3812 compatible chip
@item
Gravis Ultrasound GF1 sound card
@item
CS4231A compatible sound card
@item
PCI UHCI USB controller and a virtual USB hub.
@end itemize

SMP is supported with up to 255 CPUs.

Note that adlib, gus and cs4231a are only available when QEMU was
configured with --audio-card-list option containing the name(s) of
required card(s).

QEMU uses the PC BIOS from the Bochs project and the Plex86/Bochs LGPL
VGA BIOS.

QEMU uses YM3812 emulation by Tatsuyuki Satoh.

QEMU uses GUS emulation(GUSEMU32 @url{http://www.deinmeister.de/gusemu/})
by Tibor "TS" Schütz.

CS4231A is the chip used in Windows Sound System and GUSMAX products

@c man end

@node pcsys_quickstart
@section Quick Start

Download and uncompress the linux image (@file{linux.img}) and type:

@example
qemu linux.img
@end example

Linux should boot and give you a prompt.

@node sec_invocation
@section Invocation

@example
@c man begin SYNOPSIS
usage: qemu [options] [@var{disk_image}]
@c man end
@end example

@c man begin OPTIONS
@var{disk_image} is a raw hard disk image for IDE hard disk 0. Some
targets do not need a disk image.

General options:
@table @option
@item -h
Display help and exit

@item -M @var{machine}
Select the emulated @var{machine} (@code{-M ?} for list)

@item -cpu @var{model}
Select CPU model (-cpu ? for list and additional feature selection)

@item -smp @var{n}
Simulate an SMP system with @var{n} CPUs. On the PC target, up to 255
CPUs are supported. On Sparc32 target, Linux limits the number of usable CPUs
to 4.

@item -fda @var{file}
@item -fdb @var{file}
Use @var{file} as floppy disk 0/1 image (@pxref{disk_images}). You can
use the host floppy by using @file{/dev/fd0} as filename (@pxref{host_drives}).

@item -hda @var{file}
@item -hdb @var{file}
@item -hdc @var{file}
@item -hdd @var{file}
Use @var{file} as hard disk 0, 1, 2 or 3 image (@pxref{disk_images}).

@item -cdrom @var{file}
Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
@option{-cdrom} at the same time). You can use the host CD-ROM by
using @file{/dev/cdrom} as filename (@pxref{host_drives}).

@item -drive @var{option}[,@var{option}[,@var{option}[,...]]]

Define a new drive. Valid options are:

@table @code
@item file=@var{file}
This option defines which disk image (@pxref{disk_images}) to use with
this drive. If the filename contains comma, you must double it
(for instance, "file=my,,file" to use file "my,file").
@item if=@var{interface}
This option defines on which type on interface the drive is connected.
Available types are: ide, scsi, sd, mtd, floppy, pflash, virtio.
@item bus=@var{bus},unit=@var{unit}
These options define where is connected the drive by defining the bus number and
the unit id.
@item index=@var{index}
This option defines where is connected the drive by using an index in the list
of available connectors of a given interface type.
@item media=@var{media}
This option defines the type of the media: disk or cdrom.
@item cyls=@var{c},heads=@var{h},secs=@var{s}[,trans=@var{t}]
These options have the same definition as they have in @option{-hdachs}.
@item snapshot=@var{snapshot}
@var{snapshot} is "on" or "off" and allows to enable snapshot for given drive (see @option{-snapshot}).
@item cache=@var{cache}
@var{cache} is "none", "writeback", or "writethrough" and controls how the host cache is used to access block data.
@item format=@var{format}
Specify which disk @var{format} will be used rather than detecting
the format.  Can be used to specifiy format=raw to avoid interpreting
an untrusted format header.
@item serial=@var{serial}
This option specifies the serial number to assign to the device.
@end table

By default, writethrough caching is used for all block device.  This means that
the host page cache will be used to read and write data but write notification
will be sent to the guest only when the data has been reported as written by
the storage subsystem.

Writeback caching will report data writes as completed as soon as the data is
present in the host page cache.  This is safe as long as you trust your host.
If your host crashes or loses power, then the guest may experience data
corruption.  When using the @option{-snapshot} option, writeback caching is
used by default.

The host page can be avoided entirely with @option{cache=none}.  This will
attempt to do disk IO directly to the guests memory.  QEMU may still perform
an internal copy of the data.

Some block drivers perform badly with @option{cache=writethrough}, most notably,
qcow2.  If performance is more important than correctness,
@option{cache=writeback} should be used with qcow2.  By default, if no explicit
caching is specified for a qcow2 disk image, @option{cache=writeback} will be
used.  For all other disk types, @option{cache=writethrough} is the default.

Instead of @option{-cdrom} you can use:
@example
qemu -drive file=file,index=2,media=cdrom
@end example

Instead of @option{-hda}, @option{-hdb}, @option{-hdc}, @option{-hdd}, you can
use:
@example
qemu -drive file=file,index=0,media=disk
qemu -drive file=file,index=1,media=disk
qemu -drive file=file,index=2,media=disk
qemu -drive file=file,index=3,media=disk
@end example

You can connect a CDROM to the slave of ide0:
@example
qemu -drive file=file,if=ide,index=1,media=cdrom
@end example

If you don't specify the "file=" argument, you define an empty drive:
@example
qemu -drive if=ide,index=1,media=cdrom
@end example

You can connect a SCSI disk with unit ID 6 on the bus #0:
@example
qemu -drive file=file,if=scsi,bus=0,unit=6
@end example

Instead of @option{-fda}, @option{-fdb}, you can use:
@example
qemu -drive file=file,index=0,if=floppy
qemu -drive file=file,index=1,if=floppy
@end example

By default, @var{interface} is "ide" and @var{index} is automatically
incremented:
@example
qemu -drive file=a -drive file=b"
@end example
is interpreted like:
@example
qemu -hda a -hdb b
@end example

@item -mtdblock file
Use 'file' as on-board Flash memory image.

@item -sd file
Use 'file' as SecureDigital card image.

@item -pflash file
Use 'file' as a parallel flash image.

@item -boot [a|c|d|n]
Boot on floppy (a), hard disk (c), CD-ROM (d), or Etherboot (n). Hard disk boot
is the default.

@item -snapshot
Write to temporary files instead of disk image files. In this case,
the raw disk image you use is not written back. You can however force
the write back by pressing @key{C-a s} (@pxref{disk_images}).

@item -m @var{megs}
Set virtual RAM size to @var{megs} megabytes. Default is 128 MiB.  Optionally,
a suffix of ``M'' or ``G'' can be used to signify a value in megabytes or
gigabytes respectively.

@item -k @var{language}

Use keyboard layout @var{language} (for example @code{fr} for
French). This option is only needed where it is not easy to get raw PC
keycodes (e.g. on Macs, with some X11 servers or with a VNC
display). You don't normally need to use it on PC/Linux or PC/Windows
hosts.

The available layouts are:
@example
ar  de-ch  es  fo     fr-ca  hu  ja  mk     no  pt-br  sv
da  en-gb  et  fr     fr-ch  is  lt  nl     pl  ru     th
de  en-us  fi  fr-be  hr     it  lv  nl-be  pt  sl     tr
@end example

The default is @code{en-us}.

@item -audio-help

Will show the audio subsystem help: list of drivers, tunable
parameters.

@item -soundhw @var{card1}[,@var{card2},...] or -soundhw all

Enable audio and selected sound hardware. Use ? to print all
available sound hardware.

@example
qemu -soundhw sb16,adlib disk.img
qemu -soundhw es1370 disk.img
qemu -soundhw ac97 disk.img
qemu -soundhw all disk.img
qemu -soundhw ?
@end example

Note that Linux's i810_audio OSS kernel (for AC97) module might
require manually specifying clocking.

@example
modprobe i810_audio clocking=48000
@end example

@end table

USB options:
@table @option

@item -usb
Enable the USB driver (will be the default soon)

@item -usbdevice @var{devname}
Add the USB device @var{devname}. @xref{usb_devices}.

@table @code

@item mouse
Virtual Mouse. This will override the PS/2 mouse emulation when activated.

@item tablet
Pointer device that uses absolute coordinates (like a touchscreen). This
means qemu is able to report the mouse position without having to grab the
mouse. Also overrides the PS/2 mouse emulation when activated.

@item disk:[format=@var{format}]:file
Mass storage device based on file. The optional @var{format} argument
will be used rather than detecting the format. Can be used to specifiy
format=raw to avoid interpreting an untrusted format header.

@item host:bus.addr
Pass through the host device identified by bus.addr (Linux only).

@item host:vendor_id:product_id
Pass through the host device identified by vendor_id:product_id (Linux only).

@item serial:[vendorid=@var{vendor_id}][,productid=@var{product_id}]:@var{dev}
Serial converter to host character device @var{dev}, see @code{-serial} for the
available devices.

@item braille
Braille device.  This will use BrlAPI to display the braille output on a real
or fake device.

@item net:options
Network adapter that supports CDC ethernet and RNDIS protocols.

@end table

@item -name @var{name}
Sets the @var{name} of the guest.
This name will be displayed in the SDL window caption.
The @var{name} will also be used for the VNC server.

@item -uuid @var{uuid}
Set system UUID.

@end table

Display options:
@table @option

@item -nographic

Normally, QEMU uses SDL to display the VGA output. With this option,
you can totally disable graphical output so that QEMU is a simple
command line application. The emulated serial port is redirected on
the console. Therefore, you can still use QEMU to debug a Linux kernel
with a serial console.

@item -curses

Normally, QEMU uses SDL to display the VGA output.  With this option,
QEMU can display the VGA output when in text mode using a 
curses/ncurses interface.  Nothing is displayed in graphical mode.

@item -no-frame

Do not use decorations for SDL windows and start them using the whole
available screen space. This makes the using QEMU in a dedicated desktop
workspace more convenient.

@item -alt-grab

Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt).

@item -no-quit

Disable SDL window close capability.

@item -sdl

Enable SDL.

@item -portrait

Rotate graphical output 90 deg left (only PXA LCD).

@item -vga @var{type}
Select type of VGA card to emulate. Valid values for @var{type} are
@table @code
@item cirrus
Cirrus Logic GD5446 Video card. All Windows versions starting from
Windows 95 should recognize and use this graphic card. For optimal
performances, use 16 bit color depth in the guest and the host OS.
(This one is the default)
@item std
Standard VGA card with Bochs VBE extensions.  If your guest OS
supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if you want
to use high resolution modes (>= 1280x1024x16) then you should use
this option.
@item vmware
VMWare SVGA-II compatible adapter. Use it if you have sufficiently
recent XFree86/XOrg server or Windows guest with a driver for this
card.
@item none
Disable VGA card.
@end table

@item -full-screen
Start in full screen.

@item -vnc @var{display}[,@var{option}[,@var{option}[,...]]]

Normally, QEMU uses SDL to display the VGA output.  With this option,
you can have QEMU listen on VNC display @var{display} and redirect the VGA
display over the VNC session.  It is very useful to enable the usb
tablet device when using this option (option @option{-usbdevice
tablet}). When using the VNC display, you must use the @option{-k}
parameter to set the keyboard layout if you are not using en-us. Valid
syntax for the @var{display} is

@table @code

@item @var{host}:@var{d}

TCP connections will only be allowed from @var{host} on display @var{d}.
By convention the TCP port is 5900+@var{d}. Optionally, @var{host} can
be omitted in which case the server will accept connections from any host.

@item @code{unix}:@var{path}

Connections will be allowed over UNIX domain sockets where @var{path} is the
location of a unix socket to listen for connections on.

@item none

VNC is initialized but not started. The monitor @code{change} command
can be used to later start the VNC server.

@end table

Following the @var{display} value there may be one or more @var{option} flags
separated by commas. Valid options are

@table @code

@item reverse

Connect to a listening VNC client via a ``reverse'' connection. The
client is specified by the @var{display}. For reverse network
connections (@var{host}:@var{d},@code{reverse}), the @var{d} argument
is a TCP port number, not a display number.

@item password

Require that password based authentication is used for client connections.
The password must be set separately using the @code{change} command in the
@ref{pcsys_monitor}

@item tls

Require that client use TLS when communicating with the VNC server. This
uses anonymous TLS credentials so is susceptible to a man-in-the-middle
attack. It is recommended that this option be combined with either the
@var{x509} or @var{x509verify} options.

@item x509=@var{/path/to/certificate/dir}

Valid if @option{tls} is specified. Require that x509 credentials are used
for negotiating the TLS session. The server will send its x509 certificate
to the client. It is recommended that a password be set on the VNC server
to provide authentication of the client when this is used. The path following
this option specifies where the x509 certificates are to be loaded from.
See the @ref{vnc_security} section for details on generating certificates.

@item x509verify=@var{/path/to/certificate/dir}

Valid if @option{tls} is specified. Require that x509 credentials are used
for negotiating the TLS session. The server will send its x509 certificate
to the client, and request that the client send its own x509 certificate.
The server will validate the client's certificate against the CA certificate,
and reject clients when validation fails. If the certificate authority is
trusted, this is a sufficient authentication mechanism. You may still wish
to set a password on the VNC server as a second authentication layer. The
path following this option specifies where the x509 certificates are to
be loaded from. See the @ref{vnc_security} section for details on generating
certificates.

@item sasl

Require that the client use SASL to authenticate with the VNC server.
The exact choice of authentication method used is controlled from the
system / user's SASL configuration file for the 'qemu' service. This
is typically found in /etc/sasl2/qemu.conf. If running QEMU as an
unprivileged user, an environment variable SASL_CONF_PATH can be used
to make it search alternate locations for the service config.
While some SASL auth methods can also provide data encryption (eg GSSAPI),
it is recommended that SASL always be combined with the 'tls' and
'x509' settings to enable use of SSL and server certificates. This
ensures a data encryption preventing compromise of authentication
credentials. See the @ref{vnc_security} section for details on using
SASL authentication.

@end table

@end table

Network options:

@table @option

@item -net nic[,vlan=@var{n}][,macaddr=@var{addr}][,model=@var{type}][,name=@var{name}]
Create a new Network Interface Card and connect it to VLAN @var{n} (@var{n}
= 0 is the default). The NIC is an ne2k_pci by default on the PC
target. Optionally, the MAC address can be changed to @var{addr}
and a @var{name} can be assigned for use in monitor commands. If no
@option{-net} option is specified, a single NIC is created.
Qemu can emulate several different models of network card.
Valid values for @var{type} are
@code{i82551}, @code{i82557b}, @code{i82559er},
@code{ne2k_pci}, @code{ne2k_isa}, @code{pcnet}, @code{rtl8139},
@code{e1000}, @code{smc91c111}, @code{lance} and @code{mcf_fec}.
Not all devices are supported on all targets.  Use -net nic,model=?
for a list of available devices for your target.

@item -net user[,vlan=@var{n}][,hostname=@var{name}][,name=@var{name}]
Use the user mode network stack which requires no administrator
privilege to run.  @option{hostname=name} can be used to specify the client
hostname reported by the builtin DHCP server.

@item -net channel,@var{port}:@var{dev}
Forward @option{user} TCP connection to port @var{port} to character device @var{dev}

@item -net tap[,vlan=@var{n}][,name=@var{name}][,fd=@var{h}][,ifname=@var{name}][,script=@var{file}][,downscript=@var{dfile}]
Connect the host TAP network interface @var{name} to VLAN @var{n}, use
the network script @var{file} to configure it and the network script 
@var{dfile} to deconfigure it. If @var{name} is not provided, the OS 
automatically provides one. @option{fd}=@var{h} can be used to specify
the handle of an already opened host TAP interface. The default network 
configure script is @file{/etc/qemu-ifup} and the default network 
deconfigure script is @file{/etc/qemu-ifdown}. Use @option{script=no} 
or @option{downscript=no} to disable script execution. Example:

@example
qemu linux.img -net nic -net tap
@end example

More complicated example (two NICs, each one connected to a TAP device)
@example
qemu linux.img -net nic,vlan=0 -net tap,vlan=0,ifname=tap0 \
               -net nic,vlan=1 -net tap,vlan=1,ifname=tap1
@end example


@item -net socket[,vlan=@var{n}][,name=@var{name}][,fd=@var{h}][,listen=[@var{host}]:@var{port}][,connect=@var{host}:@var{port}]

Connect the VLAN @var{n} to a remote VLAN in another QEMU virtual
machine using a TCP socket connection. If @option{listen} is
specified, QEMU waits for incoming connections on @var{port}
(@var{host} is optional). @option{connect} is used to connect to
another QEMU instance using the @option{listen} option. @option{fd}=@var{h}
specifies an already opened TCP socket.

Example:
@example
# launch a first QEMU instance
qemu linux.img -net nic,macaddr=52:54:00:12:34:56 \
               -net socket,listen=:1234
# connect the VLAN 0 of this instance to the VLAN 0
# of the first instance
qemu linux.img -net nic,macaddr=52:54:00:12:34:57 \
               -net socket,connect=127.0.0.1:1234
@end example

@item -net socket[,vlan=@var{n}][,name=@var{name}][,fd=@var{h}][,mcast=@var{maddr}:@var{port}]

Create a VLAN @var{n} shared with another QEMU virtual
machines using a UDP multicast socket, effectively making a bus for
every QEMU with same multicast address @var{maddr} and @var{port}.
NOTES:
@enumerate
@item
Several QEMU can be running on different hosts and share same bus (assuming
correct multicast setup for these hosts).
@item
mcast support is compatible with User Mode Linux (argument @option{eth@var{N}=mcast}), see
@url{http://user-mode-linux.sf.net}.
@item
Use @option{fd=h} to specify an already opened UDP multicast socket.
@end enumerate

Example:
@example
# launch one QEMU instance
qemu linux.img -net nic,macaddr=52:54:00:12:34:56 \
               -net socket,mcast=230.0.0.1:1234
# launch another QEMU instance on same "bus"
qemu linux.img -net nic,macaddr=52:54:00:12:34:57 \
               -net socket,mcast=230.0.0.1:1234
# launch yet another QEMU instance on same "bus"
qemu linux.img -net nic,macaddr=52:54:00:12:34:58 \
               -net socket,mcast=230.0.0.1:1234
@end example

Example (User Mode Linux compat.):
@example
# launch QEMU instance (note mcast address selected
# is UML's default)
qemu linux.img -net nic,macaddr=52:54:00:12:34:56 \
               -net socket,mcast=239.192.168.1:1102
# launch UML
/path/to/linux ubd0=/path/to/root_fs eth0=mcast
@end example

@item -net vde[,vlan=@var{n}][,name=@var{name}][,sock=@var{socketpath}][,port=@var{n}][,group=@var{groupname}][,mode=@var{octalmode}]
Connect VLAN @var{n} to PORT @var{n} of a vde switch running on host and
listening for incoming connections on @var{socketpath}. Use GROUP @var{groupname}
and MODE @var{octalmode} to change default ownership and permissions for
communication port. This option is available only if QEMU has been compiled
with vde support enabled.

Example:
@example
# launch vde switch
vde_switch -F -sock /tmp/myswitch
# launch QEMU instance
qemu linux.img -net nic -net vde,sock=/tmp/myswitch
@end example

@item -net none
Indicate that no network devices should be configured. It is used to
override the default configuration (@option{-net nic -net user}) which
is activated if no @option{-net} options are provided.

@item -tftp @var{dir}
When using the user mode network stack, activate a built-in TFTP
server. The files in @var{dir} will be exposed as the root of a TFTP server.
The TFTP client on the guest must be configured in binary mode (use the command
@code{bin} of the Unix TFTP client). The host IP address on the guest is as
usual 10.0.2.2.

@item -bootp @var{file}
When using the user mode network stack, broadcast @var{file} as the BOOTP
filename.  In conjunction with @option{-tftp}, this can be used to network boot
a guest from a local directory.

Example (using pxelinux):
@example
qemu -hda linux.img -boot n -tftp /path/to/tftp/files -bootp /pxelinux.0
@end example

@item -smb @var{dir}
When using the user mode network stack, activate a built-in SMB
server so that Windows OSes can access to the host files in @file{@var{dir}}
transparently.

In the guest Windows OS, the line:
@example
10.0.2.4 smbserver
@end example
must be added in the file @file{C:\WINDOWS\LMHOSTS} (for windows 9x/Me)
or @file{C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS} (Windows NT/2000).

Then @file{@var{dir}} can be accessed in @file{\\smbserver\qemu}.

Note that a SAMBA server must be installed on the host OS in
@file{/usr/sbin/smbd}. QEMU was tested successfully with smbd version
2.2.7a from the Red Hat 9 and version 3.0.10-1.fc3 from Fedora Core 3.

@item -redir [tcp|udp]:@var{host-port}:[@var{guest-host}]:@var{guest-port}

When using the user mode network stack, redirect incoming TCP or UDP
connections to the host port @var{host-port} to the guest
@var{guest-host} on guest port @var{guest-port}. If @var{guest-host}
is not specified, its value is 10.0.2.15 (default address given by the
built-in DHCP server).

For example, to redirect host X11 connection from screen 1 to guest
screen 0, use the following:

@example
# on the host
qemu -redir tcp:6001::6000 [...]
# this host xterm should open in the guest X11 server
xterm -display :1
@end example

To redirect telnet connections from host port 5555 to telnet port on
the guest, use the following:

@example
# on the host
qemu -redir tcp:5555::23 [...]
telnet localhost 5555
@end example

Then when you use on the host @code{telnet localhost 5555}, you
connect to the guest telnet server.

@end table

Bluetooth(R) options:
@table @option

@item -bt hci[...]
Defines the function of the corresponding Bluetooth HCI.  -bt options
are matched with the HCIs present in the chosen machine type.  For
example when emulating a machine with only one HCI built into it, only
the first @code{-bt hci[...]} option is valid and defines the HCI's
logic.  The Transport Layer is decided by the machine type.  Currently
the machines @code{n800} and @code{n810} have one HCI and all other
machines have none.

@anchor{bt-hcis}
The following three types are recognized:

@table @code
@item -bt hci,null
(default) The corresponding Bluetooth HCI assumes no internal logic
and will not respond to any HCI commands or emit events.

@item -bt hci,host[:@var{id}]
(@code{bluez} only) The corresponding HCI passes commands / events
to / from the physical HCI identified by the name @var{id} (default:
@code{hci0}) on the computer running QEMU.  Only available on @code{bluez}
capable systems like Linux.

@item -bt hci[,vlan=@var{n}]
Add a virtual, standard HCI that will participate in the Bluetooth
scatternet @var{n} (default @code{0}).  Similarly to @option{-net}
VLANs, devices inside a bluetooth network @var{n} can only communicate
with other devices in the same network (scatternet).
@end table

@item -bt vhci[,vlan=@var{n}]
(Linux-host only) Create a HCI in scatternet @var{n} (default 0) attached
to the host bluetooth stack instead of to the emulated target.  This
allows the host and target machines to participate in a common scatternet
and communicate.  Requires the Linux @code{vhci} driver installed.  Can
be used as following:

@example
qemu [...OPTIONS...] -bt hci,vlan=5 -bt vhci,vlan=5
@end example

@item -bt device:@var{dev}[,vlan=@var{n}]
Emulate a bluetooth device @var{dev} and place it in network @var{n}
(default @code{0}).  QEMU can only emulate one type of bluetooth devices
currently:

@table @code
@item keyboard
Virtual wireless keyboard implementing the HIDP bluetooth profile.
@end table

@end table

i386 target only:

@table @option

@item -win2k-hack
Use it when installing Windows 2000 to avoid a disk full bug. After
Windows 2000 is installed, you no longer need this option (this option
slows down the IDE transfers).

@item -rtc-td-hack
Use it if you experience time drift problem in Windows with ACPI HAL.
This option will try to figure out how many timer interrupts were not
processed by the Windows guest and will re-inject them.

@item -no-fd-bootchk
Disable boot signature checking for floppy disks in Bochs BIOS. It may
be needed to boot from old floppy disks.

@item -no-acpi
Disable ACPI (Advanced Configuration and Power Interface) support. Use
it if your guest OS complains about ACPI problems (PC target machine
only).

@item -no-hpet
Disable HPET support.

@item -acpitable [sig=@var{str}][,rev=@var{n}][,oem_id=@var{str}][,oem_table_id=@var{str}][,oem_rev=@var{n}] [,asl_compiler_id=@var{str}][,asl_compiler_rev=@var{n}][,data=@var{file1}[:@var{file2}]...]
Add ACPI table with specified header fields and context from specified files.

@end table

Linux boot specific: When using these options, you can use a given
Linux kernel without installing it in the disk image. It can be useful
for easier testing of various kernels.

@table @option

@item -kernel @var{bzImage}
Use @var{bzImage} as kernel image.

@item -append @var{cmdline}
Use @var{cmdline} as kernel command line

@item -initrd @var{file}
Use @var{file} as initial ram disk.

@end table

Debug/Expert options:
@table @option

@item -serial @var{dev}
Redirect the virtual serial port to host character device
@var{dev}. The default device is @code{vc} in graphical mode and
@code{stdio} in non graphical mode.

This option can be used several times to simulate up to 4 serial
ports.

Use @code{-serial none} to disable all serial ports.

Available character devices are:
@table @code
@item vc[:WxH]
Virtual console. Optionally, a width and height can be given in pixel with
@example
vc:800x600
@end example
It is also possible to specify width or height in characters:
@example
vc:80Cx24C
@end example
@item pty
[Linux only] Pseudo TTY (a new PTY is automatically allocated)
@item none
No device is allocated.
@item null
void device
@item /dev/XXX
[Linux only] Use host tty, e.g. @file{/dev/ttyS0}. The host serial port
parameters are set according to the emulated ones.
@item /dev/parport@var{N}
[Linux only, parallel port only] Use host parallel port
@var{N}. Currently SPP and EPP parallel port features can be used.
@item file:@var{filename}
Write output to @var{filename}. No character can be read.
@item stdio
[Unix only] standard input/output
@item pipe:@var{filename}
name pipe @var{filename}
@item COM@var{n}
[Windows only] Use host serial port @var{n}
@item udp:[@var{remote_host}]:@var{remote_port}[@@[@var{src_ip}]:@var{src_port}]
This implements UDP Net Console.
When @var{remote_host} or @var{src_ip} are not specified
they default to @code{0.0.0.0}.
When not using a specified @var{src_port} a random port is automatically chosen.
@item msmouse
Three button serial mouse. Configure the guest to use Microsoft protocol.

If you just want a simple readonly console you can use @code{netcat} or
@code{nc}, by starting qemu with: @code{-serial udp::4555} and nc as:
@code{nc -u -l -p 4555}. Any time qemu writes something to that port it
will appear in the netconsole session.

If you plan to send characters back via netconsole or you want to stop
and start qemu a lot of times, you should have qemu use the same
source port each time by using something like @code{-serial
udp::4555@@:4556} to qemu. Another approach is to use a patched
version of netcat which can listen to a TCP port and send and receive
characters via udp.  If you have a patched version of netcat which
activates telnet remote echo and single char transfer, then you can
use the following options to step up a netcat redirector to allow
telnet on port 5555 to access the qemu port.
@table @code
@item Qemu Options:
-serial udp::4555@@:4556
@item netcat options:
-u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
@item telnet options:
localhost 5555
@end table


@item tcp:[@var{host}]:@var{port}[,@var{server}][,nowait][,nodelay]
The TCP Net Console has two modes of operation.  It can send the serial
I/O to a location or wait for a connection from a location.  By default
the TCP Net Console is sent to @var{host} at the @var{port}.  If you use
the @var{server} option QEMU will wait for a client socket application
to connect to the port before continuing, unless the @code{nowait}
option was specified.  The @code{nodelay} option disables the Nagle buffering
algorithm.  If @var{host} is omitted, 0.0.0.0 is assumed. Only
one TCP connection at a time is accepted. You can use @code{telnet} to
connect to the corresponding character device.
@table @code
@item Example to send tcp console to 192.168.0.2 port 4444
-serial tcp:192.168.0.2:4444
@item Example to listen and wait on port 4444 for connection
-serial tcp::4444,server
@item Example to not wait and listen on ip 192.168.0.100 port 4444
-serial tcp:192.168.0.100:4444,server,nowait
@end table

@item telnet:@var{host}:@var{port}[,server][,nowait][,nodelay]
The telnet protocol is used instead of raw tcp sockets.  The options
work the same as if you had specified @code{-serial tcp}.  The
difference is that the port acts like a telnet server or client using
telnet option negotiation.  This will also allow you to send the
MAGIC_SYSRQ sequence if you use a telnet that supports sending the break
sequence.  Typically in unix telnet you do it with Control-] and then
type "send break" followed by pressing the enter key.

@item unix:@var{path}[,server][,nowait]
A unix domain socket is used instead of a tcp socket.  The option works the
same as if you had specified @code{-serial tcp} except the unix domain socket
@var{path} is used for connections.

@item mon:@var{dev_string}
This is a special option to allow the monitor to be multiplexed onto
another serial port.  The monitor is accessed with key sequence of
@key{Control-a} and then pressing @key{c}. See monitor access
@ref{pcsys_keys} in the -nographic section for more keys.
@var{dev_string} should be any one of the serial devices specified
above.  An example to multiplex the monitor onto a telnet server
listening on port 4444 would be:
@table @code
@item -serial mon:telnet::4444,server,nowait
@end table

@item braille
Braille device.  This will use BrlAPI to display the braille output on a real
or fake device.

@end table

@item -parallel @var{dev}
Redirect the virtual parallel port to host device @var{dev} (same
devices as the serial port). On Linux hosts, @file{/dev/parportN} can
be used to use hardware devices connected on the corresponding host
parallel port.

This option can be used several times to simulate up to 3 parallel
ports.

Use @code{-parallel none} to disable all parallel ports.

@item -monitor @var{dev}
Redirect the monitor to host device @var{dev} (same devices as the
serial port).
The default device is @code{vc} in graphical mode and @code{stdio} in
non graphical mode.

@item -pidfile @var{file}
Store the QEMU process PID in @var{file}. It is useful if you launch QEMU
from a script.

@item -S
Do not start CPU at startup (you must type 'c' in the monitor).

@item -s
Wait gdb connection to port 1234 (@pxref{gdb_usage}).

@item -p @var{port}
Change gdb connection port.  @var{port} can be either a decimal number
to specify a TCP port, or a host device (same devices as the serial port).

@item -d
Output log in /tmp/qemu.log
@item -hdachs @var{c},@var{h},@var{s},[,@var{t}]
Force hard disk 0 physical geometry (1 <= @var{c} <= 16383, 1 <=
@var{h} <= 16, 1 <= @var{s} <= 63) and optionally force the BIOS
translation mode (@var{t}=none, lba or auto). Usually QEMU can guess
all those parameters. This option is useful for old MS-DOS disk
images.

@item -L  @var{path}
Set the directory for the BIOS, VGA BIOS and keymaps.

@item -bios @var{file}
Set the filename for the BIOS.

@item -kernel-kqemu
Enable KQEMU full virtualization (default is user mode only).

@item -no-kqemu
Disable KQEMU kernel module usage. KQEMU options are only available if
KQEMU support is enabled when compiling.

@item -enable-kvm
Enable KVM full virtualization support. This option is only available
if KVM support is enabled when compiling.

@item -no-reboot
Exit instead of rebooting.

@item -no-shutdown
Don't exit QEMU on guest shutdown, but instead only stop the emulation.
This allows for instance switching to monitor to commit changes to the
disk image.

@item -loadvm @var{file}
Start right away with a saved state (@code{loadvm} in monitor)

@item -daemonize
Daemonize the QEMU process after initialization.  QEMU will not detach from
standard IO until it is ready to receive connections on any of its devices.
This option is a useful way for external programs to launch QEMU without having
to cope with initialization race conditions.

@item -option-rom @var{file}
Load the contents of @var{file} as an option ROM.
This option is useful to load things like EtherBoot.

@item -clock @var{method}
Force the use of the given methods for timer alarm. To see what timers
are available use -clock ?.

@item -localtime
Set the real time clock to local time (the default is to UTC
time). This option is needed to have correct date in MS-DOS or
Windows.

@item -startdate @var{date}
Set the initial date of the real time clock. Valid formats for
@var{date} are: @code{now} or @code{2006-06-17T16:01:21} or
@code{2006-06-17}. The default value is @code{now}.

@item -icount [N|auto]
Enable virtual instruction counter.  The virtual cpu will execute one
instruction every 2^N ns of virtual time.  If @code{auto} is specified
then the virtual cpu speed will be automatically adjusted to keep virtual
time within a few seconds of real time.

Note that while this option can give deterministic behavior, it does not
provide cycle accurate emulation.  Modern CPUs contain superscalar out of
order cores with complex cache hierarchies.  The number of instructions
executed often has little or no correlation with actual performance.

@item -echr numeric_ascii_value
Change the escape character used for switching to the monitor when using
monitor and serial sharing.  The default is @code{0x01} when using the
@code{-nographic} option.  @code{0x01} is equal to pressing
@code{Control-a}.  You can select a different character from the ascii
control keys where 1 through 26 map to Control-a through Control-z.  For
instance you could use the either of the following to change the escape
character to Control-t.
@table @code
@item -echr 0x14
@item -echr 20
@end table

@item -chroot dir
Immediately before starting guest execution, chroot to the specified
directory.  Especially useful in combination with -runas.

@item -runas user
Immediately before starting guest execution, drop root privileges, switching
to the specified user.

@end table

@c man end

@node pcsys_keys
@section Keys

@c man begin OPTIONS

During the graphical emulation, you can use the following keys:
@table @key
@item Ctrl-Alt-f
Toggle full screen

@item Ctrl-Alt-n
Switch to virtual console 'n'. Standard console mappings are:
@table @emph
@item 1
Target system display
@item 2
Monitor
@item 3
Serial port
@end table

@item Ctrl-Alt
Toggle mouse and keyboard grab.
@end table

In the virtual consoles, you can use @key{Ctrl-Up}, @key{Ctrl-Down},
@key{Ctrl-PageUp} and @key{Ctrl-PageDown} to move in the back log.

During emulation, if you are using the @option{-nographic} option, use
@key{Ctrl-a h} to get terminal commands:

@table @key
@item Ctrl-a h
@item Ctrl-a ?
Print this help
@item Ctrl-a x
Exit emulator
@item Ctrl-a s
Save disk data back to file (if -snapshot)
@item Ctrl-a t
Toggle console timestamps
@item Ctrl-a b
Send break (magic sysrq in Linux)
@item Ctrl-a c
Switch between console and monitor
@item Ctrl-a Ctrl-a
Send Ctrl-a
@end table
@c man end

@ignore

@c man begin SEEALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
@c man end

@c man begin AUTHOR
Fabrice Bellard
@c man end

@end ignore

@node pcsys_monitor
@section QEMU Monitor

The QEMU monitor is used to give complex commands to the QEMU
emulator. You can use it to:

@itemize @minus

@item
Remove or insert removable media images
(such as CD-ROM or floppies).

@item
Freeze/unfreeze the Virtual Machine (VM) and save or restore its state
from a disk file.

@item Inspect the VM state without an external debugger.

@end itemize

@subsection Commands

The following commands are available:

@table @option

@item help or ? [@var{cmd}]
Show the help for all commands or just for command @var{cmd}.

@item commit
Commit changes to the disk images (if -snapshot is used).

@item info @var{subcommand}
Show various information about the system state.

@table @option
@item info version
show the version of QEMU
@item info network
show the various VLANs and the associated devices
@item info chardev
show the character devices
@item info block
show the block devices
@item info block
show block device statistics
@item info registers
show the cpu registers
@item info cpus
show infos for each CPU
@item info history
show the command line history
@item info irq
show the interrupts statistics (if available)
@item info pic
show i8259 (PIC) state
@item info pci
show emulated PCI device info
@item info tlb
show virtual to physical memory mappings (i386 only)
@item info mem
show the active virtual memory mappings (i386 only)
@item info hpet
show state of HPET (i386 only)
@item info kqemu
show KQEMU information
@item info kvm
show KVM information
@item info usb
show USB devices plugged on the virtual USB hub
@item info usbhost
show all USB host devices
@item info profile
show profiling information
@item info capture
show information about active capturing
@item info snapshots
show list of VM snapshots
@item info status
show the current VM status (running|paused)
@item info pcmcia
show guest PCMCIA status
@item info mice
show which guest mouse is receiving events
@item info vnc
show the vnc server status
@item info name
show the current VM name
@item info uuid
show the current VM UUID
@item info cpustats
show CPU statistics
@item info slirp
show SLIRP statistics (if available)
@item info migrate
show migration status
@item info balloon
show balloon information
@end table

@item q or quit
Quit the emulator.

@item eject [-f] @var{device}
Eject a removable medium (use -f to force it).

@item change @var{device} @var{setting}

Change the configuration of a device.

@table @option
@item change @var{diskdevice} @var{filename} [@var{format}]
Change the medium for a removable disk device to point to @var{filename}. eg

@example
(qemu) change ide1-cd0 /path/to/some.iso
@end example

@var{format} is optional.

@item change vnc @var{display},@var{options}
Change the configuration of the VNC server. The valid syntax for @var{display}
and @var{options} are described at @ref{sec_invocation}. eg

@example
(qemu) change vnc localhost:1
@end example

@item change vnc password [@var{password}]

Change the password associated with the VNC server. If the new password is not
supplied, the monitor will prompt for it to be entered. VNC passwords are only
significant up to 8 letters. eg

@example
(qemu) change vnc password
Password: ********
@end example

@end table

@item screendump @var{filename}
Save screen into PPM image @var{filename}.

@item logfile @var{filename}
Output logs to @var{filename}.

@item log @var{item1}[,...]
Activate logging of the specified items to @file{/tmp/qemu.log}.

@item savevm [@var{tag}|@var{id}]
Create a snapshot of the whole virtual machine. If @var{tag} is
provided, it is used as human readable identifier. If there is already
a snapshot with the same tag or ID, it is replaced. More info at
@ref{vm_snapshots}.

@item loadvm @var{tag}|@var{id}
Set the whole virtual machine to the snapshot identified by the tag
@var{tag} or the unique snapshot ID @var{id}.

@item delvm @var{tag}|@var{id}
Delete the snapshot identified by @var{tag} or @var{id}.

@item stop
Stop emulation.

@item c or cont
Resume emulation.

@item gdbserver [@var{port}]
Start gdbserver session (default @var{port}=1234)

@item x/fmt @var{addr}
Virtual memory dump starting at @var{addr}.

@item xp /@var{fmt} @var{addr}
Physical memory dump starting at @var{addr}.

@var{fmt} is a format which tells the command how to format the
data. Its syntax is: @option{/@{count@}@{format@}@{size@}}

@table @var
@item count
is the number of items to be dumped.

@item format
can be x (hex), d (signed decimal), u (unsigned decimal), o (octal),
c (char) or i (asm instruction).

@item size
can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits). On x86,
@code{h} or @code{w} can be specified with the @code{i} format to
respectively select 16 or 32 bit code instruction size.

@end table

Examples:
@itemize
@item
Dump 10 instructions at the current instruction pointer:
@example
(qemu) x/10i $eip
0x90107063:  ret
0x90107064:  sti
0x90107065:  lea    0x0(%esi,1),%esi
0x90107069:  lea    0x0(%edi,1),%edi
0x90107070:  ret
0x90107071:  jmp    0x90107080
0x90107073:  nop
0x90107074:  nop
0x90107075:  nop
0x90107076:  nop
@end example

@item
Dump 80 16 bit values at the start of the video memory.
@smallexample
(qemu) xp/80hx 0xb8000
0x000b8000: 0x0b50 0x0b6c 0x0b65 0x0b78 0x0b38 0x0b36 0x0b2f 0x0b42
0x000b8010: 0x0b6f 0x0b63 0x0b68 0x0b73 0x0b20 0x0b56 0x0b47 0x0b41
0x000b8020: 0x0b42 0x0b69 0x0b6f 0x0b73 0x0b20 0x0b63 0x0b75 0x0b72
0x000b8030: 0x0b72 0x0b65 0x0b6e 0x0b74 0x0b2d 0x0b63 0x0b76 0x0b73
0x000b8040: 0x0b20 0x0b30 0x0b35 0x0b20 0x0b4e 0x0b6f 0x0b76 0x0b20
0x000b8050: 0x0b32 0x0b30 0x0b30 0x0b33 0x0720 0x0720 0x0720 0x0720
0x000b8060: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8070: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8080: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8090: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
@end smallexample
@end itemize

@item p or print/@var{fmt} @var{expr}

Print expression value. Only the @var{format} part of @var{fmt} is
used.

@item sendkey @var{keys}

Send @var{keys} to the emulator. @var{keys} could be the name of the
key or @code{#} followed by the raw value in either decimal or hexadecimal
format. Use @code{-} to press several keys simultaneously. Example:
@example
sendkey ctrl-alt-f1
@end example

This command is useful to send keys that your graphical user interface
intercepts at low level, such as @code{ctrl-alt-f1} in X Window.

@item system_reset

Reset the system.

@item system_powerdown

Power down the system (if supported).

@item sum @var{addr} @var{size}

Compute the checksum of a memory region.

@item usb_add @var{devname}

Add the USB device @var{devname}.  For details of available devices see
@ref{usb_devices}

@item usb_del @var{devname}

Remove the USB device @var{devname} from the QEMU virtual USB
hub. @var{devname} has the syntax @code{bus.addr}. Use the monitor
command @code{info usb} to see the devices you can remove.

@item mouse_move @var{dx} @var{dy} [@var{dz}]
Move the active mouse to the specified coordinates @var{dx} @var{dy}
with optional scroll axis @var{dz}.

@item mouse_button @var{val}
Change the active mouse button state @var{val} (1=L, 2=M, 4=R).

@item mouse_set @var{index}
Set which mouse device receives events at given @var{index}, index
can be obtained with
@example
info mice
@end example

@item wavcapture @var{filename} [@var{frequency} [@var{bits} [@var{channels}]]]
Capture audio into @var{filename}. Using sample rate @var{frequency}
bits per sample @var{bits} and number of channels @var{channels}.

Defaults:
@itemize @minus
@item Sample rate = 44100 Hz - CD quality
@item Bits = 16
@item Number of channels = 2 - Stereo
@end itemize

@item stopcapture @var{index}
Stop capture with a given @var{index}, index can be obtained with
@example
info capture
@end example

@item memsave @var{addr} @var{size} @var{file}
save to disk virtual memory dump starting at @var{addr} of size @var{size}.

@item pmemsave @var{addr} @var{size} @var{file}
save to disk physical memory dump starting at @var{addr} of size @var{size}.

@item boot_set @var{bootdevicelist}

Define new values for the boot device list. Those values will override
the values specified on the command line through the @code{-boot} option.

The values that can be specified here depend on the machine type, but are
the same that can be specified in the @code{-boot} command line option.

@item nmi @var{cpu}
Inject an NMI on the given CPU.

@item migrate [-d] @var{uri}
Migrate to @var{uri} (using -d to not wait for completion).

@item migrate_cancel
Cancel the current VM migration.

@item migrate_set_speed @var{value}
Set maximum speed to @var{value} (in bytes) for migrations.

@item balloon @var{value}
Request VM to change its memory allocation to @var{value} (in MB).

@item set_link @var{name} [up|down]
Set link @var{name} up or down.

@end table

@subsection Integer expressions

The monitor understands integers expressions for every integer
argument. You can use register names to get the value of specifics
CPU registers by prefixing them with @emph{$}.

@node disk_images
@section Disk Images

Since version 0.6.1, QEMU supports many disk image formats, including
growable disk images (their size increase as non empty sectors are
written), compressed and encrypted disk images. Version 0.8.3 added
the new qcow2 disk image format which is essential to support VM
snapshots.

@menu
* disk_images_quickstart::    Quick start for disk image creation
* disk_images_snapshot_mode:: Snapshot mode
* vm_snapshots::              VM snapshots
* qemu_img_invocation::       qemu-img Invocation
* qemu_nbd_invocation::       qemu-nbd Invocation
* host_drives::               Using host drives
* disk_images_fat_images::    Virtual FAT disk images
* disk_images_nbd::           NBD access
@end menu

@node disk_images_quickstart
@subsection Quick start for disk image creation

You can create a disk image with the command:
@example
qemu-img create myimage.img mysize
@end example
where @var{myimage.img} is the disk image filename and @var{mysize} is its
size in kilobytes. You can add an @code{M} suffix to give the size in
megabytes and a @code{G} suffix for gigabytes.

See @ref{qemu_img_invocation} for more information.

@node disk_images_snapshot_mode
@subsection Snapshot mode

If you use the option @option{-snapshot}, all disk images are
considered as read only. When sectors in written, they are written in
a temporary file created in @file{/tmp}. You can however force the
write back to the raw disk images by using the @code{commit} monitor
command (or @key{C-a s} in the serial console).

@node vm_snapshots
@subsection VM snapshots

VM snapshots are snapshots of the complete virtual machine including
CPU state, RAM, device state and the content of all the writable
disks. In order to use VM snapshots, you must have at least one non
removable and writable block device using the @code{qcow2} disk image
format. Normally this device is the first virtual hard drive.

Use the monitor command @code{savevm} to create a new VM snapshot or
replace an existing one. A human readable name can be assigned to each
snapshot in addition to its numerical ID.

Use @code{loadvm} to restore a VM snapshot and @code{delvm} to remove
a VM snapshot. @code{info snapshots} lists the available snapshots
with their associated information:

@example
(qemu) info snapshots
Snapshot devices: hda
Snapshot list (from hda):
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         start                   41M 2006-08-06 12:38:02   00:00:14.954
2                                 40M 2006-08-06 12:43:29   00:00:18.633
3         msys                    40M 2006-08-06 12:44:04   00:00:23.514
@end example

A VM snapshot is made of a VM state info (its size is shown in
@code{info snapshots}) and a snapshot of every writable disk image.
The VM state info is stored in the first @code{qcow2} non removable
and writable block device. The disk image snapshots are stored in
every disk image. The size of a snapshot in a disk image is difficult
to evaluate and is not shown by @code{info snapshots} because the
associated disk sectors are shared among all the snapshots to save
disk space (otherwise each snapshot would need a full copy of all the
disk images).

When using the (unrelated) @code{-snapshot} option
(@ref{disk_images_snapshot_mode}), you can always make VM snapshots,
but they are deleted as soon as you exit QEMU.

VM snapshots currently have the following known limitations:
@itemize
@item
They cannot cope with removable devices if they are removed or
inserted after a snapshot is done.
@item
A few device drivers still have incomplete snapshot support so their
state is not saved or restored properly (in particular USB).
@end itemize

@node qemu_img_invocation
@subsection @code{qemu-img} Invocation

@include qemu-img.texi

@node qemu_nbd_invocation
@subsection @code{qemu-nbd} Invocation

@include qemu-nbd.texi

@node host_drives
@subsection Using host drives

In addition to disk image files, QEMU can directly access host
devices. We describe here the usage for QEMU version >= 0.8.3.

@subsubsection Linux

On Linux, you can directly use the host device filename instead of a
disk image filename provided you have enough privileges to access
it. For example, use @file{/dev/cdrom} to access to the CDROM or
@file{/dev/fd0} for the floppy.

@table @code
@item CD
You can specify a CDROM device even if no CDROM is loaded. QEMU has
specific code to detect CDROM insertion or removal. CDROM ejection by
the guest OS is supported. Currently only data CDs are supported.
@item Floppy
You can specify a floppy device even if no floppy is loaded. Floppy
removal is currently not detected accurately (if you change floppy
without doing floppy access while the floppy is not loaded, the guest
OS will think that the same floppy is loaded).
@item Hard disks
Hard disks can be used. Normally you must specify the whole disk
(@file{/dev/hdb} instead of @file{/dev/hdb1}) so that the guest OS can
see it as a partitioned disk. WARNING: unless you know what you do, it
is better to only make READ-ONLY accesses to the hard disk otherwise
you may corrupt your host data (use the @option{-snapshot} command
line option or modify the device permissions accordingly).
@end table

@subsubsection Windows

@table @code
@item CD
The preferred syntax is the drive letter (e.g. @file{d:}). The
alternate syntax @file{\\.\d:} is supported. @file{/dev/cdrom} is
supported as an alias to the first CDROM drive.

Currently there is no specific code to handle removable media, so it
is better to use the @code{change} or @code{eject} monitor commands to
change or eject media.
@item Hard disks
Hard disks can be used with the syntax: @file{\\.\PhysicalDrive@var{N}}
where @var{N} is the drive number (0 is the first hard disk).

WARNING: unless you know what you do, it is better to only make
READ-ONLY accesses to the hard disk otherwise you may corrupt your
host data (use the @option{-snapshot} command line so that the
modifications are written in a temporary file).
@end table


@subsubsection Mac OS X

@file{/dev/cdrom} is an alias to the first CDROM.

Currently there is no specific code to handle removable media, so it
is better to use the @code{change} or @code{eject} monitor commands to
change or eject media.

@node disk_images_fat_images
@subsection Virtual FAT disk images

QEMU can automatically create a virtual FAT disk image from a
directory tree. In order to use it, just type:

@example
qemu linux.img -hdb fat:/my_directory
@end example

Then you access access to all the files in the @file{/my_directory}
directory without having to copy them in a disk image or to export
them via SAMBA or NFS. The default access is @emph{read-only}.

Floppies can be emulated with the @code{:floppy:} option:

@example
qemu linux.img -fda fat:floppy:/my_directory
@end example

A read/write support is available for testing (beta stage) with the
@code{:rw:} option:

@example
qemu linux.img -fda fat:floppy:rw:/my_directory
@end example

What you should @emph{never} do:
@itemize
@item use non-ASCII filenames ;
@item use "-snapshot" together with ":rw:" ;
@item expect it to work when loadvm'ing ;
@item write to the FAT directory on the host system while accessing it with the guest system.
@end itemize

@node disk_images_nbd
@subsection NBD access

QEMU can access directly to block device exported using the Network Block Device
protocol.

@example
qemu linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
@end example

If the NBD server is located on the same host, you can use an unix socket instead
of an inet socket:

@example
qemu linux.img -hdb nbd:unix:/tmp/my_socket
@end example

In this case, the block device must be exported using qemu-nbd:

@example
qemu-nbd --socket=/tmp/my_socket my_disk.qcow2
@end example

The use of qemu-nbd allows to share a disk between several guests:
@example
qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2
@end example

and then you can use it with two guests:
@example
qemu linux1.img -hdb nbd:unix:/tmp/my_socket
qemu linux2.img -hdb nbd:unix:/tmp/my_socket
@end example

@node pcsys_network
@section Network emulation

QEMU can simulate several network cards (PCI or ISA cards on the PC
target) and can connect them to an arbitrary number of Virtual Local
Area Networks (VLANs). Host TAP devices can be connected to any QEMU
VLAN. VLAN can be connected between separate instances of QEMU to
simulate large networks. For simpler usage, a non privileged user mode
network stack can replace the TAP device to have a basic network
connection.

@subsection VLANs

QEMU simulates several VLANs. A VLAN can be symbolised as a virtual
connection between several network devices. These devices can be for
example QEMU virtual Ethernet cards or virtual Host ethernet devices
(TAP devices).

@subsection Using TAP network interfaces

This is the standard way to connect QEMU to a real network. QEMU adds
a virtual network device on your host (called @code{tapN}), and you
can then configure it as if it was a real ethernet card.

@subsubsection Linux host

As an example, you can download the @file{linux-test-xxx.tar.gz}
archive and copy the script @file{qemu-ifup} in @file{/etc} and
configure properly @code{sudo} so that the command @code{ifconfig}
contained in @file{qemu-ifup} can be executed as root. You must verify
that your host kernel supports the TAP network interfaces: the
device @file{/dev/net/tun} must be present.

See @ref{sec_invocation} to have examples of command lines using the
TAP network interfaces.

@subsubsection Windows host

There is a virtual ethernet driver for Windows 2000/XP systems, called
TAP-Win32. But it is not included in standard QEMU for Windows,
so you will need to get it separately. It is part of OpenVPN package,
so download OpenVPN from : @url{http://openvpn.net/}.

@subsection Using the user mode network stack

By using the option @option{-net user} (default configuration if no
@option{-net} option is specified), QEMU uses a completely user mode
network stack (you don't need root privilege to use the virtual
network). The virtual network configuration is the following:

@example

         QEMU VLAN      <------>  Firewall/DHCP server <-----> Internet
                           |          (10.0.2.2)
                           |
                           ---->  DNS server (10.0.2.3)
                           |
                           ---->  SMB server (10.0.2.4)
@end example

The QEMU VM behaves as if it was behind a firewall which blocks all
incoming connections. You can use a DHCP client to automatically
configure the network in the QEMU VM. The DHCP server assign addresses
to the hosts starting from 10.0.2.15.

In order to check that the user mode network is working, you can ping
the address 10.0.2.2 and verify that you got an address in the range
10.0.2.x from the QEMU virtual DHCP server.

Note that @code{ping} is not supported reliably to the internet as it
would require root privileges. It means you can only ping the local
router (10.0.2.2).

When using the built-in TFTP server, the router is also the TFTP
server.

When using the @option{-redir} option, TCP or UDP connections can be
redirected from the host to the guest. It allows for example to
redirect X11, telnet or SSH connections.

@subsection Connecting VLANs between QEMU instances

Using the @option{-net socket} option, it is possible to make VLANs
that span several QEMU instances. See @ref{sec_invocation} to have a
basic example.

@node direct_linux_boot
@section Direct Linux Boot

This section explains how to launch a Linux kernel inside QEMU without
having to make a full bootable image. It is very useful for fast Linux
kernel testing.

The syntax is:
@example
qemu -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"
@end example

Use @option{-kernel} to provide the Linux kernel image and
@option{-append} to give the kernel command line arguments. The
@option{-initrd} option can be used to provide an INITRD image.

When using the direct Linux boot, a disk image for the first hard disk
@file{hda} is required because its boot sector is used to launch the
Linux kernel.

If you do not need graphical output, you can disable it and redirect
the virtual serial port and the QEMU monitor to the console with the
@option{-nographic} option. The typical command line is:
@example
qemu -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
     -append "root=/dev/hda console=ttyS0" -nographic
@end example

Use @key{Ctrl-a c} to switch between the serial console and the
monitor (@pxref{pcsys_keys}).

@node pcsys_usb
@section USB emulation

QEMU emulates a PCI UHCI USB controller. You can virtually plug
virtual USB devices or real host USB devices (experimental, works only
on Linux hosts).  Qemu will automatically create and connect virtual USB hubs
as necessary to connect multiple USB devices.

@menu
* usb_devices::
* host_usb_devices::
@end menu
@node usb_devices
@subsection Connecting USB devices

USB devices can be connected with the @option{-usbdevice} commandline option
or the @code{usb_add} monitor command.  Available devices are:

@table @code
@item mouse
Virtual Mouse.  This will override the PS/2 mouse emulation when activated.
@item tablet
Pointer device that uses absolute coordinates (like a touchscreen).
This means qemu is able to report the mouse position without having
to grab the mouse.  Also overrides the PS/2 mouse emulation when activated.
@item disk:@var{file}
Mass storage device based on @var{file} (@pxref{disk_images})
@item host:@var{bus.addr}
Pass through the host device identified by @var{bus.addr}
(Linux only)
@item host:@var{vendor_id:product_id}
Pass through the host device identified by @var{vendor_id:product_id}
(Linux only)
@item wacom-tablet
Virtual Wacom PenPartner tablet.  This device is similar to the @code{tablet}
above but it can be used with the tslib library because in addition to touch
coordinates it reports touch pressure.
@item keyboard
Standard USB keyboard.  Will override the PS/2 keyboard (if present).
@item serial:[vendorid=@var{vendor_id}][,product_id=@var{product_id}]:@var{dev}
Serial converter. This emulates an FTDI FT232BM chip connected to host character
device @var{dev}. The available character devices are the same as for the
@code{-serial} option. The @code{vendorid} and @code{productid} options can be
used to override the default 0403:6001. For instance, 
@example
usb_add serial:productid=FA00:tcp:192.168.0.2:4444
@end example
will connect to tcp port 4444 of ip 192.168.0.2, and plug that to the virtual
serial converter, faking a Matrix Orbital LCD Display (USB ID 0403:FA00).
@item braille
Braille device.  This will use BrlAPI to display the braille output on a real
or fake device.
@item net:@var{options}
Network adapter that supports CDC ethernet and RNDIS protocols.  @var{options}
specifies NIC options as with @code{-net nic,}@var{options} (see description).
For instance, user-mode networking can be used with
@example
qemu [...OPTIONS...] -net user,vlan=0 -usbdevice net:vlan=0
@end example
Currently this cannot be used in machines that support PCI NICs.
@item bt[:@var{hci-type}]
Bluetooth dongle whose type is specified in the same format as with
the @option{-bt hci} option, @pxref{bt-hcis,,allowed HCI types}.  If
no type is given, the HCI logic corresponds to @code{-bt hci,vlan=0}.
This USB device implements the USB Transport Layer of HCI.  Example
usage:
@example
qemu [...OPTIONS...] -usbdevice bt:hci,vlan=3 -bt device:keyboard,vlan=3
@end example
@end table

@node host_usb_devices
@subsection Using host USB devices on a Linux host

WARNING: this is an experimental feature. QEMU will slow down when
using it. USB devices requiring real time streaming (i.e. USB Video
Cameras) are not supported yet.

@enumerate
@item If you use an early Linux 2.4 kernel, verify that no Linux driver
is actually using the USB device. A simple way to do that is simply to
disable the corresponding kernel module by renaming it from @file{mydriver.o}
to @file{mydriver.o.disabled}.

@item Verify that @file{/proc/bus/usb} is working (most Linux distributions should enable it by default). You should see something like that:
@example
ls /proc/bus/usb
001  devices  drivers
@end example

@item Since only root can access to the USB devices directly, you can either launch QEMU as root or change the permissions of the USB devices you want to use. For testing, the following suffices:
@example
chown -R myuid /proc/bus/usb
@end example

@item Launch QEMU and do in the monitor:
@example
info usbhost
  Device 1.2, speed 480 Mb/s
    Class 00: USB device 1234:5678, USB DISK
@end example
You should see the list of the devices you can use (Never try to use
hubs, it won't work).

@item Add the device in QEMU by using:
@example
usb_add host:1234:5678
@end example

Normally the guest OS should report that a new USB device is
plugged. You can use the option @option{-usbdevice} to do the same.

@item Now you can try to use the host USB device in QEMU.

@end enumerate

When relaunching QEMU, you may have to unplug and plug again the USB
device to make it work again (this is a bug).

@node vnc_security
@section VNC security

The VNC server capability provides access to the graphical console
of the guest VM across the network. This has a number of security
considerations depending on the deployment scenarios.

@menu
* vnc_sec_none::
* vnc_sec_password::
* vnc_sec_certificate::
* vnc_sec_certificate_verify::
* vnc_sec_certificate_pw::
* vnc_sec_sasl::
* vnc_sec_certificate_sasl::
* vnc_generate_cert::
* vnc_setup_sasl::
@end menu
@node vnc_sec_none
@subsection Without passwords

The simplest VNC server setup does not include any form of authentication.
For this setup it is recommended to restrict it to listen on a UNIX domain
socket only. For example

@example
qemu [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc
@end example

This ensures that only users on local box with read/write access to that
path can access the VNC server. To securely access the VNC server from a
remote machine, a combination of netcat+ssh can be used to provide a secure
tunnel.

@node vnc_sec_password
@subsection With passwords

The VNC protocol has limited support for password based authentication. Since
the protocol limits passwords to 8 characters it should not be considered
to provide high security. The password can be fairly easily brute-forced by
a client making repeat connections. For this reason, a VNC server using password
authentication should be restricted to only listen on the loopback interface
or UNIX domain sockets. Password authentication is requested with the @code{password}
option, and then once QEMU is running the password is set with the monitor. Until
the monitor is used to set the password all clients will be rejected.

@example
qemu [...OPTIONS...] -vnc :1,password -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)
@end example

@node vnc_sec_certificate
@subsection With x509 certificates

The QEMU VNC server also implements the VeNCrypt extension allowing use of
TLS for encryption of the session, and x509 certificates for authentication.
The use of x509 certificates is strongly recommended, because TLS on its
own is susceptible to man-in-the-middle attacks. Basic x509 certificate
support provides a secure session, but no authentication. This allows any
client to connect, and provides an encrypted session.

@example
qemu [...OPTIONS...] -vnc :1,tls,x509=/etc/pki/qemu -monitor stdio
@end example

In the above example @code{/etc/pki/qemu} should contain at least three files,
@code{ca-cert.pem}, @code{server-cert.pem} and @code{server-key.pem}. Unprivileged
users will want to use a private directory, for example @code{$HOME/.pki/qemu}.
NB the @code{server-key.pem} file should be protected with file mode 0600 to
only be readable by the user owning it.

@node vnc_sec_certificate_verify
@subsection With x509 certificates and client verification

Certificates can also provide a means to authenticate the client connecting.
The server will request that the client provide a certificate, which it will
then validate against the CA certificate. This is a good choice if deploying
in an environment with a private internal certificate authority.

@example
qemu [...OPTIONS...] -vnc :1,tls,x509verify=/etc/pki/qemu -monitor stdio
@end example


@node vnc_sec_certificate_pw
@subsection With x509 certificates, client verification and passwords

Finally, the previous method can be combined with VNC password authentication
to provide two layers of authentication for clients.

@example
qemu [...OPTIONS...] -vnc :1,password,tls,x509verify=/etc/pki/qemu -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)
@end example


@node vnc_sec_sasl
@subsection With SASL authentication

The SASL authentication method is a VNC extension, that provides an
easily extendable, pluggable authentication method. This allows for
integration with a wide range of authentication mechanisms, such as
PAM, GSSAPI/Kerberos, LDAP, SQL databases, one-time keys and more.
The strength of the authentication depends on the exact mechanism
configured. If the chosen mechanism also provides a SSF layer, then
it will encrypt the datastream as well.

Refer to the later docs on how to choose the exact SASL mechanism
used for authentication, but assuming use of one supporting SSF,
then QEMU can be launched with:

@example
qemu [...OPTIONS...] -vnc :1,sasl -monitor stdio
@end example

@node vnc_sec_certificate_sasl
@subsection With x509 certificates and SASL authentication

If the desired SASL authentication mechanism does not supported
SSF layers, then it is strongly advised to run it in combination
with TLS and x509 certificates. This provides securely encrypted
data stream, avoiding risk of compromising of the security
credentials. This can be enabled, by combining the 'sasl' option
with the aforementioned TLS + x509 options:

@example
qemu [...OPTIONS...] -vnc :1,tls,x509,sasl -monitor stdio
@end example


@node vnc_generate_cert
@subsection Generating certificates for VNC

The GNU TLS packages provides a command called @code{certtool} which can
be used to generate certificates and keys in PEM format. At a minimum it
is neccessary to setup a certificate authority, and issue certificates to
each server. If using certificates for authentication, then each client
will also need to be issued a certificate. The recommendation is for the
server to keep its certificates in either @code{/etc/pki/qemu} or for
unprivileged users in @code{$HOME/.pki/qemu}.

@menu
* vnc_generate_ca::
* vnc_generate_server::
* vnc_generate_client::
@end menu
@node vnc_generate_ca
@subsubsection Setup the Certificate Authority

This step only needs to be performed once per organization / organizational
unit. First the CA needs a private key. This key must be kept VERY secret
and secure. If this key is compromised the entire trust chain of the certificates
issued with it is lost.

@example
# certtool --generate-privkey > ca-key.pem
@end example

A CA needs to have a public certificate. For simplicity it can be a self-signed
certificate, or one issue by a commercial certificate issuing authority. To
generate a self-signed certificate requires one core piece of information, the
name of the organization.

@example
# cat > ca.info <<EOF
cn = Name of your organization
ca
cert_signing_key
EOF
# certtool --generate-self-signed \
           --load-privkey ca-key.pem
           --template ca.info \
           --outfile ca-cert.pem
@end example

The @code{ca-cert.pem} file should be copied to all servers and clients wishing to utilize
TLS support in the VNC server. The @code{ca-key.pem} must not be disclosed/copied at all.

@node vnc_generate_server
@subsubsection Issuing server certificates

Each server (or host) needs to be issued with a key and certificate. When connecting
the certificate is sent to the client which validates it against the CA certificate.
The core piece of information for a server certificate is the hostname. This should
be the fully qualified hostname that the client will connect with, since the client
will typically also verify the hostname in the certificate. On the host holding the
secure CA private key:

@example
# cat > server.info <<EOF
organization = Name  of your organization
cn = server.foo.example.com
tls_www_server
encryption_key
signing_key
EOF
# certtool --generate-privkey > server-key.pem
# certtool --generate-certificate \
           --load-ca-certificate ca-cert.pem \
           --load-ca-privkey ca-key.pem \
           --load-privkey server server-key.pem \
           --template server.info \
           --outfile server-cert.pem
@end example

The @code{server-key.pem} and @code{server-cert.pem} files should now be securely copied
to the server for which they were generated. The @code{server-key.pem} is security
sensitive and should be kept protected with file mode 0600 to prevent disclosure.

@node vnc_generate_client
@subsubsection Issuing client certificates

If the QEMU VNC server is to use the @code{x509verify} option to validate client
certificates as its authentication mechanism, each client also needs to be issued
a certificate. The client certificate contains enough metadata to uniquely identify
the client, typically organization, state, city, building, etc. On the host holding
the secure CA private key:

@example
# cat > client.info <<EOF
country = GB
state = London
locality = London
organiazation = Name of your organization
cn = client.foo.example.com
tls_www_client
encryption_key
signing_key
EOF
# certtool --generate-privkey > client-key.pem
# certtool --generate-certificate \
           --load-ca-certificate ca-cert.pem \
           --load-ca-privkey ca-key.pem \
           --load-privkey client-key.pem \
           --template client.info \
           --outfile client-cert.pem
@end example

The @code{client-key.pem} and @code{client-cert.pem} files should now be securely
copied to the client for which they were generated.


@node vnc_setup_sasl

@subsection Configuring SASL mechanisms

The following documentation assumes use of the Cyrus SASL implementation on a
Linux host, but the principals should apply to any other SASL impl. When SASL
is enabled, the mechanism configuration will be loaded from system default
SASL service config /etc/sasl2/qemu.conf. If running QEMU as an
unprivileged user, an environment variable SASL_CONF_PATH can be used
to make it search alternate locations for the service config.

The default configuration might contain

@example
mech_list: digest-md5
sasldb_path: /etc/qemu/passwd.db
@end example

This says to use the 'Digest MD5' mechanism, which is similar to the HTTP
Digest-MD5 mechanism. The list of valid usernames & passwords is maintained
in the /etc/qemu/passwd.db file, and can be updated using the saslpasswd2
command. While this mechanism is easy to configure and use, it is not
considered secure by modern standards, so only suitable for developers /
ad-hoc testing.

A more serious deployment might use Kerberos, which is done with the 'gssapi'
mechanism

@example
mech_list: gssapi
keytab: /etc/qemu/krb5.tab
@end example

For this to work the administrator of your KDC must generate a Kerberos
principal for the server, with a name of  'qemu/somehost.example.com@@EXAMPLE.COM'
replacing 'somehost.example.com' with the fully qualified host name of the
machine running QEMU, and 'EXAMPLE.COM' with the Keberos Realm.

Other configurations will be left as an exercise for the reader. It should
be noted that only Digest-MD5 and GSSAPI provides a SSF layer for data
encryption. For all other mechanisms, VNC should always be configured to
use TLS and x509 certificates to protect security credentials from snooping.

@node gdb_usage
@section GDB usage

QEMU has a primitive support to work with gdb, so that you can do
'Ctrl-C' while the virtual machine is running and inspect its state.

In order to use gdb, launch qemu with the '-s' option. It will wait for a
gdb connection:
@example
> qemu -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
       -append "root=/dev/hda"
Connected to host network interface: tun0
Waiting gdb connection on port 1234
@end example

Then launch gdb on the 'vmlinux' executable:
@example
> gdb vmlinux
@end example

In gdb, connect to QEMU:
@example
(gdb) target remote localhost:1234
@end example

Then you can use gdb normally. For example, type 'c' to launch the kernel:
@example
(gdb) c
@end example

Here are some useful tips in order to use gdb on system code:

@enumerate
@item
Use @code{info reg} to display all the CPU registers.
@item
Use @code{x/10i $eip} to display the code at the PC position.
@item
Use @code{set architecture i8086} to dump 16 bit code. Then use
@code{x/10i $cs*16+$eip} to dump the code at the PC position.
@end enumerate

Advanced debugging options:

The default single stepping behavior is step with the IRQs and timer service routines off.  It is set this way because when gdb executes a single step it expects to advance beyond the current instruction.  With the IRQs and and timer service routines on, a single step might jump into the one of the interrupt or exception vectors instead of executing the current instruction. This means you may hit the same breakpoint a number of times before executing the instruction gdb wants to have executed.  Because there are rare circumstances where you want to single step into an interrupt vector the behavior can be controlled from GDB.  There are three commands you can query and set the single step behavior:
@table @code
@item maintenance packet qqemu.sstepbits

This will display the MASK bits used to control the single stepping IE:
@example
(gdb) maintenance packet qqemu.sstepbits
sending: "qqemu.sstepbits"
received: "ENABLE=1,NOIRQ=2,NOTIMER=4"
@end example
@item maintenance packet qqemu.sstep

This will display the current value of the mask used when single stepping IE:
@example
(gdb) maintenance packet qqemu.sstep
sending: "qqemu.sstep"
received: "0x7"
@end example
@item maintenance packet Qqemu.sstep=HEX_VALUE

This will change the single step mask, so if wanted to enable IRQs on the single step, but not timers, you would use:
@example
(gdb) maintenance packet Qqemu.sstep=0x5
sending: "qemu.sstep=0x5"
received: "OK"
@end example
@end table

@node pcsys_os_specific
@section Target OS specific information

@subsection Linux

To have access to SVGA graphic modes under X11, use the @code{vesa} or
the @code{cirrus} X11 driver. For optimal performances, use 16 bit
color depth in the guest and the host OS.

When using a 2.6 guest Linux kernel, you should add the option
@code{clock=pit} on the kernel command line because the 2.6 Linux
kernels make very strict real time clock checks by default that QEMU
cannot simulate exactly.

When using a 2.6 guest Linux kernel, verify that the 4G/4G patch is
not activated because QEMU is slower with this patch. The QEMU
Accelerator Module is also much slower in this case. Earlier Fedora
Core 3 Linux kernel (< 2.6.9-1.724_FC3) were known to incorporate this
patch by default. Newer kernels don't have it.

@subsection Windows

If you have a slow host, using Windows 95 is better as it gives the
best speed. Windows 2000 is also a good choice.

@subsubsection SVGA graphic modes support

QEMU emulates a Cirrus Logic GD5446 Video
card. All Windows versions starting from Windows 95 should recognize
and use this graphic card. For optimal performances, use 16 bit color
depth in the guest and the host OS.

If you are using Windows XP as guest OS and if you want to use high
resolution modes which the Cirrus Logic BIOS does not support (i.e. >=
1280x1024x16), then you should use the VESA VBE virtual graphic card
(option @option{-std-vga}).

@subsubsection CPU usage reduction

Windows 9x does not correctly use the CPU HLT
instruction. The result is that it takes host CPU cycles even when
idle. You can install the utility from
@url{http://www.user.cityline.ru/~maxamn/amnhltm.zip} to solve this
problem. Note that no such tool is needed for NT, 2000 or XP.

@subsubsection Windows 2000 disk full problem

Windows 2000 has a bug which gives a disk full problem during its
installation. When installing it, use the @option{-win2k-hack} QEMU
option to enable a specific workaround. After Windows 2000 is
installed, you no longer need this option (this option slows down the
IDE transfers).

@subsubsection Windows 2000 shutdown

Windows 2000 cannot automatically shutdown in QEMU although Windows 98
can. It comes from the fact that Windows 2000 does not automatically
use the APM driver provided by the BIOS.

In order to correct that, do the following (thanks to Struan
Bartlett): go to the Control Panel => Add/Remove Hardware & Next =>
Add/Troubleshoot a device => Add a new device & Next => No, select the
hardware from a list & Next => NT Apm/Legacy Support & Next => Next
(again) a few times. Now the driver is installed and Windows 2000 now
correctly instructs QEMU to shutdown at the appropriate moment.

@subsubsection Share a directory between Unix and Windows

See @ref{sec_invocation} about the help of the option @option{-smb}.

@subsubsection Windows XP security problem

Some releases of Windows XP install correctly but give a security
error when booting:
@example
A problem is preventing Windows from accurately checking the
license for this computer. Error code: 0x800703e6.
@end example

The workaround is to install a service pack for XP after a boot in safe
mode. Then reboot, and the problem should go away. Since there is no
network while in safe mode, its recommended to download the full
installation of SP1 or SP2 and transfer that via an ISO or using the
vvfat block device ("-hdb fat:directory_which_holds_the_SP").

@subsection MS-DOS and FreeDOS

@subsubsection CPU usage reduction

DOS does not correctly use the CPU HLT instruction. The result is that
it takes host CPU cycles even when idle. You can install the utility
from @url{http://www.vmware.com/software/dosidle210.zip} to solve this
problem.

@node QEMU System emulator for non PC targets
@chapter QEMU System emulator for non PC targets

QEMU is a generic emulator and it emulates many non PC
machines. Most of the options are similar to the PC emulator. The
differences are mentioned in the following sections.

@menu
* QEMU PowerPC System emulator::
* Sparc32 System emulator::
* Sparc64 System emulator::
* MIPS System emulator::
* ARM System emulator::
* ColdFire System emulator::
@end menu

@node QEMU PowerPC System emulator
@section QEMU PowerPC System emulator

Use the executable @file{qemu-system-ppc} to simulate a complete PREP
or PowerMac PowerPC system.

QEMU emulates the following PowerMac peripherals:

@itemize @minus
@item
UniNorth or Grackle PCI Bridge
@item
PCI VGA compatible card with VESA Bochs Extensions
@item
2 PMAC IDE interfaces with hard disk and CD-ROM support
@item
NE2000 PCI adapters
@item
Non Volatile RAM
@item
VIA-CUDA with ADB keyboard and mouse.
@end itemize

QEMU emulates the following PREP peripherals:

@itemize @minus
@item
PCI Bridge
@item
PCI VGA compatible card with VESA Bochs Extensions
@item
2 IDE interfaces with hard disk and CD-ROM support
@item
Floppy disk
@item
NE2000 network adapters
@item
Serial port
@item
PREP Non Volatile RAM
@item
PC compatible keyboard and mouse.
@end itemize

QEMU uses the Open Hack'Ware Open Firmware Compatible BIOS available at
@url{http://perso.magic.fr/l_indien/OpenHackWare/index.htm}.

Since version 0.9.1, QEMU uses OpenBIOS @url{http://www.openbios.org/}
for the g3beige and mac99 PowerMac machines. OpenBIOS is a free (GPL
v2) portable firmware implementation. The goal is to implement a 100%
IEEE 1275-1994 (referred to as Open Firmware) compliant firmware.

@c man begin OPTIONS

The following options are specific to the PowerPC emulation:

@table @option

@item -g WxH[xDEPTH]

Set the initial VGA graphic mode. The default is 800x600x15.

@item -prom-env string

Set OpenBIOS variables in NVRAM, for example:

@example
qemu-system-ppc -prom-env 'auto-boot?=false' \
 -prom-env 'boot-device=hd:2,\yaboot' \
 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
@end example

These variables are not used by Open Hack'Ware.

@end table

@c man end


More information is available at
@url{http://perso.magic.fr/l_indien/qemu-ppc/}.

@node Sparc32 System emulator
@section Sparc32 System emulator

Use the executable @file{qemu-system-sparc} to simulate the following
Sun4m architecture machines:
@itemize @minus
@item
SPARCstation 4
@item
SPARCstation 5
@item
SPARCstation 10
@item
SPARCstation 20
@item
SPARCserver 600MP
@item
SPARCstation LX
@item
SPARCstation Voyager
@item
SPARCclassic
@item
SPARCbook
@end itemize

The emulation is somewhat complete. SMP up to 16 CPUs is supported,
but Linux limits the number of usable CPUs to 4.

It's also possible to simulate a SPARCstation 2 (sun4c architecture),
SPARCserver 1000, or SPARCcenter 2000 (sun4d architecture), but these
emulators are not usable yet.

QEMU emulates the following sun4m/sun4c/sun4d peripherals:

@itemize @minus
@item
IOMMU or IO-UNITs
@item
TCX Frame buffer
@item
Lance (Am7990) Ethernet
@item
Non Volatile RAM M48T02/M48T08
@item
Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboard
and power/reset logic
@item
ESP SCSI controller with hard disk and CD-ROM support
@item
Floppy drive (not on SS-600MP)
@item
CS4231 sound device (only on SS-5, not working yet)
@end itemize

The number of peripherals is fixed in the architecture.  Maximum
memory size depends on the machine type, for SS-5 it is 256MB and for
others 2047MB.

Since version 0.8.2, QEMU uses OpenBIOS
@url{http://www.openbios.org/}. OpenBIOS is a free (GPL v2) portable
firmware implementation. The goal is to implement a 100% IEEE
1275-1994 (referred to as Open Firmware) compliant firmware.

A sample Linux 2.6 series kernel and ram disk image are available on
the QEMU web site. There are still issues with NetBSD and OpenBSD, but
some kernel versions work. Please note that currently Solaris kernels
don't work probably due to interface issues between OpenBIOS and
Solaris.

@c man begin OPTIONS

The following options are specific to the Sparc32 emulation:

@table @option

@item -g WxHx[xDEPTH]

Set the initial TCX graphic mode. The default is 1024x768x8, currently
the only other possible mode is 1024x768x24.

@item -prom-env string

Set OpenBIOS variables in NVRAM, for example:

@example
qemu-system-sparc -prom-env 'auto-boot?=false' \
 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
@end example

@item -M [SS-4|SS-5|SS-10|SS-20|SS-600MP|LX|Voyager|SPARCClassic|SPARCbook|SS-2|SS-1000|SS-2000]

Set the emulated machine type. Default is SS-5.

@end table

@c man end

@node Sparc64 System emulator
@section Sparc64 System emulator

Use the executable @file{qemu-system-sparc64} to simulate a Sun4u
(UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic
Niagara (T1) machine. The emulator is not usable for anything yet, but
it can launch some kernels.

QEMU emulates the following peripherals:

@itemize @minus
@item
UltraSparc IIi APB PCI Bridge
@item
PCI VGA compatible card with VESA Bochs Extensions
@item
PS/2 mouse and keyboard
@item
Non Volatile RAM M48T59
@item
PC-compatible serial ports
@item
2 PCI IDE interfaces with hard disk and CD-ROM support
@item
Floppy disk
@end itemize

@c man begin OPTIONS

The following options are specific to the Sparc64 emulation:

@table @option

@item -prom-env string

Set OpenBIOS variables in NVRAM, for example:

@example
qemu-system-sparc64 -prom-env 'auto-boot?=false'
@end example

@item -M [sun4u|sun4v|Niagara]

Set the emulated machine type. The default is sun4u.

@end table

@c man end

@node MIPS System emulator
@section MIPS System emulator

Four executables cover simulation of 32 and 64-bit MIPS systems in
both endian options, @file{qemu-system-mips}, @file{qemu-system-mipsel}
@file{qemu-system-mips64} and @file{qemu-system-mips64el}.
Five different machine types are emulated:

@itemize @minus
@item
A generic ISA PC-like machine "mips"
@item
The MIPS Malta prototype board "malta"
@item
An ACER Pica "pica61". This machine needs the 64-bit emulator.
@item
MIPS emulator pseudo board "mipssim"
@item
A MIPS Magnum R4000 machine "magnum". This machine needs the 64-bit emulator.
@end itemize

The generic emulation is supported by Debian 'Etch' and is able to
install Debian into a virtual disk image. The following devices are
emulated:

@itemize @minus
@item
A range of MIPS CPUs, default is the 24Kf
@item
PC style serial port
@item
PC style IDE disk
@item
NE2000 network card
@end itemize

The Malta emulation supports the following devices:

@itemize @minus
@item
Core board with MIPS 24Kf CPU and Galileo system controller
@item
PIIX4 PCI/USB/SMbus controller
@item
The Multi-I/O chip's serial device
@item
PCnet32 PCI network card
@item
Malta FPGA serial device
@item
Cirrus (default) or any other PCI VGA graphics card
@end itemize

The ACER Pica emulation supports:

@itemize @minus
@item
MIPS R4000 CPU
@item
PC-style IRQ and DMA controllers
@item
PC Keyboard
@item
IDE controller
@end itemize

The mipssim pseudo board emulation provides an environment similiar
to what the proprietary MIPS emulator uses for running Linux.
It supports:

@itemize @minus
@item
A range of MIPS CPUs, default is the 24Kf
@item
PC style serial port
@item
MIPSnet network emulation
@end itemize

The MIPS Magnum R4000 emulation supports:

@itemize @minus
@item
MIPS R4000 CPU
@item
PC-style IRQ controller
@item
PC Keyboard
@item
SCSI controller
@item
G364 framebuffer
@end itemize


@node ARM System emulator
@section ARM System emulator

Use the executable @file{qemu-system-arm} to simulate a ARM
machine. The ARM Integrator/CP board is emulated with the following
devices:

@itemize @minus
@item
ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
@item
Two PL011 UARTs
@item
SMC 91c111 Ethernet adapter
@item
PL110 LCD controller
@item
PL050 KMI with PS/2 keyboard and mouse.
@item
PL181 MultiMedia Card Interface with SD card.
@end itemize

The ARM Versatile baseboard is emulated with the following devices:

@itemize @minus
@item
ARM926E, ARM1136 or Cortex-A8 CPU
@item
PL190 Vectored Interrupt Controller
@item
Four PL011 UARTs
@item
SMC 91c111 Ethernet adapter
@item
PL110 LCD controller
@item
PL050 KMI with PS/2 keyboard and mouse.
@item
PCI host bridge.  Note the emulated PCI bridge only provides access to
PCI memory space.  It does not provide access to PCI IO space.
This means some devices (eg. ne2k_pci NIC) are not usable, and others
(eg. rtl8139 NIC) are only usable when the guest drivers use the memory
mapped control registers.
@item
PCI OHCI USB controller.
@item
LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices.
@item
PL181 MultiMedia Card Interface with SD card.
@end itemize

The ARM RealView Emulation baseboard is emulated with the following devices:

@itemize @minus
@item
ARM926E, ARM1136, ARM11MPCORE(x4) or Cortex-A8 CPU
@item
ARM AMBA Generic/Distributed Interrupt Controller
@item
Four PL011 UARTs
@item
SMC 91c111 Ethernet adapter
@item
PL110 LCD controller
@item
PL050 KMI with PS/2 keyboard and mouse
@item
PCI host bridge
@item
PCI OHCI USB controller
@item
LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices
@item
PL181 MultiMedia Card Interface with SD card.
@end itemize

The XScale-based clamshell PDA models ("Spitz", "Akita", "Borzoi"
and "Terrier") emulation includes the following peripherals:

@itemize @minus
@item
Intel PXA270 System-on-chip (ARM V5TE core)
@item
NAND Flash memory
@item
IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in "Akita"
@item
On-chip OHCI USB controller
@item
On-chip LCD controller
@item
On-chip Real Time Clock
@item
TI ADS7846 touchscreen controller on SSP bus
@item
Maxim MAX1111 analog-digital converter on I@math{^2}C bus
@item
GPIO-connected keyboard controller and LEDs
@item
Secure Digital card connected to PXA MMC/SD host
@item
Three on-chip UARTs
@item
WM8750 audio CODEC on I@math{^2}C and I@math{^2}S busses
@end itemize

The Palm Tungsten|E PDA (codename "Cheetah") emulation includes the
following elements:

@itemize @minus
@item
Texas Instruments OMAP310 System-on-chip (ARM 925T core)
@item
ROM and RAM memories (ROM firmware image can be loaded with -option-rom)
@item
On-chip LCD controller
@item
On-chip Real Time Clock
@item
TI TSC2102i touchscreen controller / analog-digital converter / Audio
CODEC, connected through MicroWire and I@math{^2}S busses
@item
GPIO-connected matrix keypad
@item
Secure Digital card connected to OMAP MMC/SD host
@item
Three on-chip UARTs
@end itemize

Nokia N800 and N810 internet tablets (known also as RX-34 and RX-44 / 48)
emulation supports the following elements:

@itemize @minus
@item
Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)
@item
RAM and non-volatile OneNAND Flash memories
@item
Display connected to EPSON remote framebuffer chip and OMAP on-chip
display controller and a LS041y3 MIPI DBI-C controller
@item
TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen controllers
driven through SPI bus
@item
National Semiconductor LM8323-controlled qwerty keyboard driven
through I@math{^2}C bus
@item
Secure Digital card connected to OMAP MMC/SD host
@item
Three OMAP on-chip UARTs and on-chip STI debugging console
@item
A Bluetooth(R) transciever and HCI connected to an UART
@item
Mentor Graphics "Inventra" dual-role USB controller embedded in a TI
TUSB6010 chip - only USB host mode is supported
@item
TI TMP105 temperature sensor driven through I@math{^2}C bus
@item
TI TWL92230C power management companion with an RTC on I@math{^2}C bus
@item
Nokia RETU and TAHVO multi-purpose chips with an RTC, connected
through CBUS
@end itemize

The Luminary Micro Stellaris LM3S811EVB emulation includes the following
devices:

@itemize @minus
@item
Cortex-M3 CPU core.
@item
64k Flash and 8k SRAM.
@item
Timers, UARTs, ADC and I@math{^2}C interface.
@item
OSRAM Pictiva 96x16 OLED with SSD0303 controller on I@math{^2}C bus.
@end itemize

The Luminary Micro Stellaris LM3S6965EVB emulation includes the following
devices:

@itemize @minus
@item
Cortex-M3 CPU core.
@item
256k Flash and 64k SRAM.
@item
Timers, UARTs, ADC, I@math{^2}C and SSI interfaces.
@item
OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via SSI.
@end itemize

The Freecom MusicPal internet radio emulation includes the following
elements:

@itemize @minus
@item
Marvell MV88W8618 ARM core.
@item
32 MB RAM, 256 KB SRAM, 8 MB flash.
@item
Up to 2 16550 UARTs
@item
MV88W8xx8 Ethernet controller
@item
MV88W8618 audio controller, WM8750 CODEC and mixer
@item