qemu-doc.texi 90.1 KB
Newer Older
bellard's avatar
bellard committed
1
\input texinfo @c -*- texinfo -*-
2 3
@c %**start of header
@setfilename qemu-doc.info
4 5 6 7

@documentlanguage en
@documentencoding UTF-8

bellard's avatar
bellard committed
8
@settitle QEMU Emulator User Documentation
9 10 11
@exampleindent 0
@paragraphindent 0
@c %**end of header
bellard's avatar
bellard committed
12

13 14 15 16 17 18
@ifinfo
@direntry
* QEMU: (qemu-doc).    The QEMU Emulator User Documentation.
@end direntry
@end ifinfo

bellard's avatar
bellard committed
19
@iftex
bellard's avatar
bellard committed
20 21
@titlepage
@sp 7
bellard's avatar
bellard committed
22
@center @titlefont{QEMU Emulator}
23 24
@sp 1
@center @titlefont{User Documentation}
bellard's avatar
bellard committed
25 26
@sp 3
@end titlepage
bellard's avatar
bellard committed
27
@end iftex
bellard's avatar
bellard committed
28

29 30 31 32 33 34 35 36 37
@ifnottex
@node Top
@top

@menu
* Introduction::
* Installation::
* QEMU PC System emulator::
* QEMU System emulator for non PC targets::
38
* QEMU User space emulator::
39
* compilation:: Compilation from the sources
40
* License::
41 42 43 44 45 46 47
* Index::
@end menu
@end ifnottex

@contents

@node Introduction
bellard's avatar
bellard committed
48 49
@chapter Introduction

50 51 52 53 54
@menu
* intro_features:: Features
@end menu

@node intro_features
bellard's avatar
bellard committed
55
@section Features
bellard's avatar
bellard committed
56

bellard's avatar
bellard committed
57 58
QEMU is a FAST! processor emulator using dynamic translation to
achieve good emulation speed.
bellard's avatar
bellard committed
59 60

QEMU has two operating modes:
bellard's avatar
bellard committed
61

Stefan Weil's avatar
Stefan Weil committed
62
@itemize
63
@cindex operating modes
bellard's avatar
bellard committed
64

65
@item
66
@cindex system emulation
bellard's avatar
bellard committed
67
Full system emulation. In this mode, QEMU emulates a full system (for
bellard's avatar
bellard committed
68 69 70
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.
bellard's avatar
bellard committed
71

72
@item
73
@cindex user mode emulation
74 75
User mode emulation. In this mode, QEMU can launch
processes compiled for one CPU on another CPU. It can be used to
bellard's avatar
bellard committed
76 77
launch the Wine Windows API emulator (@url{http://www.winehq.org}) or
to ease cross-compilation and cross-debugging.
bellard's avatar
bellard committed
78 79 80

@end itemize

81
QEMU can run without a host kernel driver and yet gives acceptable
82
performance.
bellard's avatar
bellard committed
83

bellard's avatar
bellard committed
84 85
For system emulation, the following hardware targets are supported:
@itemize
86 87
@cindex emulated target systems
@cindex supported target systems
bellard's avatar
bellard committed
88
@item PC (x86 or x86_64 processor)
bellard's avatar
bellard committed
89
@item ISA PC (old style PC without PCI bus)
bellard's avatar
bellard committed
90
@item PREP (PowerPC processor)
91
@item G3 Beige PowerMac (PowerPC processor)
bellard's avatar
bellard committed
92
@item Mac99 PowerMac (PowerPC processor, in progress)
93
@item Sun4m/Sun4c/Sun4d (32-bit Sparc processor)
94
@item Sun4u/Sun4v (64-bit Sparc processor, in progress)
ths's avatar
ths committed
95
@item Malta board (32-bit and 64-bit MIPS processors)
96
@item MIPS Magnum (64-bit MIPS processor)
pbrook's avatar
pbrook committed
97 98
@item ARM Integrator/CP (ARM)
@item ARM Versatile baseboard (ARM)
Paul Brook's avatar
Paul Brook committed
99
@item ARM RealView Emulation/Platform baseboard (ARM)
100
@item Spitz, Akita, Borzoi, Terrier and Tosa PDAs (PXA270 processor)
pbrook's avatar
pbrook committed
101 102
@item Luminary Micro LM3S811EVB (ARM Cortex-M3)
@item Luminary Micro LM3S6965EVB (ARM Cortex-M3)
103
@item Freescale MCF5208EVB (ColdFire V2).
pbrook's avatar
pbrook committed
104
@item Arnewsh MCF5206 evaluation board (ColdFire V2).
105
@item Palm Tungsten|E PDA (OMAP310 processor)
106
@item N800 and N810 tablets (OMAP2420 processor)
107
@item MusicPal (MV88W8618 ARM processor)
108 109
@item Gumstix "Connex" and "Verdex" motherboards (PXA255/270).
@item Siemens SX1 smartphone (OMAP310 processor)
110 111
@item AXIS-Devboard88 (CRISv32 ETRAX-FS).
@item Petalogix Spartan 3aDSP1800 MMU ref design (MicroBlaze).
112
@item Avnet LX60/LX110/LX200 boards (Xtensa)
bellard's avatar
bellard committed
113
@end itemize
bellard's avatar
bellard committed
114

115 116 117 118
@cindex supported user mode targets
For user emulation, x86 (32 and 64 bit), PowerPC (32 and 64 bit),
ARM, MIPS (32 bit only), Sparc (32 and 64 bit),
Alpha, ColdFire(m68k), CRISv32 and MicroBlaze CPUs are supported.
bellard's avatar
bellard committed
119

120
@node Installation
bellard's avatar
bellard committed
121 122
@chapter Installation

bellard's avatar
bellard committed
123 124
If you want to compile QEMU yourself, see @ref{compilation}.

125 126 127 128 129 130 131
@menu
* install_linux::   Linux
* install_windows:: Windows
* install_mac::     Macintosh
@end menu

@node install_linux
bellard's avatar
bellard committed
132
@section Linux
133
@cindex installation (Linux)
bellard's avatar
bellard committed
134

bellard's avatar
bellard committed
135 136
If a precompiled package is available for your distribution - you just
have to install it. Otherwise, see @ref{compilation}.
bellard's avatar
bellard committed
137

138
@node install_windows
bellard's avatar
bellard committed
139
@section Windows
140
@cindex installation (Windows)
bellard's avatar
bellard committed
141

bellard's avatar
bellard committed
142
Download the experimental binary installer at
143
@url{http://www.free.oszoo.org/@/download.html}.
144
TODO (no longer available)
145

146
@node install_mac
bellard's avatar
bellard committed
147
@section Mac OS X
148

bellard's avatar
bellard committed
149
Download the experimental binary installer at
150
@url{http://www.free.oszoo.org/@/download.html}.
151
TODO (no longer available)
bellard's avatar
bellard committed
152

153
@node QEMU PC System emulator
bellard's avatar
bellard committed
154
@chapter QEMU PC System emulator
155
@cindex system emulation (PC)
bellard's avatar
bellard committed
156

157 158 159 160 161 162 163 164
@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
165
* pcsys_other_devs::   Other Devices
166 167
* direct_linux_boot::  Direct Linux Boot
* pcsys_usb::          USB emulation
168
* vnc_security::       VNC security
169 170 171 172 173
* gdb_usage::          GDB usage
* pcsys_os_specific::  Target OS specific information
@end menu

@node pcsys_introduction
bellard's avatar
bellard committed
174 175 176 177
@section Introduction

@c man begin DESCRIPTION

bellard's avatar
bellard committed
178 179
The QEMU PC System emulator simulates the
following peripherals:
bellard's avatar
bellard committed
180 181

@itemize @minus
182
@item
bellard's avatar
bellard committed
183
i440FX host PCI bridge and PIIX3 PCI to ISA bridge
bellard's avatar
bellard committed
184
@item
bellard's avatar
bellard committed
185 186
Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
extensions (hardware level, including all non standard modes).
bellard's avatar
bellard committed
187 188
@item
PS/2 mouse and keyboard
189
@item
bellard's avatar
bellard committed
190
2 PCI IDE interfaces with hard disk and CD-ROM support
bellard's avatar
bellard committed
191 192
@item
Floppy disk
193
@item
194
PCI and ISA network adapters
bellard's avatar
bellard committed
195
@item
bellard's avatar
bellard committed
196 197
Serial ports
@item
bellard's avatar
bellard committed
198 199 200 201
Creative SoundBlaster 16 sound card
@item
ENSONIQ AudioPCI ES1370 sound card
@item
balrog's avatar
balrog committed
202 203
Intel 82801AA AC97 Audio compatible sound card
@item
204 205
Intel HD Audio Controller and HDA codec
@item
Stefan Weil's avatar
Stefan Weil committed
206
Adlib (OPL2) - Yamaha YM3812 compatible chip
bellard's avatar
bellard committed
207
@item
208 209
Gravis Ultrasound GF1 sound card
@item
malc's avatar
malc committed
210 211
CS4231A compatible sound card
@item
bellard's avatar
bellard committed
212
PCI UHCI USB controller and a virtual USB hub.
bellard's avatar
bellard committed
213 214
@end itemize

bellard's avatar
bellard committed
215 216
SMP is supported with up to 255 CPUs.

217
QEMU uses the PC BIOS from the Seabios project and the Plex86/Bochs LGPL
bellard's avatar
bellard committed
218 219
VGA BIOS.

bellard's avatar
bellard committed
220 221
QEMU uses YM3812 emulation by Tatsuyuki Satoh.

Stefan Weil's avatar
Stefan Weil committed
222
QEMU uses GUS emulation (GUSEMU32 @url{http://www.deinmeister.de/gusemu/})
223
by Tibor "TS" Schütz.
224

225
Note that, by default, GUS shares IRQ(7) with parallel ports and so
226
QEMU must be told to not have parallel ports to have working GUS.
227 228

@example
229
qemu-system-i386 dos.img -soundhw gus -parallel none
230 231 232 233
@end example

Alternatively:
@example
234
qemu-system-i386 dos.img -device gus,irq=5
235 236 237 238
@end example

Or some other unclaimed IRQ.

malc's avatar
malc committed
239 240
CS4231A is the chip used in Windows Sound System and GUSMAX products

bellard's avatar
bellard committed
241 242
@c man end

243
@node pcsys_quickstart
bellard's avatar
bellard committed
244
@section Quick Start
245
@cindex quick start
bellard's avatar
bellard committed
246

bellard's avatar
bellard committed
247
Download and uncompress the linux image (@file{linux.img}) and type:
bellard's avatar
bellard committed
248 249

@example
250
qemu-system-i386 linux.img
bellard's avatar
bellard committed
251 252 253 254
@end example

Linux should boot and give you a prompt.

bellard's avatar
bellard committed
255
@node sec_invocation
bellard's avatar
bellard committed
256 257 258
@section Invocation

@example
bellard's avatar
bellard committed
259
@c man begin SYNOPSIS
260
usage: qemu-system-i386 [options] [@var{disk_image}]
bellard's avatar
bellard committed
261
@c man end
bellard's avatar
bellard committed
262 263
@end example

bellard's avatar
bellard committed
264
@c man begin OPTIONS
blueswir1's avatar
blueswir1 committed
265 266
@var{disk_image} is a raw hard disk image for IDE hard disk 0. Some
targets do not need a disk image.
bellard's avatar
bellard committed
267

268
@include qemu-options.texi
bellard's avatar
bellard committed
269

bellard's avatar
bellard committed
270 271
@c man end

272
@node pcsys_keys
bellard's avatar
bellard committed
273 274 275 276
@section Keys

@c man begin OPTIONS

277 278 279 280 281
During the graphical emulation, you can use special key combinations to change
modes. The default key mappings are shown below, but if you use @code{-alt-grab}
then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt) and if you use
@code{-ctrl-grab} then the modifier is the right Ctrl key (instead of Ctrl-Alt):

bellard's avatar
bellard committed
282
@table @key
bellard's avatar
bellard committed
283
@item Ctrl-Alt-f
284
@kindex Ctrl-Alt-f
bellard's avatar
bellard committed
285
Toggle full screen
bellard's avatar
bellard committed
286

Jan Kiszka's avatar
Jan Kiszka committed
287 288 289 290 291 292 293 294
@item Ctrl-Alt-+
@kindex Ctrl-Alt-+
Enlarge the screen

@item Ctrl-Alt--
@kindex Ctrl-Alt--
Shrink the screen

295
@item Ctrl-Alt-u
296
@kindex Ctrl-Alt-u
297 298
Restore the screen's un-scaled dimensions

bellard's avatar
bellard committed
299
@item Ctrl-Alt-n
300
@kindex Ctrl-Alt-n
bellard's avatar
bellard committed
301 302 303 304 305 306 307 308
Switch to virtual console 'n'. Standard console mappings are:
@table @emph
@item 1
Target system display
@item 2
Monitor
@item 3
Serial port
bellard's avatar
bellard committed
309 310
@end table

bellard's avatar
bellard committed
311
@item Ctrl-Alt
312
@kindex Ctrl-Alt
bellard's avatar
bellard committed
313 314 315
Toggle mouse and keyboard grab.
@end table

316 317 318 319
@kindex Ctrl-Up
@kindex Ctrl-Down
@kindex Ctrl-PageUp
@kindex Ctrl-PageDown
bellard's avatar
bellard committed
320 321 322
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.

323
@kindex Ctrl-a h
bellard's avatar
bellard committed
324 325
During emulation, if you are using the @option{-nographic} option, use
@key{Ctrl-a h} to get terminal commands:
bellard's avatar
bellard committed
326 327

@table @key
bellard's avatar
bellard committed
328
@item Ctrl-a h
329
@kindex Ctrl-a h
blueswir1's avatar
blueswir1 committed
330
@item Ctrl-a ?
331
@kindex Ctrl-a ?
bellard's avatar
bellard committed
332
Print this help
333
@item Ctrl-a x
334
@kindex Ctrl-a x
ths's avatar
ths committed
335
Exit emulator
336
@item Ctrl-a s
337
@kindex Ctrl-a s
bellard's avatar
bellard committed
338
Save disk data back to file (if -snapshot)
ths's avatar
ths committed
339
@item Ctrl-a t
340
@kindex Ctrl-a t
blueswir1's avatar
blueswir1 committed
341
Toggle console timestamps
bellard's avatar
bellard committed
342
@item Ctrl-a b
343
@kindex Ctrl-a b
bellard's avatar
bellard committed
344
Send break (magic sysrq in Linux)
bellard's avatar
bellard committed
345
@item Ctrl-a c
346
@kindex Ctrl-a c
bellard's avatar
bellard committed
347
Switch between console and monitor
bellard's avatar
bellard committed
348
@item Ctrl-a Ctrl-a
349
@kindex Ctrl-a a
bellard's avatar
bellard committed
350
Send Ctrl-a
bellard's avatar
bellard committed
351
@end table
bellard's avatar
bellard committed
352 353 354 355
@c man end

@ignore

bellard's avatar
bellard committed
356 357 358 359 360 361 362 363 364 365 366
@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

367
@node pcsys_monitor
bellard's avatar
bellard committed
368
@section QEMU Monitor
369
@cindex QEMU monitor
bellard's avatar
bellard committed
370 371 372 373 374 375 376

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

@itemize @minus

@item
ths's avatar
ths committed
377
Remove or insert removable media images
378
(such as CD-ROM or floppies).
bellard's avatar
bellard committed
379

380
@item
bellard's avatar
bellard committed
381 382 383 384 385 386 387 388 389 390 391
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:

392
@include qemu-monitor.texi
bellard's avatar
bellard committed
393

bellard's avatar
bellard committed
394 395 396 397 398
@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{$}.
bellard's avatar
bellard committed
399

bellard's avatar
bellard committed
400 401 402
@node disk_images
@section Disk Images

403 404
Since version 0.6.1, QEMU supports many disk image formats, including
growable disk images (their size increase as non empty sectors are
bellard's avatar
bellard committed
405 406 407
written), compressed and encrypted disk images. Version 0.8.3 added
the new qcow2 disk image format which is essential to support VM
snapshots.
bellard's avatar
bellard committed
408

409 410 411
@menu
* disk_images_quickstart::    Quick start for disk image creation
* disk_images_snapshot_mode:: Snapshot mode
bellard's avatar
bellard committed
412
* vm_snapshots::              VM snapshots
413
* qemu_img_invocation::       qemu-img Invocation
414
* qemu_nbd_invocation::       qemu-nbd Invocation
415
* disk_images_formats::       Disk image file formats
bellard's avatar
bellard committed
416
* host_drives::               Using host drives
417
* disk_images_fat_images::    Virtual FAT disk images
418
* disk_images_nbd::           NBD access
419
* disk_images_sheepdog::      Sheepdog disk images
420
* disk_images_iscsi::         iSCSI LUNs
421
* disk_images_gluster::       GlusterFS disk images
422
* disk_images_ssh::           Secure Shell (ssh) disk images
423 424 425
@end menu

@node disk_images_quickstart
426 427 428
@subsection Quick start for disk image creation

You can create a disk image with the command:
bellard's avatar
bellard committed
429
@example
430
qemu-img create myimage.img mysize
bellard's avatar
bellard committed
431
@end example
432 433 434 435
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.

436
See @ref{qemu_img_invocation} for more information.
bellard's avatar
bellard committed
437

438
@node disk_images_snapshot_mode
bellard's avatar
bellard committed
439 440 441 442 443
@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
444 445
write back to the raw disk images by using the @code{commit} monitor
command (or @key{C-a s} in the serial console).
bellard's avatar
bellard committed
446

bellard's avatar
bellard committed
447 448 449 450 451 452 453 454 455 456 457
@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
bellard's avatar
bellard committed
458
snapshot in addition to its numerical ID.
bellard's avatar
bellard committed
459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480

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
bellard's avatar
bellard committed
481 482
disk space (otherwise each snapshot would need a full copy of all the
disk images).
bellard's avatar
bellard committed
483 484 485 486 487 488 489

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
490
@item
bellard's avatar
bellard committed
491 492
They cannot cope with removable devices if they are removed or
inserted after a snapshot is done.
493
@item
bellard's avatar
bellard committed
494 495 496 497
A few device drivers still have incomplete snapshot support so their
state is not saved or restored properly (in particular USB).
@end itemize

498 499
@node qemu_img_invocation
@subsection @code{qemu-img} Invocation
bellard's avatar
bellard committed
500

501
@include qemu-img.texi
bellard's avatar
bellard committed
502

503 504 505 506 507
@node qemu_nbd_invocation
@subsection @code{qemu-nbd} Invocation

@include qemu-nbd.texi

508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538
@node disk_images_formats
@subsection Disk image file formats

QEMU supports many image file formats that can be used with VMs as well as with
any of the tools (like @code{qemu-img}). This includes the preferred formats
raw and qcow2 as well as formats that are supported for compatibility with
older QEMU versions or other hypervisors.

Depending on the image format, different options can be passed to
@code{qemu-img create} and @code{qemu-img convert} using the @code{-o} option.
This section describes each format and the options that are supported for it.

@table @option
@item raw

Raw disk image format. This format has the advantage of
being simple and easily exportable to all other emulators. If your
file system supports @emph{holes} (for example in ext2 or ext3 on
Linux or NTFS on Windows), then only the written sectors will reserve
space. Use @code{qemu-img info} to know the real size used by the
image or @code{ls -ls} on Unix/Linux.

@item qcow2
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
on Windows), optional AES encryption, zlib based compression and
support of multiple VM snapshots.

Supported options:
@table @code
@item compat
539 540
Determines the qcow2 version to use. @code{compat=0.10} uses the
traditional image format that can be read by any QEMU since 0.10.
541
@code{compat=1.1} enables image format extensions that only QEMU 1.1 and
542 543
newer understand (this is the default). Amongst others, this includes
zero clusters, which allow efficient copy-on-read for sparse images.
544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656

@item backing_file
File name of a base image (see @option{create} subcommand)
@item backing_fmt
Image format of the base image
@item encryption
If this option is set to @code{on}, the image is encrypted.

Encryption uses the AES format which is very secure (128 bit keys). Use
a long password (16 characters) to get maximum protection.

@item cluster_size
Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
sizes can improve the image file size whereas larger cluster sizes generally
provide better performance.

@item preallocation
Preallocation mode (allowed values: off, metadata). An image with preallocated
metadata is initially larger but can improve performance when the image needs
to grow.

@item lazy_refcounts
If this option is set to @code{on}, reference count updates are postponed with
the goal of avoiding metadata I/O and improving performance. This is
particularly interesting with @option{cache=writethrough} which doesn't batch
metadata updates. The tradeoff is that after a host crash, the reference count
tables must be rebuilt, i.e. on the next open an (automatic) @code{qemu-img
check -r all} is required, which may take some time.

This option can only be enabled if @code{compat=1.1} is specified.

@end table

@item qed
Old QEMU image format with support for backing files and compact image files
(when your filesystem or transport medium does not support holes).

When converting QED images to qcow2, you might want to consider using the
@code{lazy_refcounts=on} option to get a more QED-like behaviour.

Supported options:
@table @code
@item backing_file
File name of a base image (see @option{create} subcommand).
@item backing_fmt
Image file format of backing file (optional).  Useful if the format cannot be
autodetected because it has no header, like some vhd/vpc files.
@item cluster_size
Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller
cluster sizes can improve the image file size whereas larger cluster sizes
generally provide better performance.
@item table_size
Changes the number of clusters per L1/L2 table (must be power-of-2 between 1
and 16).  There is normally no need to change this value but this option can be
used for performance benchmarking.
@end table

@item qcow
Old QEMU image format with support for backing files, compact image files,
encryption and compression.

Supported options:
@table @code
@item backing_file
File name of a base image (see @option{create} subcommand)
@item encryption
If this option is set to @code{on}, the image is encrypted.
@end table

@item cow
User Mode Linux Copy On Write image format. It is supported only for
compatibility with previous versions.
Supported options:
@table @code
@item backing_file
File name of a base image (see @option{create} subcommand)
@end table

@item vdi
VirtualBox 1.1 compatible image format.
Supported options:
@table @code
@item static
If this option is set to @code{on}, the image is created with metadata
preallocation.
@end table

@item vmdk
VMware 3 and 4 compatible image format.

Supported options:
@table @code
@item backing_file
File name of a base image (see @option{create} subcommand).
@item compat6
Create a VMDK version 6 image (instead of version 4)
@item subformat
Specifies which VMDK subformat to use. Valid options are
@code{monolithicSparse} (default),
@code{monolithicFlat},
@code{twoGbMaxExtentSparse},
@code{twoGbMaxExtentFlat} and
@code{streamOptimized}.
@end table

@item vpc
VirtualPC compatible image format (VHD).
Supported options:
@table @code
@item subformat
Specifies which VHD subformat to use. Valid options are
@code{dynamic} (default) and @code{fixed}.
@end table
657 658 659 660 661 662 663 664 665 666 667 668 669 670 671

@item VHDX
Hyper-V compatible image format (VHDX).
Supported options:
@table @code
@item subformat
Specifies which VHDX subformat to use. Valid options are
@code{dynamic} (default) and @code{fixed}.
@item block_state_zero
Force use of payload blocks of type 'ZERO'.
@item block_size
Block size; min 1 MB, max 256 MB.  0 means auto-calculate based on image size.
@item log_size
Log size; min 1 MB.
@end table
672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688
@end table

@subsubsection Read-only formats
More disk image file formats are supported in a read-only mode.
@table @option
@item bochs
Bochs images of @code{growing} type.
@item cloop
Linux Compressed Loop image, useful only to reuse directly compressed
CD-ROM images present for example in the Knoppix CD-ROMs.
@item dmg
Apple disk image.
@item parallels
Parallels disk image format.
@end table


bellard's avatar
bellard committed
689 690 691 692 693 694 695 696 697
@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
698
disk image filename provided you have enough privileges to access
bellard's avatar
bellard committed
699 700 701
it. For example, use @file{/dev/cdrom} to access to the CDROM or
@file{/dev/fd0} for the floppy.

bellard's avatar
bellard committed
702
@table @code
bellard's avatar
bellard committed
703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722
@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

723 724
@table @code
@item CD
725
The preferred syntax is the drive letter (e.g. @file{d:}). The
726 727
alternate syntax @file{\\.\d:} is supported. @file{/dev/cdrom} is
supported as an alias to the first CDROM drive.
bellard's avatar
bellard committed
728

ths's avatar
ths committed
729
Currently there is no specific code to handle removable media, so it
bellard's avatar
bellard committed
730 731
is better to use the @code{change} or @code{eject} monitor commands to
change or eject media.
732
@item Hard disks
733
Hard disks can be used with the syntax: @file{\\.\PhysicalDrive@var{N}}
734 735 736 737 738 739 740 741
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

bellard's avatar
bellard committed
742 743 744

@subsubsection Mac OS X

745
@file{/dev/cdrom} is an alias to the first CDROM.
bellard's avatar
bellard committed
746

ths's avatar
ths committed
747
Currently there is no specific code to handle removable media, so it
bellard's avatar
bellard committed
748 749 750
is better to use the @code{change} or @code{eject} monitor commands to
change or eject media.

751
@node disk_images_fat_images
bellard's avatar
bellard committed
752 753 754 755 756
@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:

757
@example
758
qemu-system-i386 linux.img -hdb fat:/my_directory
bellard's avatar
bellard committed
759 760 761 762 763 764 765 766
@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:

767
@example
768
qemu-system-i386 linux.img -fda fat:floppy:/my_directory
bellard's avatar
bellard committed
769 770 771 772 773
@end example

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

774
@example
775
qemu-system-i386 linux.img -fda fat:floppy:rw:/my_directory
bellard's avatar
bellard committed
776 777 778 779 780 781
@end example

What you should @emph{never} do:
@itemize
@item use non-ASCII filenames ;
@item use "-snapshot" together with ":rw:" ;
bellard's avatar
bellard committed
782 783
@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.
bellard's avatar
bellard committed
784 785
@end itemize

786 787 788 789 790 791 792
@node disk_images_nbd
@subsection NBD access

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

@example
Paolo Bonzini's avatar
Paolo Bonzini committed
793
qemu-system-i386 linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/
794 795 796 797 798 799
@end example

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

@example
Paolo Bonzini's avatar
Paolo Bonzini committed
800
qemu-system-i386 linux.img -hdb nbd+unix://?socket=/tmp/my_socket
801 802 803 804 805 806 807 808 809 810 811 812 813
@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

Paolo Bonzini's avatar
Paolo Bonzini committed
814
@noindent
815 816
and then you can use it with two guests:
@example
Paolo Bonzini's avatar
Paolo Bonzini committed
817 818
qemu-system-i386 linux1.img -hdb nbd+unix://?socket=/tmp/my_socket
qemu-system-i386 linux2.img -hdb nbd+unix://?socket=/tmp/my_socket
819 820
@end example

Paolo Bonzini's avatar
Paolo Bonzini committed
821 822
If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's
own embedded NBD server), you must specify an export name in the URI:
823
@example
Paolo Bonzini's avatar
Paolo Bonzini committed
824 825 826 827 828 829 830 831 832 833
qemu-system-i386 -cdrom nbd://localhost/debian-500-ppc-netinst
qemu-system-i386 -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst
@end example

The URI syntax for NBD is supported since QEMU 1.3.  An alternative syntax is
also available.  Here are some example of the older syntax:
@example
qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket
qemu-system-i386 -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst
834 835
@end example

836 837 838 839 840 841 842 843 844
@node disk_images_sheepdog
@subsection Sheepdog disk images

Sheepdog is a distributed storage system for QEMU.  It provides highly
available block level storage volumes that can be attached to
QEMU-based virtual machines.

You can create a Sheepdog disk image with the command:
@example
MORITA Kazutaka's avatar
MORITA Kazutaka committed
845
qemu-img create sheepdog:///@var{image} @var{size}
846 847 848 849 850 851 852
@end example
where @var{image} is the Sheepdog image name and @var{size} is its
size.

To import the existing @var{filename} to Sheepdog, you can use a
convert command.
@example
MORITA Kazutaka's avatar
MORITA Kazutaka committed
853
qemu-img convert @var{filename} sheepdog:///@var{image}
854 855 856 857
@end example

You can boot from the Sheepdog disk image with the command:
@example
MORITA Kazutaka's avatar
MORITA Kazutaka committed
858
qemu-system-i386 sheepdog:///@var{image}
859 860 861 862
@end example

You can also create a snapshot of the Sheepdog image like qcow2.
@example
MORITA Kazutaka's avatar
MORITA Kazutaka committed
863
qemu-img snapshot -c @var{tag} sheepdog:///@var{image}
864 865 866 867 868 869
@end example
where @var{tag} is a tag name of the newly created snapshot.

To boot from the Sheepdog snapshot, specify the tag name of the
snapshot.
@example
MORITA Kazutaka's avatar
MORITA Kazutaka committed
870
qemu-system-i386 sheepdog:///@var{image}#@var{tag}
871 872 873 874
@end example

You can create a cloned image from the existing snapshot.
@example
MORITA Kazutaka's avatar
MORITA Kazutaka committed
875
qemu-img create -b sheepdog:///@var{base}#@var{tag} sheepdog:///@var{image}
876 877 878 879
@end example
where @var{base} is a image name of the source snapshot and @var{tag}
is its tag name.

880 881 882 883 884 885
You can use an unix socket instead of an inet socket:

@example
qemu-system-i386 sheepdog+unix:///@var{image}?socket=@var{path}
@end example

886 887 888
If the Sheepdog daemon doesn't run on the local host, you need to
specify one of the Sheepdog servers to connect to.
@example
MORITA Kazutaka's avatar
MORITA Kazutaka committed
889 890
qemu-img create sheepdog://@var{hostname}:@var{port}/@var{image} @var{size}
qemu-system-i386 sheepdog://@var{hostname}:@var{port}/@var{image}
891 892
@end example

893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927
@node disk_images_iscsi
@subsection iSCSI LUNs

iSCSI is a popular protocol used to access SCSI devices across a computer
network.

There are two different ways iSCSI devices can be used by QEMU.

The first method is to mount the iSCSI LUN on the host, and make it appear as
any other ordinary SCSI device on the host and then to access this device as a
/dev/sd device from QEMU. How to do this differs between host OSes.

The second method involves using the iSCSI initiator that is built into
QEMU. This provides a mechanism that works the same way regardless of which
host OS you are running QEMU on. This section will describe this second method
of using iSCSI together with QEMU.

In QEMU, iSCSI devices are described using special iSCSI URLs

@example
URL syntax:
iscsi://[<username>[%<password>]@@]<host>[:<port>]/<target-iqn-name>/<lun>
@end example

Username and password are optional and only used if your target is set up
using CHAP authentication for access control.
Alternatively the username and password can also be set via environment
variables to have these not show up in the process list

@example
export LIBISCSI_CHAP_USERNAME=<username>
export LIBISCSI_CHAP_PASSWORD=<password>
iscsi://<host>/<target-iqn-name>/<lun>
@end example

928 929 930 931
Various session related parameters can be set via special options, either
in a configuration file provided via '-readconfig' or directly on the
command line.

932 933 934 935 936
If the initiator-name is not specified qemu will use a default name
of 'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the
virtual machine.


937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983
@example
Setting a specific initiator name to use when logging in to the target
-iscsi initiator-name=iqn.qemu.test:my-initiator
@end example

@example
Controlling which type of header digest to negotiate with the target
-iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
@end example

These can also be set via a configuration file
@example
[iscsi]
  user = "CHAP username"
  password = "CHAP password"
  initiator-name = "iqn.qemu.test:my-initiator"
  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
  header-digest = "CRC32C"
@end example


Setting the target name allows different options for different targets
@example
[iscsi "iqn.target.name"]
  user = "CHAP username"
  password = "CHAP password"
  initiator-name = "iqn.qemu.test:my-initiator"
  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
  header-digest = "CRC32C"
@end example


Howto use a configuration file to set iSCSI configuration options:
@example
cat >iscsi.conf <<EOF
[iscsi]
  user = "me"
  password = "my password"
  initiator-name = "iqn.qemu.test:my-initiator"
  header-digest = "CRC32C"
EOF

qemu-system-i386 -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
    -readconfig iscsi.conf
@end example


984 985 986 987 988 989 990 991 992 993 994 995 996 997
Howto set up a simple iSCSI target on loopback and accessing it via QEMU:
@example
This example shows how to set up an iSCSI target with one CDROM and one DISK
using the Linux STGT software target. This target is available on Red Hat based
systems as the package 'scsi-target-utils'.

tgtd --iscsi portal=127.0.0.1:3260
tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \
    -b /IMAGES/disk.img --device-type=disk
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \
    -b /IMAGES/cd.iso --device-type=cd
tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL

998 999
qemu-system-i386 -iscsi initiator-name=iqn.qemu.test:my-initiator \
    -boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
1000 1001 1002
    -cdrom iscsi://127.0.0.1/iqn.qemu.test/2
@end example

1003 1004
@node disk_images_gluster
@subsection GlusterFS disk images
1005

1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051
GlusterFS is an user space distributed file system.

You can boot from the GlusterFS disk image with the command:
@example
qemu-system-x86_64 -drive file=gluster[+@var{transport}]://[@var{server}[:@var{port}]]/@var{volname}/@var{image}[?socket=...]
@end example

@var{gluster} is the protocol.

@var{transport} specifies the transport type used to connect to gluster
management daemon (glusterd). Valid transport types are
tcp, unix and rdma. If a transport type isn't specified, then tcp
type is assumed.

@var{server} specifies the server where the volume file specification for
the given volume resides. This can be either hostname, ipv4 address
or ipv6 address. ipv6 address needs to be within square brackets [ ].
If transport type is unix, then @var{server} field should not be specifed.
Instead @var{socket} field needs to be populated with the path to unix domain
socket.

@var{port} is the port number on which glusterd is listening. This is optional
and if not specified, QEMU will send 0 which will make gluster to use the
default port. If the transport type is unix, then @var{port} should not be
specified.

@var{volname} is the name of the gluster volume which contains the disk image.

@var{image} is the path to the actual disk image that resides on gluster volume.

You can create a GlusterFS disk image with the command:
@example
qemu-img create gluster://@var{server}/@var{volname}/@var{image} @var{size}
@end example

Examples
@example
qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img
qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4/testvol/a.img
qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img
qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img
qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img
qemu-system-x86_64 -drive file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img
qemu-system-x86_64 -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket
qemu-system-x86_64 -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img
@end example
1052

1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094
@node disk_images_ssh
@subsection Secure Shell (ssh) disk images

You can access disk images located on a remote ssh server
by using the ssh protocol:

@example
qemu-system-x86_64 -drive file=ssh://[@var{user}@@]@var{server}[:@var{port}]/@var{path}[?host_key_check=@var{host_key_check}]
@end example

Alternative syntax using properties:

@example
qemu-system-x86_64 -drive file.driver=ssh[,file.user=@var{user}],file.host=@var{server}[,file.port=@var{port}],file.path=@var{path}[,file.host_key_check=@var{host_key_check}]
@end example

@var{ssh} is the protocol.

@var{user} is the remote user.  If not specified, then the local
username is tried.

@var{server} specifies the remote ssh server.  Any ssh server can be
used, but it must implement the sftp-server protocol.  Most Unix/Linux
systems should work without requiring any extra configuration.

@var{port} is the port number on which sshd is listening.  By default
the standard ssh port (22) is used.

@var{path} is the path to the disk image.

The optional @var{host_key_check} parameter controls how the remote
host's key is checked.  The default is @code{yes} which means to use
the local @file{.ssh/known_hosts} file.  Setting this to @code{no}
turns off known-hosts checking.  Or you can check that the host key
matches a specific fingerprint:
@code{host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8}
(@code{sha1:} can also be used as a prefix, but note that OpenSSH
tools only use MD5 to print fingerprints).

Currently authentication must be done using ssh-agent.  Other
authentication methods may be supported in future.

1095 1096 1097 1098 1099 1100 1101 1102 1103 1104
Note: Many ssh servers do not support an @code{fsync}-style operation.
The ssh driver cannot guarantee that disk flush requests are
obeyed, and this causes a risk of disk corruption if the remote
server or network goes down during writes.  The driver will
print a warning when @code{fsync} is not supported:

warning: ssh server @code{ssh.example.com:22} does not support fsync

With sufficiently new versions of libssh2 and OpenSSH, @code{fsync} is
supported.
1105

1106
@node pcsys_network
bellard's avatar
bellard committed
1107 1108
@section Network emulation

1109
QEMU can simulate several network cards (PCI or ISA cards on the PC
bellard's avatar
bellard committed
1110 1111 1112
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
1113
simulate large networks. For simpler usage, a non privileged user mode
bellard's avatar
bellard committed
1114 1115 1116 1117
network stack can replace the TAP device to have a basic network
connection.

@subsection VLANs
bellard's avatar
bellard committed
1118

bellard's avatar
bellard committed
1119 1120 1121 1122
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).
bellard's avatar
bellard committed
1123

bellard's avatar
bellard committed
1124 1125 1126 1127 1128
@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.
bellard's avatar
bellard committed
1129

bellard's avatar
bellard committed
1130 1131
@subsubsection Linux host

bellard's avatar
bellard committed
1132 1133 1134 1135
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
bellard's avatar
bellard committed
1136
that your host kernel supports the TAP network interfaces: the
bellard's avatar
bellard committed
1137 1138
device @file{/dev/net/tun} must be present.

bellard's avatar
bellard committed
1139 1140
See @ref{sec_invocation} to have examples of command lines using the
TAP network interfaces.
bellard's avatar
bellard committed
1141

bellard's avatar
bellard committed
1142 1143 1144 1145 1146 1147 1148
@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/}.

bellard's avatar
bellard committed
1149 1150
@subsection Using the user mode network stack

bellard's avatar
bellard committed
1151 1152
By using the option @option{-net user} (default configuration if no
@option{-net} option is specified), QEMU uses a completely user mode
1153
network stack (you don't need root privilege to use the virtual
bellard's avatar
bellard committed
1154
network). The virtual network configuration is the following:
bellard's avatar
bellard committed
1155 1156 1157

@example

bellard's avatar
bellard committed
1158 1159
         QEMU VLAN      <------>  Firewall/DHCP server <-----> Internet
                           |          (10.0.2.2)
bellard's avatar
bellard committed
1160
                           |
bellard's avatar
bellard committed
1161
                           ---->  DNS server (10.0.2.3)
1162
                           |
bellard's avatar
bellard committed
1163
                           ---->  SMB server (10.0.2.4)
bellard's avatar
bellard committed
1164 1165 1166 1167
@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
bellard's avatar
bellard committed
1168 1169
configure the network in the QEMU VM. The DHCP server assign addresses
to the hosts starting from 10.0.2.15.
bellard's avatar
bellard committed
1170 1171 1172 1173 1174

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.

bellard's avatar
bellard committed
1175
Note that @code{ping} is not supported reliably to the internet as it
1176
would require root privileges. It means you can only ping the local
bellard's avatar
bellard committed
1177 1178
router (10.0.2.2).

bellard's avatar
bellard committed
1179 1180 1181 1182 1183 1184
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.
bellard's avatar
bellard committed
1185

bellard's avatar
bellard committed
1186 1187 1188 1189 1190 1191
@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.

1192
@node pcsys_other_devs
1193 1194 1195 1196 1197 1198 1199 1200 1201 1202
@section Other Devices

@subsection Inter-VM Shared Memory device

With KVM enabled on a Linux host, a shared memory device is available.  Guests
map a POSIX shared memory region into the guest as a PCI device that enables
zero-copy communication to the application level of the guests.  The basic
syntax is:

@example
1203
qemu-system-i386 -device ivshmem,size=<size in format accepted by -m>[,shm=<shm name>]
1204 1205 1206 1207 1208 1209 1210 1211 1212
@end example

If desired, interrupts can be sent between guest VMs accessing the same shared
memory region.  Interrupt support requires using a shared memory server and
using a chardev socket to connect to it.  The code for the shared memory server
is qemu.git/contrib/ivshmem-server.  An example syntax when using the shared
memory server is:

@example
1213 1214 1215
qemu-system-i386 -device ivshmem,size=<size in format accepted by -m>[,chardev=<id>]
                 [,msi=on][,ioeventfd=on][,vectors=n][,role=peer|master]
qemu-system-i386 -chardev socket,path=<path>,id=<id>
1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235
@end example

When using the server, the guest will be assigned a VM ID (>=0) that allows guests
using the same server to communicate via interrupts.  Guests can read their
VM ID from a device register (see example code).  Since receiving the shared
memory region from the server is asynchronous, there is a (small) chance the
guest may boot before the shared memory is attached.  To allow an application
to ensure shared memory is attached, the VM ID register will return -1 (an
invalid VM ID) until the memory is attached.  Once the shared memory is
attached, the VM ID will return the guest's valid VM ID.  With these semantics,
the guest application can check to ensure the shared memory is attached to the
guest before proceeding.

The @option{role} argument can be set to either master or peer and will affect
how the shared memory is migrated.  With @option{role=master}, the guest will
copy the shared memory on migration to the destination host.  With
@option{role=peer}, the guest will not be able to migrate with the device attached.
With the @option{peer} case, the device should be detached and then reattached
after migration using the PCI hotplug support.

bellard's avatar
bellard committed
1236 1237
@node direct_linux_boot
@section Direct Linux Boot
bellard's avatar
bellard committed
1238 1239 1240

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
bellard's avatar
bellard committed
1241
kernel testing.
bellard's avatar
bellard committed
1242

bellard's avatar
bellard committed
1243
The syntax is:
bellard's avatar
bellard committed
1244
@example
1245
qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"
bellard's avatar
bellard committed
1246 1247
@end example

bellard's avatar
bellard committed
1248 1249 1250
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.
bellard's avatar
bellard committed
1251

bellard's avatar
bellard committed
1252 1253 1254
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.
bellard's avatar
bellard committed
1255

bellard's avatar
bellard committed
1256 1257 1258
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:
bellard's avatar
bellard committed
1259
@example
1260 1261
qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
                 -append "root=/dev/hda console=ttyS0" -nographic
bellard's avatar
bellard committed
1262 1263
@end example

bellard's avatar
bellard committed
1264 1265
Use @key{Ctrl-a c} to switch between the serial console and the
monitor (@pxref{pcsys_keys}).
bellard's avatar
bellard committed
1266

1267
@node pcsys_usb
bellard's avatar
bellard committed
1268 1269
@section USB emulation

pbrook's avatar
pbrook committed
1270 1271
QEMU emulates a PCI UHCI USB controller. You can virtually plug
virtual USB devices or real host USB devices (experimental, works only
1272
on Linux hosts).  QEMU will automatically create and connect virtual USB hubs
bellard's avatar
bellard committed
1273
as necessary to connect multiple USB devices.
bellard's avatar
bellard committed
1274

pbrook's avatar
pbrook committed
1275 1276 1277 1278 1279 1280
@menu
* usb_devices::
* host_usb_devices::
@end menu
@node usb_devices
@subsection Connecting USB devices
bellard's avatar
bellard committed
1281

pbrook's avatar
pbrook committed
1282 1283
USB devices can be connected with the @option{-usbdevice} commandline option
or the @code{usb_add} monitor command.  Available devices are:
bellard's avatar
bellard committed
1284

1285 1286
@table @code
@item mouse
pbrook's avatar
pbrook committed
1287
Virtual Mouse.  This will override the PS/2 mouse emulation when activated.
1288
@item tablet
bellard's avatar
typo  
bellard committed
1289
Pointer device that uses absolute coordinates (like a touchscreen).
1290
This means QEMU is able to report the mouse position without having
pbrook's avatar
pbrook committed
1291
to grab the mouse.  Also overrides the PS/2 mouse emulation when activated.
1292
@item disk:@var{file}
pbrook's avatar
pbrook committed
1293
Mass storage device based on @var{file} (@pxref{disk_images})
1294
@item host:@var{bus.addr}
pbrook's avatar
pbrook committed
1295 1296
Pass through the host device identified by @var{bus.addr}
(Linux only)
1297
@item host:@var{vendor_id:product_id}
pbrook's avatar
pbrook committed
1298 1299
Pass through the host device identified by @var{vendor_id:product_id}
(Linux only)
1300
@item wacom-tablet
1301 1302 1303
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.
1304
@item keyboard
balrog's avatar
balrog committed
1305
Standard USB keyboard.  Will override the PS/2 keyboard (if present).
1306 1307 1308 1309
@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
Stefan Weil's avatar
Stefan Weil committed
1310
used to override the default 0403:6001. For instance,
1311 1312 1313 1314 1315
@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).