1 \input texinfo @c -*- texinfo -*-
3 @setfilename qemu-doc.info
7 @documentencoding UTF-8
9 @settitle QEMU version @value{VERSION} User Documentation
16 * QEMU: (qemu-doc). The QEMU Emulator User Documentation.
23 @center @titlefont{QEMU version @value{VERSION}}
25 @center @titlefont{User Documentation}
36 * QEMU PC System emulator::
37 * QEMU System emulator for non PC targets::
39 * QEMU User space emulator::
40 * Implementation notes::
52 * intro_features:: Features
58 QEMU is a FAST! processor emulator using dynamic translation to
59 achieve good emulation speed.
61 @cindex operating modes
62 QEMU has two operating modes:
65 @cindex system emulation
66 @item Full system emulation. In this mode, QEMU emulates a full system (for
67 example a PC), including one or several processors and various
68 peripherals. It can be used to launch different Operating Systems
69 without rebooting the PC or to debug system code.
71 @cindex user mode emulation
72 @item User mode emulation. In this mode, QEMU can launch
73 processes compiled for one CPU on another CPU. It can be used to
74 launch the Wine Windows API emulator (@url{http://www.winehq.org}) or
75 to ease cross-compilation and cross-debugging.
79 QEMU has the following features:
82 @item QEMU can run without a host kernel driver and yet gives acceptable
83 performance. It uses dynamic translation to native code for reasonable speed,
84 with support for self-modifying code and precise exceptions.
86 @item It is portable to several operating systems (GNU/Linux, *BSD, Mac OS X,
87 Windows) and architectures.
89 @item It performs accurate software emulation of the FPU.
92 QEMU user mode emulation has the following features:
94 @item Generic Linux system call converter, including most ioctls.
96 @item clone() emulation using native CPU clone() to use Linux scheduler for threads.
98 @item Accurate signal handling by remapping host signals to target signals.
101 QEMU full system emulation has the following features:
104 QEMU uses a full software MMU for maximum portability.
107 QEMU can optionally use an in-kernel accelerator, like kvm. The accelerators
108 execute most of the guest code natively, while
109 continuing to emulate the rest of the machine.
112 Various hardware devices can be emulated and in some cases, host
113 devices (e.g. serial and parallel ports, USB, drives) can be used
114 transparently by the guest Operating System. Host device passthrough
115 can be used for talking to external physical peripherals (e.g. a
116 webcam, modem or tape drive).
119 Symmetric multiprocessing (SMP) support. Currently, an in-kernel
120 accelerator is required to use more than one host CPU for emulation.
125 @node QEMU PC System emulator
126 @chapter QEMU PC System emulator
127 @cindex system emulation (PC)
130 * pcsys_introduction:: Introduction
131 * pcsys_quickstart:: Quick Start
132 * sec_invocation:: Invocation
133 * pcsys_keys:: Keys in the graphical frontends
134 * mux_keys:: Keys in the character backend multiplexer
135 * pcsys_monitor:: QEMU Monitor
136 * disk_images:: Disk Images
137 * pcsys_network:: Network emulation
138 * pcsys_other_devs:: Other Devices
139 * direct_linux_boot:: Direct Linux Boot
140 * pcsys_usb:: USB emulation
141 * vnc_security:: VNC security
142 * gdb_usage:: GDB usage
143 * pcsys_os_specific:: Target OS specific information
146 @node pcsys_introduction
147 @section Introduction
149 @c man begin DESCRIPTION
151 The QEMU PC System emulator simulates the
152 following peripherals:
156 i440FX host PCI bridge and PIIX3 PCI to ISA bridge
158 Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
159 extensions (hardware level, including all non standard modes).
161 PS/2 mouse and keyboard
163 2 PCI IDE interfaces with hard disk and CD-ROM support
167 PCI and ISA network adapters
171 IPMI BMC, either and internal or external one
173 Creative SoundBlaster 16 sound card
175 ENSONIQ AudioPCI ES1370 sound card
177 Intel 82801AA AC97 Audio compatible sound card
179 Intel HD Audio Controller and HDA codec
181 Adlib (OPL2) - Yamaha YM3812 compatible chip
183 Gravis Ultrasound GF1 sound card
185 CS4231A compatible sound card
187 PCI UHCI, OHCI, EHCI or XHCI USB controller and a virtual USB-1.1 hub.
190 SMP is supported with up to 255 CPUs.
192 QEMU uses the PC BIOS from the Seabios project and the Plex86/Bochs LGPL
195 QEMU uses YM3812 emulation by Tatsuyuki Satoh.
197 QEMU uses GUS emulation (GUSEMU32 @url{http://www.deinmeister.de/gusemu/})
198 by Tibor "TS" Schütz.
200 Note that, by default, GUS shares IRQ(7) with parallel ports and so
201 QEMU must be told to not have parallel ports to have working GUS.
204 qemu-system-i386 dos.img -soundhw gus -parallel none
209 qemu-system-i386 dos.img -device gus,irq=5
212 Or some other unclaimed IRQ.
214 CS4231A is the chip used in Windows Sound System and GUSMAX products
218 @node pcsys_quickstart
222 Download and uncompress the linux image (@file{linux.img}) and type:
225 qemu-system-i386 linux.img
228 Linux should boot and give you a prompt.
234 @c man begin SYNOPSIS
235 @command{qemu-system-i386} [@var{options}] [@var{disk_image}]
240 @var{disk_image} is a raw hard disk image for IDE hard disk 0. Some
241 targets do not need a disk image.
243 @include qemu-options.texi
248 @section Keys in the graphical frontends
252 During the graphical emulation, you can use special key combinations to change
253 modes. The default key mappings are shown below, but if you use @code{-alt-grab}
254 then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt) and if you use
255 @code{-ctrl-grab} then the modifier is the right Ctrl key (instead of Ctrl-Alt):
272 Restore the screen's un-scaled dimensions
276 Switch to virtual console 'n'. Standard console mappings are:
279 Target system display
288 Toggle mouse and keyboard grab.
294 @kindex Ctrl-PageDown
295 In the virtual consoles, you can use @key{Ctrl-Up}, @key{Ctrl-Down},
296 @key{Ctrl-PageUp} and @key{Ctrl-PageDown} to move in the back log.
301 @section Keys in the character backend multiplexer
305 During emulation, if you are using a character backend multiplexer
306 (which is the default if you are using @option{-nographic}) then
307 several commands are available via an escape sequence. These
308 key sequences all start with an escape character, which is @key{Ctrl-a}
309 by default, but can be changed with @option{-echr}. The list below assumes
310 you're using the default.
321 Save disk data back to file (if -snapshot)
324 Toggle console timestamps
327 Send break (magic sysrq in Linux)
330 Rotate between the frontends connected to the multiplexer (usually
331 this switches between the monitor and the console)
333 @kindex Ctrl-a Ctrl-a
334 Send the escape character to the frontend
341 The HTML documentation of QEMU for more precise information and Linux
342 user mode emulator invocation.
352 @section QEMU Monitor
355 The QEMU monitor is used to give complex commands to the QEMU
356 emulator. You can use it to:
361 Remove or insert removable media images
362 (such as CD-ROM or floppies).
365 Freeze/unfreeze the Virtual Machine (VM) and save or restore its state
368 @item Inspect the VM state without an external debugger.
374 The following commands are available:
376 @include qemu-monitor.texi
378 @include qemu-monitor-info.texi
380 @subsection Integer expressions
382 The monitor understands integers expressions for every integer
383 argument. You can use register names to get the value of specifics
384 CPU registers by prefixing them with @emph{$}.
389 QEMU supports many disk image formats, including growable disk images
390 (their size increase as non empty sectors are written), compressed and
391 encrypted disk images.
394 * disk_images_quickstart:: Quick start for disk image creation
395 * disk_images_snapshot_mode:: Snapshot mode
396 * vm_snapshots:: VM snapshots
397 * qemu_img_invocation:: qemu-img Invocation
398 * qemu_nbd_invocation:: qemu-nbd Invocation
399 * disk_images_formats:: Disk image file formats
400 * host_drives:: Using host drives
401 * disk_images_fat_images:: Virtual FAT disk images
402 * disk_images_nbd:: NBD access
403 * disk_images_sheepdog:: Sheepdog disk images
404 * disk_images_iscsi:: iSCSI LUNs
405 * disk_images_gluster:: GlusterFS disk images
406 * disk_images_ssh:: Secure Shell (ssh) disk images
409 @node disk_images_quickstart
410 @subsection Quick start for disk image creation
412 You can create a disk image with the command:
414 qemu-img create myimage.img mysize
416 where @var{myimage.img} is the disk image filename and @var{mysize} is its
417 size in kilobytes. You can add an @code{M} suffix to give the size in
418 megabytes and a @code{G} suffix for gigabytes.
420 See @ref{qemu_img_invocation} for more information.
422 @node disk_images_snapshot_mode
423 @subsection Snapshot mode
425 If you use the option @option{-snapshot}, all disk images are
426 considered as read only. When sectors in written, they are written in
427 a temporary file created in @file{/tmp}. You can however force the
428 write back to the raw disk images by using the @code{commit} monitor
429 command (or @key{C-a s} in the serial console).
432 @subsection VM snapshots
434 VM snapshots are snapshots of the complete virtual machine including
435 CPU state, RAM, device state and the content of all the writable
436 disks. In order to use VM snapshots, you must have at least one non
437 removable and writable block device using the @code{qcow2} disk image
438 format. Normally this device is the first virtual hard drive.
440 Use the monitor command @code{savevm} to create a new VM snapshot or
441 replace an existing one. A human readable name can be assigned to each
442 snapshot in addition to its numerical ID.
444 Use @code{loadvm} to restore a VM snapshot and @code{delvm} to remove
445 a VM snapshot. @code{info snapshots} lists the available snapshots
446 with their associated information:
449 (qemu) info snapshots
450 Snapshot devices: hda
451 Snapshot list (from hda):
452 ID TAG VM SIZE DATE VM CLOCK
453 1 start 41M 2006-08-06 12:38:02 00:00:14.954
454 2 40M 2006-08-06 12:43:29 00:00:18.633
455 3 msys 40M 2006-08-06 12:44:04 00:00:23.514
458 A VM snapshot is made of a VM state info (its size is shown in
459 @code{info snapshots}) and a snapshot of every writable disk image.
460 The VM state info is stored in the first @code{qcow2} non removable
461 and writable block device. The disk image snapshots are stored in
462 every disk image. The size of a snapshot in a disk image is difficult
463 to evaluate and is not shown by @code{info snapshots} because the
464 associated disk sectors are shared among all the snapshots to save
465 disk space (otherwise each snapshot would need a full copy of all the
468 When using the (unrelated) @code{-snapshot} option
469 (@ref{disk_images_snapshot_mode}), you can always make VM snapshots,
470 but they are deleted as soon as you exit QEMU.
472 VM snapshots currently have the following known limitations:
475 They cannot cope with removable devices if they are removed or
476 inserted after a snapshot is done.
478 A few device drivers still have incomplete snapshot support so their
479 state is not saved or restored properly (in particular USB).
482 @node qemu_img_invocation
483 @subsection @code{qemu-img} Invocation
485 @include qemu-img.texi
487 @node qemu_nbd_invocation
488 @subsection @code{qemu-nbd} Invocation
490 @include qemu-nbd.texi
492 @node disk_images_formats
493 @subsection Disk image file formats
495 QEMU supports many image file formats that can be used with VMs as well as with
496 any of the tools (like @code{qemu-img}). This includes the preferred formats
497 raw and qcow2 as well as formats that are supported for compatibility with
498 older QEMU versions or other hypervisors.
500 Depending on the image format, different options can be passed to
501 @code{qemu-img create} and @code{qemu-img convert} using the @code{-o} option.
502 This section describes each format and the options that are supported for it.
507 Raw disk image format. This format has the advantage of
508 being simple and easily exportable to all other emulators. If your
509 file system supports @emph{holes} (for example in ext2 or ext3 on
510 Linux or NTFS on Windows), then only the written sectors will reserve
511 space. Use @code{qemu-img info} to know the real size used by the
512 image or @code{ls -ls} on Unix/Linux.
517 Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
518 @code{falloc} mode preallocates space for image by calling posix_fallocate().
519 @code{full} mode preallocates space for image by writing zeros to underlying
524 QEMU image format, the most versatile format. Use it to have smaller
525 images (useful if your filesystem does not supports holes, for example
526 on Windows), zlib based compression and support of multiple VM
532 Determines the qcow2 version to use. @code{compat=0.10} uses the
533 traditional image format that can be read by any QEMU since 0.10.
534 @code{compat=1.1} enables image format extensions that only QEMU 1.1 and
535 newer understand (this is the default). Amongst others, this includes
536 zero clusters, which allow efficient copy-on-read for sparse images.
539 File name of a base image (see @option{create} subcommand)
541 Image format of the base image
543 This option is deprecated and equivalent to @code{encrypt.format=aes}
547 If this is set to @code{luks}, it requests that the qcow2 payload (not
548 qcow2 header) be encrypted using the LUKS format. The passphrase to
549 use to unlock the LUKS key slot is given by the @code{encrypt.key-secret}
550 parameter. LUKS encryption parameters can be tuned with the other
551 @code{encrypt.*} parameters.
553 If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.
554 The encryption key is given by the @code{encrypt.key-secret} parameter.
555 This encryption format is considered to be flawed by modern cryptography
556 standards, suffering from a number of design problems:
559 @item The AES-CBC cipher is used with predictable initialization vectors based
560 on the sector number. This makes it vulnerable to chosen plaintext attacks
561 which can reveal the existence of encrypted data.
562 @item The user passphrase is directly used as the encryption key. A poorly
563 chosen or short passphrase will compromise the security of the encryption.
564 @item In the event of the passphrase being compromised there is no way to
565 change the passphrase to protect data in any qcow images. The files must
566 be cloned, using a different encryption passphrase in the new file. The
567 original file must then be securely erased using a program like shred,
568 though even this is ineffective with many modern storage technologies.
571 The use of this is no longer supported in system emulators. Support only
572 remains in the command line utilities, for the purposes of data liberation
573 and interoperability with old versions of QEMU. The @code{luks} format
574 should be used instead.
576 @item encrypt.key-secret
578 Provides the ID of a @code{secret} object that contains the passphrase
579 (@code{encrypt.format=luks}) or encryption key (@code{encrypt.format=aes}).
581 @item encrypt.cipher-alg
583 Name of the cipher algorithm and key length. Currently defaults
584 to @code{aes-256}. Only used when @code{encrypt.format=luks}.
586 @item encrypt.cipher-mode
588 Name of the encryption mode to use. Currently defaults to @code{xts}.
589 Only used when @code{encrypt.format=luks}.
591 @item encrypt.ivgen-alg
593 Name of the initialization vector generator algorithm. Currently defaults
594 to @code{plain64}. Only used when @code{encrypt.format=luks}.
596 @item encrypt.ivgen-hash-alg
598 Name of the hash algorithm to use with the initialization vector generator
599 (if required). Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.
601 @item encrypt.hash-alg
603 Name of the hash algorithm to use for PBKDF algorithm
604 Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.
606 @item encrypt.iter-time
608 Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
609 Defaults to @code{2000}. Only used when @code{encrypt.format=luks}.
612 Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
613 sizes can improve the image file size whereas larger cluster sizes generally
614 provide better performance.
617 Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{falloc},
618 @code{full}). An image with preallocated metadata is initially larger but can
619 improve performance when the image needs to grow. @code{falloc} and @code{full}
620 preallocations are like the same options of @code{raw} format, but sets up
624 If this option is set to @code{on}, reference count updates are postponed with
625 the goal of avoiding metadata I/O and improving performance. This is
626 particularly interesting with @option{cache=writethrough} which doesn't batch
627 metadata updates. The tradeoff is that after a host crash, the reference count
628 tables must be rebuilt, i.e. on the next open an (automatic) @code{qemu-img
629 check -r all} is required, which may take some time.
631 This option can only be enabled if @code{compat=1.1} is specified.
634 If this option is set to @code{on}, it will turn off COW of the file. It's only
635 valid on btrfs, no effect on other file systems.
637 Btrfs has low performance when hosting a VM image file, even more when the guest
638 on the VM also using btrfs as file system. Turning off COW is a way to mitigate
639 this bad performance. Generally there are two ways to turn off COW on btrfs:
640 a) Disable it by mounting with nodatacow, then all newly created files will be
641 NOCOW. b) For an empty file, add the NOCOW file attribute. That's what this option
644 Note: this option is only valid to new or empty files. If there is an existing
645 file which is COW and has data blocks already, it couldn't be changed to NOCOW
646 by setting @code{nocow=on}. One can issue @code{lsattr filename} to check if
647 the NOCOW flag is set or not (Capital 'C' is NOCOW flag).
652 Old QEMU image format with support for backing files and compact image files
653 (when your filesystem or transport medium does not support holes).
655 When converting QED images to qcow2, you might want to consider using the
656 @code{lazy_refcounts=on} option to get a more QED-like behaviour.
661 File name of a base image (see @option{create} subcommand).
663 Image file format of backing file (optional). Useful if the format cannot be
664 autodetected because it has no header, like some vhd/vpc files.
666 Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller
667 cluster sizes can improve the image file size whereas larger cluster sizes
668 generally provide better performance.
670 Changes the number of clusters per L1/L2 table (must be power-of-2 between 1
671 and 16). There is normally no need to change this value but this option can be
672 used for performance benchmarking.
676 Old QEMU image format with support for backing files, compact image files,
677 encryption and compression.
682 File name of a base image (see @option{create} subcommand)
684 This option is deprecated and equivalent to @code{encrypt.format=aes}
687 If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.
688 The encryption key is given by the @code{encrypt.key-secret} parameter.
689 This encryption format is considered to be flawed by modern cryptography
690 standards, suffering from a number of design problems enumerated previously
691 against the @code{qcow2} image format.
693 The use of this is no longer supported in system emulators. Support only
694 remains in the command line utilities, for the purposes of data liberation
695 and interoperability with old versions of QEMU.
697 Users requiring native encryption should use the @code{qcow2} format
698 instead with @code{encrypt.format=luks}.
700 @item encrypt.key-secret
702 Provides the ID of a @code{secret} object that contains the encryption
703 key (@code{encrypt.format=aes}).
709 LUKS v1 encryption format, compatible with Linux dm-crypt/cryptsetup
716 Provides the ID of a @code{secret} object that contains the passphrase.
720 Name of the cipher algorithm and key length. Currently defaults
725 Name of the encryption mode to use. Currently defaults to @code{xts}.
729 Name of the initialization vector generator algorithm. Currently defaults
734 Name of the hash algorithm to use with the initialization vector generator
735 (if required). Defaults to @code{sha256}.
739 Name of the hash algorithm to use for PBKDF algorithm
740 Defaults to @code{sha256}.
744 Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
745 Defaults to @code{2000}.
750 VirtualBox 1.1 compatible image format.
754 If this option is set to @code{on}, the image is created with metadata
759 VMware 3 and 4 compatible image format.
764 File name of a base image (see @option{create} subcommand).
766 Create a VMDK version 6 image (instead of version 4)
768 Specify vmdk virtual hardware version. Compat6 flag cannot be enabled
769 if hwversion is specified.
771 Specifies which VMDK subformat to use. Valid options are
772 @code{monolithicSparse} (default),
773 @code{monolithicFlat},
774 @code{twoGbMaxExtentSparse},
775 @code{twoGbMaxExtentFlat} and
776 @code{streamOptimized}.
780 VirtualPC compatible image format (VHD).
784 Specifies which VHD subformat to use. Valid options are
785 @code{dynamic} (default) and @code{fixed}.
789 Hyper-V compatible image format (VHDX).
793 Specifies which VHDX subformat to use. Valid options are
794 @code{dynamic} (default) and @code{fixed}.
795 @item block_state_zero
796 Force use of payload blocks of type 'ZERO'. Can be set to @code{on} (default)
797 or @code{off}. When set to @code{off}, new blocks will be created as
798 @code{PAYLOAD_BLOCK_NOT_PRESENT}, which means parsers are free to return
799 arbitrary data for those blocks. Do not set to @code{off} when using
800 @code{qemu-img convert} with @code{subformat=dynamic}.
802 Block size; min 1 MB, max 256 MB. 0 means auto-calculate based on image size.
808 @subsubsection Read-only formats
809 More disk image file formats are supported in a read-only mode.
812 Bochs images of @code{growing} type.
814 Linux Compressed Loop image, useful only to reuse directly compressed
815 CD-ROM images present for example in the Knoppix CD-ROMs.
819 Parallels disk image format.
824 @subsection Using host drives
826 In addition to disk image files, QEMU can directly access host
827 devices. We describe here the usage for QEMU version >= 0.8.3.
831 On Linux, you can directly use the host device filename instead of a
832 disk image filename provided you have enough privileges to access
833 it. For example, use @file{/dev/cdrom} to access to the CDROM.
837 You can specify a CDROM device even if no CDROM is loaded. QEMU has
838 specific code to detect CDROM insertion or removal. CDROM ejection by
839 the guest OS is supported. Currently only data CDs are supported.
841 You can specify a floppy device even if no floppy is loaded. Floppy
842 removal is currently not detected accurately (if you change floppy
843 without doing floppy access while the floppy is not loaded, the guest
844 OS will think that the same floppy is loaded).
845 Use of the host's floppy device is deprecated, and support for it will
846 be removed in a future release.
848 Hard disks can be used. Normally you must specify the whole disk
849 (@file{/dev/hdb} instead of @file{/dev/hdb1}) so that the guest OS can
850 see it as a partitioned disk. WARNING: unless you know what you do, it
851 is better to only make READ-ONLY accesses to the hard disk otherwise
852 you may corrupt your host data (use the @option{-snapshot} command
853 line option or modify the device permissions accordingly).
856 @subsubsection Windows
860 The preferred syntax is the drive letter (e.g. @file{d:}). The
861 alternate syntax @file{\\.\d:} is supported. @file{/dev/cdrom} is
862 supported as an alias to the first CDROM drive.
864 Currently there is no specific code to handle removable media, so it
865 is better to use the @code{change} or @code{eject} monitor commands to
866 change or eject media.
868 Hard disks can be used with the syntax: @file{\\.\PhysicalDrive@var{N}}
869 where @var{N} is the drive number (0 is the first hard disk).
870 @file{/dev/hda} is supported as an alias to
871 the first hard disk drive @file{\\.\PhysicalDrive0}.
873 WARNING: unless you know what you do, it is better to only make
874 READ-ONLY accesses to the hard disk otherwise you may corrupt your
875 host data (use the @option{-snapshot} command line so that the
876 modifications are written in a temporary file).
880 @subsubsection Mac OS X
882 @file{/dev/cdrom} is an alias to the first CDROM.
884 Currently there is no specific code to handle removable media, so it
885 is better to use the @code{change} or @code{eject} monitor commands to
886 change or eject media.
888 @node disk_images_fat_images
889 @subsection Virtual FAT disk images
891 QEMU can automatically create a virtual FAT disk image from a
892 directory tree. In order to use it, just type:
895 qemu-system-i386 linux.img -hdb fat:/my_directory
898 Then you access access to all the files in the @file{/my_directory}
899 directory without having to copy them in a disk image or to export
900 them via SAMBA or NFS. The default access is @emph{read-only}.
902 Floppies can be emulated with the @code{:floppy:} option:
905 qemu-system-i386 linux.img -fda fat:floppy:/my_directory
908 A read/write support is available for testing (beta stage) with the
912 qemu-system-i386 linux.img -fda fat:floppy:rw:/my_directory
915 What you should @emph{never} do:
917 @item use non-ASCII filenames ;
918 @item use "-snapshot" together with ":rw:" ;
919 @item expect it to work when loadvm'ing ;
920 @item write to the FAT directory on the host system while accessing it with the guest system.
923 @node disk_images_nbd
924 @subsection NBD access
926 QEMU can access directly to block device exported using the Network Block Device
930 qemu-system-i386 linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/
933 If the NBD server is located on the same host, you can use an unix socket instead
937 qemu-system-i386 linux.img -hdb nbd+unix://?socket=/tmp/my_socket
940 In this case, the block device must be exported using qemu-nbd:
943 qemu-nbd --socket=/tmp/my_socket my_disk.qcow2
946 The use of qemu-nbd allows sharing of a disk between several guests:
948 qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2
952 and then you can use it with two guests:
954 qemu-system-i386 linux1.img -hdb nbd+unix://?socket=/tmp/my_socket
955 qemu-system-i386 linux2.img -hdb nbd+unix://?socket=/tmp/my_socket
958 If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's
959 own embedded NBD server), you must specify an export name in the URI:
961 qemu-system-i386 -cdrom nbd://localhost/debian-500-ppc-netinst
962 qemu-system-i386 -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst
965 The URI syntax for NBD is supported since QEMU 1.3. An alternative syntax is
966 also available. Here are some example of the older syntax:
968 qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
969 qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket
970 qemu-system-i386 -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst
973 @node disk_images_sheepdog
974 @subsection Sheepdog disk images
976 Sheepdog is a distributed storage system for QEMU. It provides highly
977 available block level storage volumes that can be attached to
978 QEMU-based virtual machines.
980 You can create a Sheepdog disk image with the command:
982 qemu-img create sheepdog:///@var{image} @var{size}
984 where @var{image} is the Sheepdog image name and @var{size} is its
987 To import the existing @var{filename} to Sheepdog, you can use a
990 qemu-img convert @var{filename} sheepdog:///@var{image}
993 You can boot from the Sheepdog disk image with the command:
995 qemu-system-i386 sheepdog:///@var{image}
998 You can also create a snapshot of the Sheepdog image like qcow2.
1000 qemu-img snapshot -c @var{tag} sheepdog:///@var{image}
1002 where @var{tag} is a tag name of the newly created snapshot.
1004 To boot from the Sheepdog snapshot, specify the tag name of the
1007 qemu-system-i386 sheepdog:///@var{image}#@var{tag}
1010 You can create a cloned image from the existing snapshot.
1012 qemu-img create -b sheepdog:///@var{base}#@var{tag} sheepdog:///@var{image}
1014 where @var{base} is a image name of the source snapshot and @var{tag}
1017 You can use an unix socket instead of an inet socket:
1020 qemu-system-i386 sheepdog+unix:///@var{image}?socket=@var{path}
1023 If the Sheepdog daemon doesn't run on the local host, you need to
1024 specify one of the Sheepdog servers to connect to.
1026 qemu-img create sheepdog://@var{hostname}:@var{port}/@var{image} @var{size}
1027 qemu-system-i386 sheepdog://@var{hostname}:@var{port}/@var{image}
1030 @node disk_images_iscsi
1031 @subsection iSCSI LUNs
1033 iSCSI is a popular protocol used to access SCSI devices across a computer
1036 There are two different ways iSCSI devices can be used by QEMU.
1038 The first method is to mount the iSCSI LUN on the host, and make it appear as
1039 any other ordinary SCSI device on the host and then to access this device as a
1040 /dev/sd device from QEMU. How to do this differs between host OSes.
1042 The second method involves using the iSCSI initiator that is built into
1043 QEMU. This provides a mechanism that works the same way regardless of which
1044 host OS you are running QEMU on. This section will describe this second method
1045 of using iSCSI together with QEMU.
1047 In QEMU, iSCSI devices are described using special iSCSI URLs
1051 iscsi://[<username>[%<password>]@@]<host>[:<port>]/<target-iqn-name>/<lun>
1054 Username and password are optional and only used if your target is set up
1055 using CHAP authentication for access control.
1056 Alternatively the username and password can also be set via environment
1057 variables to have these not show up in the process list
1060 export LIBISCSI_CHAP_USERNAME=<username>
1061 export LIBISCSI_CHAP_PASSWORD=<password>
1062 iscsi://<host>/<target-iqn-name>/<lun>
1065 Various session related parameters can be set via special options, either
1066 in a configuration file provided via '-readconfig' or directly on the
1069 If the initiator-name is not specified qemu will use a default name
1070 of 'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the
1075 Setting a specific initiator name to use when logging in to the target
1076 -iscsi initiator-name=iqn.qemu.test:my-initiator
1080 Controlling which type of header digest to negotiate with the target
1081 -iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
1084 These can also be set via a configuration file
1087 user = "CHAP username"
1088 password = "CHAP password"
1089 initiator-name = "iqn.qemu.test:my-initiator"
1090 # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
1091 header-digest = "CRC32C"
1095 Setting the target name allows different options for different targets
1097 [iscsi "iqn.target.name"]
1098 user = "CHAP username"
1099 password = "CHAP password"
1100 initiator-name = "iqn.qemu.test:my-initiator"
1101 # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
1102 header-digest = "CRC32C"
1106 Howto use a configuration file to set iSCSI configuration options:
1108 cat >iscsi.conf <<EOF
1111 password = "my password"
1112 initiator-name = "iqn.qemu.test:my-initiator"
1113 header-digest = "CRC32C"
1116 qemu-system-i386 -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
1117 -readconfig iscsi.conf
1121 Howto set up a simple iSCSI target on loopback and accessing it via QEMU:
1123 This example shows how to set up an iSCSI target with one CDROM and one DISK
1124 using the Linux STGT software target. This target is available on Red Hat based
1125 systems as the package 'scsi-target-utils'.
1127 tgtd --iscsi portal=127.0.0.1:3260
1128 tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
1129 tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \
1130 -b /IMAGES/disk.img --device-type=disk
1131 tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \
1132 -b /IMAGES/cd.iso --device-type=cd
1133 tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL
1135 qemu-system-i386 -iscsi initiator-name=iqn.qemu.test:my-initiator \
1136 -boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
1137 -cdrom iscsi://127.0.0.1/iqn.qemu.test/2
1140 @node disk_images_gluster
1141 @subsection GlusterFS disk images
1143 GlusterFS is a user space distributed file system.
1145 You can boot from the GlusterFS disk image with the command:
1148 qemu-system-x86_64 -drive file=gluster[+@var{type}]://[@var{host}[:@var{port}]]/@var{volume}/@var{path}
1149 [?socket=...][,file.debug=9][,file.logfile=...]
1152 qemu-system-x86_64 'json:@{"driver":"qcow2",
1153 "file":@{"driver":"gluster",
1154 "volume":"testvol","path":"a.img","debug":9,"logfile":"...",
1155 "server":[@{"type":"tcp","host":"...","port":"..."@},
1156 @{"type":"unix","socket":"..."@}]@}@}'
1159 @var{gluster} is the protocol.
1161 @var{type} specifies the transport type used to connect to gluster
1162 management daemon (glusterd). Valid transport types are
1163 tcp and unix. In the URI form, if a transport type isn't specified,
1164 then tcp type is assumed.
1166 @var{host} specifies the server where the volume file specification for
1167 the given volume resides. This can be either a hostname or an ipv4 address.
1168 If transport type is unix, then @var{host} field should not be specified.
1169 Instead @var{socket} field needs to be populated with the path to unix domain
1172 @var{port} is the port number on which glusterd is listening. This is optional
1173 and if not specified, it defaults to port 24007. If the transport type is unix,
1174 then @var{port} should not be specified.
1176 @var{volume} is the name of the gluster volume which contains the disk image.
1178 @var{path} is the path to the actual disk image that resides on gluster volume.
1180 @var{debug} is the logging level of the gluster protocol driver. Debug levels
1181 are 0-9, with 9 being the most verbose, and 0 representing no debugging output.
1182 The default level is 4. The current logging levels defined in the gluster source
1183 are 0 - None, 1 - Emergency, 2 - Alert, 3 - Critical, 4 - Error, 5 - Warning,
1184 6 - Notice, 7 - Info, 8 - Debug, 9 - Trace
1186 @var{logfile} is a commandline option to mention log file path which helps in
1187 logging to the specified file and also help in persisting the gfapi logs. The
1193 You can create a GlusterFS disk image with the command:
1195 qemu-img create gluster://@var{host}/@var{volume}/@var{path} @var{size}
1200 qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img
1201 qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4/testvol/a.img
1202 qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img
1203 qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img
1204 qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img
1205 qemu-system-x86_64 -drive file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img
1206 qemu-system-x86_64 -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket
1207 qemu-system-x86_64 -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img
1208 qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img,file.debug=9,file.logfile=/var/log/qemu-gluster.log
1209 qemu-system-x86_64 'json:@{"driver":"qcow2",
1210 "file":@{"driver":"gluster",
1211 "volume":"testvol","path":"a.img",
1212 "debug":9,"logfile":"/var/log/qemu-gluster.log",
1213 "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@},
1214 @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}'
1215 qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
1216 file.debug=9,file.logfile=/var/log/qemu-gluster.log,
1217 file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
1218 file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
1221 @node disk_images_ssh
1222 @subsection Secure Shell (ssh) disk images
1224 You can access disk images located on a remote ssh server
1225 by using the ssh protocol:
1228 qemu-system-x86_64 -drive file=ssh://[@var{user}@@]@var{server}[:@var{port}]/@var{path}[?host_key_check=@var{host_key_check}]
1231 Alternative syntax using properties:
1234 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}]
1237 @var{ssh} is the protocol.
1239 @var{user} is the remote user. If not specified, then the local
1242 @var{server} specifies the remote ssh server. Any ssh server can be
1243 used, but it must implement the sftp-server protocol. Most Unix/Linux
1244 systems should work without requiring any extra configuration.
1246 @var{port} is the port number on which sshd is listening. By default
1247 the standard ssh port (22) is used.
1249 @var{path} is the path to the disk image.
1251 The optional @var{host_key_check} parameter controls how the remote
1252 host's key is checked. The default is @code{yes} which means to use
1253 the local @file{.ssh/known_hosts} file. Setting this to @code{no}
1254 turns off known-hosts checking. Or you can check that the host key
1255 matches a specific fingerprint:
1256 @code{host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8}
1257 (@code{sha1:} can also be used as a prefix, but note that OpenSSH
1258 tools only use MD5 to print fingerprints).
1260 Currently authentication must be done using ssh-agent. Other
1261 authentication methods may be supported in future.
1263 Note: Many ssh servers do not support an @code{fsync}-style operation.
1264 The ssh driver cannot guarantee that disk flush requests are
1265 obeyed, and this causes a risk of disk corruption if the remote
1266 server or network goes down during writes. The driver will
1267 print a warning when @code{fsync} is not supported:
1269 warning: ssh server @code{ssh.example.com:22} does not support fsync
1271 With sufficiently new versions of libssh2 and OpenSSH, @code{fsync} is
1275 @section Network emulation
1277 QEMU can simulate several network cards (PCI or ISA cards on the PC
1278 target) and can connect them to an arbitrary number of Virtual Local
1279 Area Networks (VLANs). Host TAP devices can be connected to any QEMU
1280 VLAN. VLAN can be connected between separate instances of QEMU to
1281 simulate large networks. For simpler usage, a non privileged user mode
1282 network stack can replace the TAP device to have a basic network
1287 QEMU simulates several VLANs. A VLAN can be symbolised as a virtual
1288 connection between several network devices. These devices can be for
1289 example QEMU virtual Ethernet cards or virtual Host ethernet devices
1292 @subsection Using TAP network interfaces
1294 This is the standard way to connect QEMU to a real network. QEMU adds
1295 a virtual network device on your host (called @code{tapN}), and you
1296 can then configure it as if it was a real ethernet card.
1298 @subsubsection Linux host
1300 As an example, you can download the @file{linux-test-xxx.tar.gz}
1301 archive and copy the script @file{qemu-ifup} in @file{/etc} and
1302 configure properly @code{sudo} so that the command @code{ifconfig}
1303 contained in @file{qemu-ifup} can be executed as root. You must verify
1304 that your host kernel supports the TAP network interfaces: the
1305 device @file{/dev/net/tun} must be present.
1307 See @ref{sec_invocation} to have examples of command lines using the
1308 TAP network interfaces.
1310 @subsubsection Windows host
1312 There is a virtual ethernet driver for Windows 2000/XP systems, called
1313 TAP-Win32. But it is not included in standard QEMU for Windows,
1314 so you will need to get it separately. It is part of OpenVPN package,
1315 so download OpenVPN from : @url{http://openvpn.net/}.
1317 @subsection Using the user mode network stack
1319 By using the option @option{-net user} (default configuration if no
1320 @option{-net} option is specified), QEMU uses a completely user mode
1321 network stack (you don't need root privilege to use the virtual
1322 network). The virtual network configuration is the following:
1326 QEMU VLAN <------> Firewall/DHCP server <-----> Internet
1329 ----> DNS server (10.0.2.3)
1331 ----> SMB server (10.0.2.4)
1334 The QEMU VM behaves as if it was behind a firewall which blocks all
1335 incoming connections. You can use a DHCP client to automatically
1336 configure the network in the QEMU VM. The DHCP server assign addresses
1337 to the hosts starting from 10.0.2.15.
1339 In order to check that the user mode network is working, you can ping
1340 the address 10.0.2.2 and verify that you got an address in the range
1341 10.0.2.x from the QEMU virtual DHCP server.
1343 Note that ICMP traffic in general does not work with user mode networking.
1344 @code{ping}, aka. ICMP echo, to the local router (10.0.2.2) shall work,
1345 however. If you're using QEMU on Linux >= 3.0, it can use unprivileged ICMP
1346 ping sockets to allow @code{ping} to the Internet. The host admin has to set
1347 the ping_group_range in order to grant access to those sockets. To allow ping
1348 for GID 100 (usually users group):
1351 echo 100 100 > /proc/sys/net/ipv4/ping_group_range
1354 When using the built-in TFTP server, the router is also the TFTP
1357 When using the @option{'-netdev user,hostfwd=...'} option, TCP or UDP
1358 connections can be redirected from the host to the guest. It allows for
1359 example to redirect X11, telnet or SSH connections.
1361 @subsection Connecting VLANs between QEMU instances
1363 Using the @option{-net socket} option, it is possible to make VLANs
1364 that span several QEMU instances. See @ref{sec_invocation} to have a
1367 @node pcsys_other_devs
1368 @section Other Devices
1370 @subsection Inter-VM Shared Memory device
1372 On Linux hosts, a shared memory device is available. The basic syntax
1376 qemu-system-x86_64 -device ivshmem-plain,memdev=@var{hostmem}
1379 where @var{hostmem} names a host memory backend. For a POSIX shared
1380 memory backend, use something like
1383 -object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=@var{hostmem}
1386 If desired, interrupts can be sent between guest VMs accessing the same shared
1387 memory region. Interrupt support requires using a shared memory server and
1388 using a chardev socket to connect to it. The code for the shared memory server
1389 is qemu.git/contrib/ivshmem-server. An example syntax when using the shared
1393 # First start the ivshmem server once and for all
1394 ivshmem-server -p @var{pidfile} -S @var{path} -m @var{shm-name} -l @var{shm-size} -n @var{vectors}
1396 # Then start your qemu instances with matching arguments
1397 qemu-system-x86_64 -device ivshmem-doorbell,vectors=@var{vectors},chardev=@var{id}
1398 -chardev socket,path=@var{path},id=@var{id}
1401 When using the server, the guest will be assigned a VM ID (>=0) that allows guests
1402 using the same server to communicate via interrupts. Guests can read their
1403 VM ID from a device register (see ivshmem-spec.txt).
1405 @subsubsection Migration with ivshmem
1407 With device property @option{master=on}, the guest will copy the shared
1408 memory on migration to the destination host. With @option{master=off},
1409 the guest will not be able to migrate with the device attached. In the
1410 latter case, the device should be detached and then reattached after
1411 migration using the PCI hotplug support.
1413 At most one of the devices sharing the same memory can be master. The
1414 master must complete migration before you plug back the other devices.
1416 @subsubsection ivshmem and hugepages
1418 Instead of specifying the <shm size> using POSIX shm, you may specify
1419 a memory backend that has hugepage support:
1422 qemu-system-x86_64 -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,id=mb1
1423 -device ivshmem-plain,memdev=mb1
1426 ivshmem-server also supports hugepages mount points with the
1427 @option{-m} memory path argument.
1429 @node direct_linux_boot
1430 @section Direct Linux Boot
1432 This section explains how to launch a Linux kernel inside QEMU without
1433 having to make a full bootable image. It is very useful for fast Linux
1438 qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"
1441 Use @option{-kernel} to provide the Linux kernel image and
1442 @option{-append} to give the kernel command line arguments. The
1443 @option{-initrd} option can be used to provide an INITRD image.
1445 When using the direct Linux boot, a disk image for the first hard disk
1446 @file{hda} is required because its boot sector is used to launch the
1449 If you do not need graphical output, you can disable it and redirect
1450 the virtual serial port and the QEMU monitor to the console with the
1451 @option{-nographic} option. The typical command line is:
1453 qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
1454 -append "root=/dev/hda console=ttyS0" -nographic
1457 Use @key{Ctrl-a c} to switch between the serial console and the
1458 monitor (@pxref{pcsys_keys}).
1461 @section USB emulation
1463 QEMU can emulate a PCI UHCI, OHCI, EHCI or XHCI USB controller. You can
1464 plug virtual USB devices or real host USB devices (only works with certain
1465 host operating systems). QEMU will automatically create and connect virtual
1466 USB hubs as necessary to connect multiple USB devices.
1470 * host_usb_devices::
1473 @subsection Connecting USB devices
1475 USB devices can be connected with the @option{-device usb-...} command line
1476 option or the @code{device_add} monitor command. Available devices are:
1480 Virtual Mouse. This will override the PS/2 mouse emulation when activated.
1482 Pointer device that uses absolute coordinates (like a touchscreen).
1483 This means QEMU is able to report the mouse position without having
1484 to grab the mouse. Also overrides the PS/2 mouse emulation when activated.
1485 @item usb-storage,drive=@var{drive_id}
1486 Mass storage device backed by @var{drive_id} (@pxref{disk_images})
1488 USB attached SCSI device, see
1489 @url{http://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
1492 Bulk-only transport storage device, see
1493 @url{http://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
1494 for details here, too
1495 @item usb-mtp,x-root=@var{dir}
1496 Media transfer protocol device, using @var{dir} as root of the file tree
1497 that is presented to the guest.
1498 @item usb-host,hostbus=@var{bus},hostaddr=@var{addr}
1499 Pass through the host device identified by @var{bus} and @var{addr}
1500 @item usb-host,vendorid=@var{vendor},productid=@var{product}
1501 Pass through the host device identified by @var{vendor} and @var{product} ID
1502 @item usb-wacom-tablet
1503 Virtual Wacom PenPartner tablet. This device is similar to the @code{tablet}
1504 above but it can be used with the tslib library because in addition to touch
1505 coordinates it reports touch pressure.
1507 Standard USB keyboard. Will override the PS/2 keyboard (if present).
1508 @item usb-serial,chardev=@var{id}
1509 Serial converter. This emulates an FTDI FT232BM chip connected to host character
1511 @item usb-braille,chardev=@var{id}
1512 Braille device. This will use BrlAPI to display the braille output on a real
1513 or fake device referenced by @var{id}.
1514 @item usb-net[,netdev=@var{id}]
1515 Network adapter that supports CDC ethernet and RNDIS protocols. @var{id}
1516 specifies a netdev defined with @code{-netdev @dots{},id=@var{id}}.
1517 For instance, user-mode networking can be used with
1519 qemu-system-i386 [...] -netdev user,id=net0 -device usb-net,netdev=net0
1522 Smartcard reader device
1526 Bluetooth dongle for the transport layer of HCI. It is connected to HCI
1527 scatternet 0 by default (corresponds to @code{-bt hci,vlan=0}).
1528 Note that the syntax for the @code{-device usb-bt-dongle} option is not as
1529 useful yet as it was with the legacy @code{-usbdevice} option. So to
1530 configure an USB bluetooth device, you might need to use
1531 "@code{-usbdevice bt}[:@var{hci-type}]" instead. This configures a
1532 bluetooth dongle whose type is specified in the same format as with
1533 the @option{-bt hci} option, @pxref{bt-hcis,,allowed HCI types}. If
1534 no type is given, the HCI logic corresponds to @code{-bt hci,vlan=0}.
1535 This USB device implements the USB Transport Layer of HCI. Example
1538 @command{qemu-system-i386} [...@var{OPTIONS}...] @option{-usbdevice} bt:hci,vlan=3 @option{-bt} device:keyboard,vlan=3
1542 @node host_usb_devices
1543 @subsection Using host USB devices on a Linux host
1545 WARNING: this is an experimental feature. QEMU will slow down when
1546 using it. USB devices requiring real time streaming (i.e. USB Video
1547 Cameras) are not supported yet.
1550 @item If you use an early Linux 2.4 kernel, verify that no Linux driver
1551 is actually using the USB device. A simple way to do that is simply to
1552 disable the corresponding kernel module by renaming it from @file{mydriver.o}
1553 to @file{mydriver.o.disabled}.
1555 @item Verify that @file{/proc/bus/usb} is working (most Linux distributions should enable it by default). You should see something like that:
1561 @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:
1563 chown -R myuid /proc/bus/usb
1566 @item Launch QEMU and do in the monitor:
1569 Device 1.2, speed 480 Mb/s
1570 Class 00: USB device 1234:5678, USB DISK
1572 You should see the list of the devices you can use (Never try to use
1573 hubs, it won't work).
1575 @item Add the device in QEMU by using:
1577 device_add usb-host,vendorid=0x1234,productid=0x5678
1580 Normally the guest OS should report that a new USB device is plugged.
1581 You can use the option @option{-device usb-host,...} to do the same.
1583 @item Now you can try to use the host USB device in QEMU.
1587 When relaunching QEMU, you may have to unplug and plug again the USB
1588 device to make it work again (this is a bug).
1591 @section VNC security
1593 The VNC server capability provides access to the graphical console
1594 of the guest VM across the network. This has a number of security
1595 considerations depending on the deployment scenarios.
1599 * vnc_sec_password::
1600 * vnc_sec_certificate::
1601 * vnc_sec_certificate_verify::
1602 * vnc_sec_certificate_pw::
1604 * vnc_sec_certificate_sasl::
1605 * vnc_generate_cert::
1609 @subsection Without passwords
1611 The simplest VNC server setup does not include any form of authentication.
1612 For this setup it is recommended to restrict it to listen on a UNIX domain
1613 socket only. For example
1616 qemu-system-i386 [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc
1619 This ensures that only users on local box with read/write access to that
1620 path can access the VNC server. To securely access the VNC server from a
1621 remote machine, a combination of netcat+ssh can be used to provide a secure
1624 @node vnc_sec_password
1625 @subsection With passwords
1627 The VNC protocol has limited support for password based authentication. Since
1628 the protocol limits passwords to 8 characters it should not be considered
1629 to provide high security. The password can be fairly easily brute-forced by
1630 a client making repeat connections. For this reason, a VNC server using password
1631 authentication should be restricted to only listen on the loopback interface
1632 or UNIX domain sockets. Password authentication is not supported when operating
1633 in FIPS 140-2 compliance mode as it requires the use of the DES cipher. Password
1634 authentication is requested with the @code{password} option, and then once QEMU
1635 is running the password is set with the monitor. Until the monitor is used to
1636 set the password all clients will be rejected.
1639 qemu-system-i386 [...OPTIONS...] -vnc :1,password -monitor stdio
1640 (qemu) change vnc password
1645 @node vnc_sec_certificate
1646 @subsection With x509 certificates
1648 The QEMU VNC server also implements the VeNCrypt extension allowing use of
1649 TLS for encryption of the session, and x509 certificates for authentication.
1650 The use of x509 certificates is strongly recommended, because TLS on its
1651 own is susceptible to man-in-the-middle attacks. Basic x509 certificate
1652 support provides a secure session, but no authentication. This allows any
1653 client to connect, and provides an encrypted session.
1656 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509=/etc/pki/qemu -monitor stdio
1659 In the above example @code{/etc/pki/qemu} should contain at least three files,
1660 @code{ca-cert.pem}, @code{server-cert.pem} and @code{server-key.pem}. Unprivileged
1661 users will want to use a private directory, for example @code{$HOME/.pki/qemu}.
1662 NB the @code{server-key.pem} file should be protected with file mode 0600 to
1663 only be readable by the user owning it.
1665 @node vnc_sec_certificate_verify
1666 @subsection With x509 certificates and client verification
1668 Certificates can also provide a means to authenticate the client connecting.
1669 The server will request that the client provide a certificate, which it will
1670 then validate against the CA certificate. This is a good choice if deploying
1671 in an environment with a private internal certificate authority.
1674 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509verify=/etc/pki/qemu -monitor stdio
1678 @node vnc_sec_certificate_pw
1679 @subsection With x509 certificates, client verification and passwords
1681 Finally, the previous method can be combined with VNC password authentication
1682 to provide two layers of authentication for clients.
1685 qemu-system-i386 [...OPTIONS...] -vnc :1,password,tls,x509verify=/etc/pki/qemu -monitor stdio
1686 (qemu) change vnc password
1693 @subsection With SASL authentication
1695 The SASL authentication method is a VNC extension, that provides an
1696 easily extendable, pluggable authentication method. This allows for
1697 integration with a wide range of authentication mechanisms, such as
1698 PAM, GSSAPI/Kerberos, LDAP, SQL databases, one-time keys and more.
1699 The strength of the authentication depends on the exact mechanism
1700 configured. If the chosen mechanism also provides a SSF layer, then
1701 it will encrypt the datastream as well.
1703 Refer to the later docs on how to choose the exact SASL mechanism
1704 used for authentication, but assuming use of one supporting SSF,
1705 then QEMU can be launched with:
1708 qemu-system-i386 [...OPTIONS...] -vnc :1,sasl -monitor stdio
1711 @node vnc_sec_certificate_sasl
1712 @subsection With x509 certificates and SASL authentication
1714 If the desired SASL authentication mechanism does not supported
1715 SSF layers, then it is strongly advised to run it in combination
1716 with TLS and x509 certificates. This provides securely encrypted
1717 data stream, avoiding risk of compromising of the security
1718 credentials. This can be enabled, by combining the 'sasl' option
1719 with the aforementioned TLS + x509 options:
1722 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509,sasl -monitor stdio
1726 @node vnc_generate_cert
1727 @subsection Generating certificates for VNC
1729 The GNU TLS packages provides a command called @code{certtool} which can
1730 be used to generate certificates and keys in PEM format. At a minimum it
1731 is necessary to setup a certificate authority, and issue certificates to
1732 each server. If using certificates for authentication, then each client
1733 will also need to be issued a certificate. The recommendation is for the
1734 server to keep its certificates in either @code{/etc/pki/qemu} or for
1735 unprivileged users in @code{$HOME/.pki/qemu}.
1739 * vnc_generate_server::
1740 * vnc_generate_client::
1742 @node vnc_generate_ca
1743 @subsubsection Setup the Certificate Authority
1745 This step only needs to be performed once per organization / organizational
1746 unit. First the CA needs a private key. This key must be kept VERY secret
1747 and secure. If this key is compromised the entire trust chain of the certificates
1748 issued with it is lost.
1751 # certtool --generate-privkey > ca-key.pem
1754 A CA needs to have a public certificate. For simplicity it can be a self-signed
1755 certificate, or one issue by a commercial certificate issuing authority. To
1756 generate a self-signed certificate requires one core piece of information, the
1757 name of the organization.
1760 # cat > ca.info <<EOF
1761 cn = Name of your organization
1765 # certtool --generate-self-signed \
1766 --load-privkey ca-key.pem
1767 --template ca.info \
1768 --outfile ca-cert.pem
1771 The @code{ca-cert.pem} file should be copied to all servers and clients wishing to utilize
1772 TLS support in the VNC server. The @code{ca-key.pem} must not be disclosed/copied at all.
1774 @node vnc_generate_server
1775 @subsubsection Issuing server certificates
1777 Each server (or host) needs to be issued with a key and certificate. When connecting
1778 the certificate is sent to the client which validates it against the CA certificate.
1779 The core piece of information for a server certificate is the hostname. This should
1780 be the fully qualified hostname that the client will connect with, since the client
1781 will typically also verify the hostname in the certificate. On the host holding the
1782 secure CA private key:
1785 # cat > server.info <<EOF
1786 organization = Name of your organization
1787 cn = server.foo.example.com
1792 # certtool --generate-privkey > server-key.pem
1793 # certtool --generate-certificate \
1794 --load-ca-certificate ca-cert.pem \
1795 --load-ca-privkey ca-key.pem \
1796 --load-privkey server-key.pem \
1797 --template server.info \
1798 --outfile server-cert.pem
1801 The @code{server-key.pem} and @code{server-cert.pem} files should now be securely copied
1802 to the server for which they were generated. The @code{server-key.pem} is security
1803 sensitive and should be kept protected with file mode 0600 to prevent disclosure.
1805 @node vnc_generate_client
1806 @subsubsection Issuing client certificates
1808 If the QEMU VNC server is to use the @code{x509verify} option to validate client
1809 certificates as its authentication mechanism, each client also needs to be issued
1810 a certificate. The client certificate contains enough metadata to uniquely identify
1811 the client, typically organization, state, city, building, etc. On the host holding
1812 the secure CA private key:
1815 # cat > client.info <<EOF
1819 organization = Name of your organization
1820 cn = client.foo.example.com
1825 # certtool --generate-privkey > client-key.pem
1826 # certtool --generate-certificate \
1827 --load-ca-certificate ca-cert.pem \
1828 --load-ca-privkey ca-key.pem \
1829 --load-privkey client-key.pem \
1830 --template client.info \
1831 --outfile client-cert.pem
1834 The @code{client-key.pem} and @code{client-cert.pem} files should now be securely
1835 copied to the client for which they were generated.
1838 @node vnc_setup_sasl
1840 @subsection Configuring SASL mechanisms
1842 The following documentation assumes use of the Cyrus SASL implementation on a
1843 Linux host, but the principals should apply to any other SASL impl. When SASL
1844 is enabled, the mechanism configuration will be loaded from system default
1845 SASL service config /etc/sasl2/qemu.conf. If running QEMU as an
1846 unprivileged user, an environment variable SASL_CONF_PATH can be used
1847 to make it search alternate locations for the service config.
1849 If the TLS option is enabled for VNC, then it will provide session encryption,
1850 otherwise the SASL mechanism will have to provide encryption. In the latter
1851 case the list of possible plugins that can be used is drastically reduced. In
1852 fact only the GSSAPI SASL mechanism provides an acceptable level of security
1853 by modern standards. Previous versions of QEMU referred to the DIGEST-MD5
1854 mechanism, however, it has multiple serious flaws described in detail in
1855 RFC 6331 and thus should never be used any more. The SCRAM-SHA-1 mechanism
1856 provides a simple username/password auth facility similar to DIGEST-MD5, but
1857 does not support session encryption, so can only be used in combination with
1860 When not using TLS the recommended configuration is
1864 keytab: /etc/qemu/krb5.tab
1867 This says to use the 'GSSAPI' mechanism with the Kerberos v5 protocol, with
1868 the server principal stored in /etc/qemu/krb5.tab. For this to work the
1869 administrator of your KDC must generate a Kerberos principal for the server,
1870 with a name of 'qemu/somehost.example.com@@EXAMPLE.COM' replacing
1871 'somehost.example.com' with the fully qualified host name of the machine
1872 running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm.
1874 When using TLS, if username+password authentication is desired, then a
1875 reasonable configuration is
1878 mech_list: scram-sha-1
1879 sasldb_path: /etc/qemu/passwd.db
1882 The saslpasswd2 program can be used to populate the passwd.db file with
1885 Other SASL configurations will be left as an exercise for the reader. Note that
1886 all mechanisms except GSSAPI, should be combined with use of TLS to ensure a
1887 secure data channel.
1892 QEMU has a primitive support to work with gdb, so that you can do
1893 'Ctrl-C' while the virtual machine is running and inspect its state.
1895 In order to use gdb, launch QEMU with the '-s' option. It will wait for a
1898 qemu-system-i386 -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
1899 -append "root=/dev/hda"
1900 Connected to host network interface: tun0
1901 Waiting gdb connection on port 1234
1904 Then launch gdb on the 'vmlinux' executable:
1909 In gdb, connect to QEMU:
1911 (gdb) target remote localhost:1234
1914 Then you can use gdb normally. For example, type 'c' to launch the kernel:
1919 Here are some useful tips in order to use gdb on system code:
1923 Use @code{info reg} to display all the CPU registers.
1925 Use @code{x/10i $eip} to display the code at the PC position.
1927 Use @code{set architecture i8086} to dump 16 bit code. Then use
1928 @code{x/10i $cs*16+$eip} to dump the code at the PC position.
1931 Advanced debugging options:
1933 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 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:
1935 @item maintenance packet qqemu.sstepbits
1937 This will display the MASK bits used to control the single stepping IE:
1939 (gdb) maintenance packet qqemu.sstepbits
1940 sending: "qqemu.sstepbits"
1941 received: "ENABLE=1,NOIRQ=2,NOTIMER=4"
1943 @item maintenance packet qqemu.sstep
1945 This will display the current value of the mask used when single stepping IE:
1947 (gdb) maintenance packet qqemu.sstep
1948 sending: "qqemu.sstep"
1951 @item maintenance packet Qqemu.sstep=HEX_VALUE
1953 This will change the single step mask, so if wanted to enable IRQs on the single step, but not timers, you would use:
1955 (gdb) maintenance packet Qqemu.sstep=0x5
1956 sending: "qemu.sstep=0x5"
1961 @node pcsys_os_specific
1962 @section Target OS specific information
1966 To have access to SVGA graphic modes under X11, use the @code{vesa} or
1967 the @code{cirrus} X11 driver. For optimal performances, use 16 bit
1968 color depth in the guest and the host OS.
1970 When using a 2.6 guest Linux kernel, you should add the option
1971 @code{clock=pit} on the kernel command line because the 2.6 Linux
1972 kernels make very strict real time clock checks by default that QEMU
1973 cannot simulate exactly.
1975 When using a 2.6 guest Linux kernel, verify that the 4G/4G patch is
1976 not activated because QEMU is slower with this patch. The QEMU
1977 Accelerator Module is also much slower in this case. Earlier Fedora
1978 Core 3 Linux kernel (< 2.6.9-1.724_FC3) were known to incorporate this
1979 patch by default. Newer kernels don't have it.
1983 If you have a slow host, using Windows 95 is better as it gives the
1984 best speed. Windows 2000 is also a good choice.
1986 @subsubsection SVGA graphic modes support
1988 QEMU emulates a Cirrus Logic GD5446 Video
1989 card. All Windows versions starting from Windows 95 should recognize
1990 and use this graphic card. For optimal performances, use 16 bit color
1991 depth in the guest and the host OS.
1993 If you are using Windows XP as guest OS and if you want to use high
1994 resolution modes which the Cirrus Logic BIOS does not support (i.e. >=
1995 1280x1024x16), then you should use the VESA VBE virtual graphic card
1996 (option @option{-std-vga}).
1998 @subsubsection CPU usage reduction
2000 Windows 9x does not correctly use the CPU HLT
2001 instruction. The result is that it takes host CPU cycles even when
2002 idle. You can install the utility from
2003 @url{http://web.archive.org/web/20060212132151/http://www.user.cityline.ru/~maxamn/amnhltm.zip}
2004 to solve this problem. Note that no such tool is needed for NT, 2000 or XP.
2006 @subsubsection Windows 2000 disk full problem
2008 Windows 2000 has a bug which gives a disk full problem during its
2009 installation. When installing it, use the @option{-win2k-hack} QEMU
2010 option to enable a specific workaround. After Windows 2000 is
2011 installed, you no longer need this option (this option slows down the
2014 @subsubsection Windows 2000 shutdown
2016 Windows 2000 cannot automatically shutdown in QEMU although Windows 98
2017 can. It comes from the fact that Windows 2000 does not automatically
2018 use the APM driver provided by the BIOS.
2020 In order to correct that, do the following (thanks to Struan
2021 Bartlett): go to the Control Panel => Add/Remove Hardware & Next =>
2022 Add/Troubleshoot a device => Add a new device & Next => No, select the
2023 hardware from a list & Next => NT Apm/Legacy Support & Next => Next
2024 (again) a few times. Now the driver is installed and Windows 2000 now
2025 correctly instructs QEMU to shutdown at the appropriate moment.
2027 @subsubsection Share a directory between Unix and Windows
2029 See @ref{sec_invocation} about the help of the option
2030 @option{'-netdev user,smb=...'}.
2032 @subsubsection Windows XP security problem
2034 Some releases of Windows XP install correctly but give a security
2037 A problem is preventing Windows from accurately checking the
2038 license for this computer. Error code: 0x800703e6.
2041 The workaround is to install a service pack for XP after a boot in safe
2042 mode. Then reboot, and the problem should go away. Since there is no
2043 network while in safe mode, its recommended to download the full
2044 installation of SP1 or SP2 and transfer that via an ISO or using the
2045 vvfat block device ("-hdb fat:directory_which_holds_the_SP").
2047 @subsection MS-DOS and FreeDOS
2049 @subsubsection CPU usage reduction
2051 DOS does not correctly use the CPU HLT instruction. The result is that
2052 it takes host CPU cycles even when idle. You can install the utility from
2053 @url{http://web.archive.org/web/20051222085335/http://www.vmware.com/software/dosidle210.zip}
2054 to solve this problem.
2056 @node QEMU System emulator for non PC targets
2057 @chapter QEMU System emulator for non PC targets
2059 QEMU is a generic emulator and it emulates many non PC
2060 machines. Most of the options are similar to the PC emulator. The
2061 differences are mentioned in the following sections.
2064 * PowerPC System emulator::
2065 * Sparc32 System emulator::
2066 * Sparc64 System emulator::
2067 * MIPS System emulator::
2068 * ARM System emulator::
2069 * ColdFire System emulator::
2070 * Cris System emulator::
2071 * Microblaze System emulator::
2072 * SH4 System emulator::
2073 * Xtensa System emulator::
2076 @node PowerPC System emulator
2077 @section PowerPC System emulator
2078 @cindex system emulation (PowerPC)
2080 Use the executable @file{qemu-system-ppc} to simulate a complete PREP
2081 or PowerMac PowerPC system.
2083 QEMU emulates the following PowerMac peripherals:
2087 UniNorth or Grackle PCI Bridge
2089 PCI VGA compatible card with VESA Bochs Extensions
2091 2 PMAC IDE interfaces with hard disk and CD-ROM support
2097 VIA-CUDA with ADB keyboard and mouse.
2100 QEMU emulates the following PREP peripherals:
2106 PCI VGA compatible card with VESA Bochs Extensions
2108 2 IDE interfaces with hard disk and CD-ROM support
2112 NE2000 network adapters
2116 PREP Non Volatile RAM
2118 PC compatible keyboard and mouse.
2121 QEMU uses the Open Hack'Ware Open Firmware Compatible BIOS.
2123 Since version 0.9.1, QEMU uses OpenBIOS @url{http://www.openbios.org/}
2124 for the g3beige and mac99 PowerMac machines. OpenBIOS is a free (GPL
2125 v2) portable firmware implementation. The goal is to implement a 100%
2126 IEEE 1275-1994 (referred to as Open Firmware) compliant firmware.
2128 @c man begin OPTIONS
2130 The following options are specific to the PowerPC emulation:
2134 @item -g @var{W}x@var{H}[x@var{DEPTH}]
2136 Set the initial VGA graphic mode. The default is 800x600x32.
2138 @item -prom-env @var{string}
2140 Set OpenBIOS variables in NVRAM, for example:
2143 qemu-system-ppc -prom-env 'auto-boot?=false' \
2144 -prom-env 'boot-device=hd:2,\yaboot' \
2145 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
2148 These variables are not used by Open Hack'Ware.
2154 @node Sparc32 System emulator
2155 @section Sparc32 System emulator
2156 @cindex system emulation (Sparc32)
2158 Use the executable @file{qemu-system-sparc} to simulate the following
2159 Sun4m architecture machines:
2174 SPARCstation Voyager
2181 The emulation is somewhat complete. SMP up to 16 CPUs is supported,
2182 but Linux limits the number of usable CPUs to 4.
2184 QEMU emulates the following sun4m peripherals:
2190 TCX or cgthree Frame buffer
2192 Lance (Am7990) Ethernet
2194 Non Volatile RAM M48T02/M48T08
2196 Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboard
2197 and power/reset logic
2199 ESP SCSI controller with hard disk and CD-ROM support
2201 Floppy drive (not on SS-600MP)
2203 CS4231 sound device (only on SS-5, not working yet)
2206 The number of peripherals is fixed in the architecture. Maximum
2207 memory size depends on the machine type, for SS-5 it is 256MB and for
2210 Since version 0.8.2, QEMU uses OpenBIOS
2211 @url{http://www.openbios.org/}. OpenBIOS is a free (GPL v2) portable
2212 firmware implementation. The goal is to implement a 100% IEEE
2213 1275-1994 (referred to as Open Firmware) compliant firmware.
2215 A sample Linux 2.6 series kernel and ram disk image are available on
2216 the QEMU web site. There are still issues with NetBSD and OpenBSD, but
2217 most kernel versions work. Please note that currently older Solaris kernels
2218 don't work probably due to interface issues between OpenBIOS and
2221 @c man begin OPTIONS
2223 The following options are specific to the Sparc32 emulation:
2227 @item -g @var{W}x@var{H}x[x@var{DEPTH}]
2229 Set the initial graphics mode. For TCX, the default is 1024x768x8 with the
2230 option of 1024x768x24. For cgthree, the default is 1024x768x8 with the option
2231 of 1152x900x8 for people who wish to use OBP.
2233 @item -prom-env @var{string}
2235 Set OpenBIOS variables in NVRAM, for example:
2238 qemu-system-sparc -prom-env 'auto-boot?=false' \
2239 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
2242 @item -M [SS-4|SS-5|SS-10|SS-20|SS-600MP|LX|Voyager|SPARCClassic] [|SPARCbook]
2244 Set the emulated machine type. Default is SS-5.
2250 @node Sparc64 System emulator
2251 @section Sparc64 System emulator
2252 @cindex system emulation (Sparc64)
2254 Use the executable @file{qemu-system-sparc64} to simulate a Sun4u
2255 (UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic
2256 Niagara (T1) machine. The Sun4u emulator is mostly complete, being
2257 able to run Linux, NetBSD and OpenBSD in headless (-nographic) mode. The
2258 Sun4v emulator is still a work in progress.
2260 The Niagara T1 emulator makes use of firmware and OS binaries supplied in the S10image/ directory
2261 of the OpenSPARC T1 project @url{http://download.oracle.com/technetwork/systems/opensparc/OpenSPARCT1_Arch.1.5.tar.bz2}
2262 and is able to boot the disk.s10hw2 Solaris image.
2264 qemu-system-sparc64 -M niagara -L /path-to/S10image/ \
2266 -drive if=pflash,readonly=on,file=/S10image/disk.s10hw2
2270 QEMU emulates the following peripherals:
2274 UltraSparc IIi APB PCI Bridge
2276 PCI VGA compatible card with VESA Bochs Extensions
2278 PS/2 mouse and keyboard
2280 Non Volatile RAM M48T59
2282 PC-compatible serial ports
2284 2 PCI IDE interfaces with hard disk and CD-ROM support
2289 @c man begin OPTIONS
2291 The following options are specific to the Sparc64 emulation:
2295 @item -prom-env @var{string}
2297 Set OpenBIOS variables in NVRAM, for example:
2300 qemu-system-sparc64 -prom-env 'auto-boot?=false'
2303 @item -M [sun4u|sun4v|niagara]
2305 Set the emulated machine type. The default is sun4u.
2311 @node MIPS System emulator
2312 @section MIPS System emulator
2313 @cindex system emulation (MIPS)
2315 Four executables cover simulation of 32 and 64-bit MIPS systems in
2316 both endian options, @file{qemu-system-mips}, @file{qemu-system-mipsel}
2317 @file{qemu-system-mips64} and @file{qemu-system-mips64el}.
2318 Five different machine types are emulated:
2322 A generic ISA PC-like machine "mips"
2324 The MIPS Malta prototype board "malta"
2326 An ACER Pica "pica61". This machine needs the 64-bit emulator.
2328 MIPS emulator pseudo board "mipssim"
2330 A MIPS Magnum R4000 machine "magnum". This machine needs the 64-bit emulator.
2333 The generic emulation is supported by Debian 'Etch' and is able to
2334 install Debian into a virtual disk image. The following devices are
2339 A range of MIPS CPUs, default is the 24Kf
2341 PC style serial port
2348 The Malta emulation supports the following devices:
2352 Core board with MIPS 24Kf CPU and Galileo system controller
2354 PIIX4 PCI/USB/SMbus controller
2356 The Multi-I/O chip's serial device
2358 PCI network cards (PCnet32 and others)
2360 Malta FPGA serial device
2362 Cirrus (default) or any other PCI VGA graphics card
2365 The ACER Pica emulation supports:
2371 PC-style IRQ and DMA controllers
2378 The mipssim pseudo board emulation provides an environment similar
2379 to what the proprietary MIPS emulator uses for running Linux.
2384 A range of MIPS CPUs, default is the 24Kf
2386 PC style serial port
2388 MIPSnet network emulation
2391 The MIPS Magnum R4000 emulation supports:
2397 PC-style IRQ controller
2407 @node ARM System emulator
2408 @section ARM System emulator
2409 @cindex system emulation (ARM)
2411 Use the executable @file{qemu-system-arm} to simulate a ARM
2412 machine. The ARM Integrator/CP board is emulated with the following
2417 ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
2421 SMC 91c111 Ethernet adapter
2423 PL110 LCD controller
2425 PL050 KMI with PS/2 keyboard and mouse.
2427 PL181 MultiMedia Card Interface with SD card.
2430 The ARM Versatile baseboard is emulated with the following devices:
2434 ARM926E, ARM1136 or Cortex-A8 CPU
2436 PL190 Vectored Interrupt Controller
2440 SMC 91c111 Ethernet adapter
2442 PL110 LCD controller
2444 PL050 KMI with PS/2 keyboard and mouse.
2446 PCI host bridge. Note the emulated PCI bridge only provides access to
2447 PCI memory space. It does not provide access to PCI IO space.
2448 This means some devices (eg. ne2k_pci NIC) are not usable, and others
2449 (eg. rtl8139 NIC) are only usable when the guest drivers use the memory
2450 mapped control registers.
2452 PCI OHCI USB controller.
2454 LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices.
2456 PL181 MultiMedia Card Interface with SD card.
2459 Several variants of the ARM RealView baseboard are emulated,
2460 including the EB, PB-A8 and PBX-A9. Due to interactions with the
2461 bootloader, only certain Linux kernel configurations work out
2462 of the box on these boards.
2464 Kernels for the PB-A8 board should have CONFIG_REALVIEW_HIGH_PHYS_OFFSET
2465 enabled in the kernel, and expect 512M RAM. Kernels for The PBX-A9 board
2466 should have CONFIG_SPARSEMEM enabled, CONFIG_REALVIEW_HIGH_PHYS_OFFSET
2467 disabled and expect 1024M RAM.
2469 The following devices are emulated:
2473 ARM926E, ARM1136, ARM11MPCore, Cortex-A8 or Cortex-A9 MPCore CPU
2475 ARM AMBA Generic/Distributed Interrupt Controller
2479 SMC 91c111 or SMSC LAN9118 Ethernet adapter
2481 PL110 LCD controller
2483 PL050 KMI with PS/2 keyboard and mouse
2487 PCI OHCI USB controller
2489 LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices
2491 PL181 MultiMedia Card Interface with SD card.
2494 The XScale-based clamshell PDA models ("Spitz", "Akita", "Borzoi"
2495 and "Terrier") emulation includes the following peripherals:
2499 Intel PXA270 System-on-chip (ARM V5TE core)
2503 IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in "Akita"
2505 On-chip OHCI USB controller
2507 On-chip LCD controller
2509 On-chip Real Time Clock
2511 TI ADS7846 touchscreen controller on SSP bus
2513 Maxim MAX1111 analog-digital converter on I@math{^2}C bus
2515 GPIO-connected keyboard controller and LEDs
2517 Secure Digital card connected to PXA MMC/SD host
2521 WM8750 audio CODEC on I@math{^2}C and I@math{^2}S busses
2524 The Palm Tungsten|E PDA (codename "Cheetah") emulation includes the
2529 Texas Instruments OMAP310 System-on-chip (ARM 925T core)
2531 ROM and RAM memories (ROM firmware image can be loaded with -option-rom)
2533 On-chip LCD controller
2535 On-chip Real Time Clock
2537 TI TSC2102i touchscreen controller / analog-digital converter / Audio
2538 CODEC, connected through MicroWire and I@math{^2}S busses
2540 GPIO-connected matrix keypad
2542 Secure Digital card connected to OMAP MMC/SD host
2547 Nokia N800 and N810 internet tablets (known also as RX-34 and RX-44 / 48)
2548 emulation supports the following elements:
2552 Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)
2554 RAM and non-volatile OneNAND Flash memories
2556 Display connected to EPSON remote framebuffer chip and OMAP on-chip
2557 display controller and a LS041y3 MIPI DBI-C controller
2559 TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen controllers
2560 driven through SPI bus
2562 National Semiconductor LM8323-controlled qwerty keyboard driven
2563 through I@math{^2}C bus
2565 Secure Digital card connected to OMAP MMC/SD host
2567 Three OMAP on-chip UARTs and on-chip STI debugging console
2569 A Bluetooth(R) transceiver and HCI connected to an UART
2571 Mentor Graphics "Inventra" dual-role USB controller embedded in a TI
2572 TUSB6010 chip - only USB host mode is supported
2574 TI TMP105 temperature sensor driven through I@math{^2}C bus
2576 TI TWL92230C power management companion with an RTC on I@math{^2}C bus
2578 Nokia RETU and TAHVO multi-purpose chips with an RTC, connected
2582 The Luminary Micro Stellaris LM3S811EVB emulation includes the following
2589 64k Flash and 8k SRAM.
2591 Timers, UARTs, ADC and I@math{^2}C interface.
2593 OSRAM Pictiva 96x16 OLED with SSD0303 controller on I@math{^2}C bus.
2596 The Luminary Micro Stellaris LM3S6965EVB emulation includes the following
2603 256k Flash and 64k SRAM.
2605 Timers, UARTs, ADC, I@math{^2}C and SSI interfaces.
2607 OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via SSI.
2610 The Freecom MusicPal internet radio emulation includes the following
2615 Marvell MV88W8618 ARM core.
2617 32 MB RAM, 256 KB SRAM, 8 MB flash.
2621 MV88W8xx8 Ethernet controller
2623 MV88W8618 audio controller, WM8750 CODEC and mixer
2625 128×64 display with brightness control
2627 2 buttons, 2 navigation wheels with button function
2630 The Siemens SX1 models v1 and v2 (default) basic emulation.
2631 The emulation includes the following elements:
2635 Texas Instruments OMAP310 System-on-chip (ARM 925T core)
2637 ROM and RAM memories (ROM firmware image can be loaded with -pflash)
2639 1 Flash of 16MB and 1 Flash of 8MB
2643 On-chip LCD controller
2645 On-chip Real Time Clock
2647 Secure Digital card connected to OMAP MMC/SD host
2652 A Linux 2.6 test image is available on the QEMU web site. More
2653 information is available in the QEMU mailing-list archive.
2655 @c man begin OPTIONS
2657 The following options are specific to the ARM emulation:
2662 Enable semihosting syscall emulation.
2664 On ARM this implements the "Angel" interface.
2666 Note that this allows guest direct access to the host filesystem,
2667 so should only be used with trusted guest OS.
2673 @node ColdFire System emulator
2674 @section ColdFire System emulator
2675 @cindex system emulation (ColdFire)
2676 @cindex system emulation (M68K)
2678 Use the executable @file{qemu-system-m68k} to simulate a ColdFire machine.
2679 The emulator is able to boot a uClinux kernel.
2681 The M5208EVB emulation includes the following devices:
2685 MCF5208 ColdFire V2 Microprocessor (ISA A+ with EMAC).
2687 Three Two on-chip UARTs.
2689 Fast Ethernet Controller (FEC)
2692 The AN5206 emulation includes the following devices:
2696 MCF5206 ColdFire V2 Microprocessor.
2701 @c man begin OPTIONS
2703 The following options are specific to the ColdFire emulation:
2708 Enable semihosting syscall emulation.
2710 On M68K this implements the "ColdFire GDB" interface used by libgloss.
2712 Note that this allows guest direct access to the host filesystem,
2713 so should only be used with trusted guest OS.
2719 @node Cris System emulator
2720 @section Cris System emulator
2721 @cindex system emulation (Cris)
2725 @node Microblaze System emulator
2726 @section Microblaze System emulator
2727 @cindex system emulation (Microblaze)
2731 @node SH4 System emulator
2732 @section SH4 System emulator
2733 @cindex system emulation (SH4)
2737 @node Xtensa System emulator
2738 @section Xtensa System emulator
2739 @cindex system emulation (Xtensa)
2741 Two executables cover simulation of both Xtensa endian options,
2742 @file{qemu-system-xtensa} and @file{qemu-system-xtensaeb}.
2743 Two different machine types are emulated:
2747 Xtensa emulator pseudo board "sim"
2749 Avnet LX60/LX110/LX200 board
2752 The sim pseudo board emulation provides an environment similar
2753 to one provided by the proprietary Tensilica ISS.
2758 A range of Xtensa CPUs, default is the DC232B
2760 Console and filesystem access via semihosting calls
2763 The Avnet LX60/LX110/LX200 emulation supports:
2767 A range of Xtensa CPUs, default is the DC232B
2771 OpenCores 10/100 Mbps Ethernet MAC
2774 @c man begin OPTIONS
2776 The following options are specific to the Xtensa emulation:
2781 Enable semihosting syscall emulation.
2783 Xtensa semihosting provides basic file IO calls, such as open/read/write/seek/select.
2784 Tensilica baremetal libc for ISS and linux platform "sim" use this interface.
2786 Note that this allows guest direct access to the host filesystem,
2787 so should only be used with trusted guest OS.
2793 @node QEMU Guest Agent
2794 @chapter QEMU Guest Agent invocation
2796 @include qemu-ga.texi
2798 @node QEMU User space emulator
2799 @chapter QEMU User space emulator
2802 * Supported Operating Systems ::
2804 * Linux User space emulator::
2805 * BSD User space emulator ::
2808 @node Supported Operating Systems
2809 @section Supported Operating Systems
2811 The following OS are supported in user space emulation:
2815 Linux (referred as qemu-linux-user)
2817 BSD (referred as qemu-bsd-user)
2823 QEMU user space emulation has the following notable features:
2826 @item System call translation:
2827 QEMU includes a generic system call translator. This means that
2828 the parameters of the system calls can be converted to fix
2829 endianness and 32/64-bit mismatches between hosts and targets.
2830 IOCTLs can be converted too.
2832 @item POSIX signal handling:
2833 QEMU can redirect to the running program all signals coming from
2834 the host (such as @code{SIGALRM}), as well as synthesize signals from
2835 virtual CPU exceptions (for example @code{SIGFPE} when the program
2836 executes a division by zero).
2838 QEMU relies on the host kernel to emulate most signal system
2839 calls, for example to emulate the signal mask. On Linux, QEMU
2840 supports both normal and real-time signals.
2843 On Linux, QEMU can emulate the @code{clone} syscall and create a real
2844 host thread (with a separate virtual CPU) for each emulated thread.
2845 Note that not all targets currently emulate atomic operations correctly.
2846 x86 and ARM use a global lock in order to preserve their semantics.
2849 QEMU was conceived so that ultimately it can emulate itself. Although
2850 it is not very useful, it is an important test to show the power of the
2853 @node Linux User space emulator
2854 @section Linux User space emulator
2859 * Command line options::
2864 @subsection Quick Start
2866 In order to launch a Linux process, QEMU needs the process executable
2867 itself and all the target (x86) dynamic libraries used by it.
2871 @item On x86, you can just try to launch any process by using the native
2875 qemu-i386 -L / /bin/ls
2878 @code{-L /} tells that the x86 dynamic linker must be searched with a
2881 @item Since QEMU is also a linux process, you can launch QEMU with
2882 QEMU (NOTE: you can only do that if you compiled QEMU from the sources):
2885 qemu-i386 -L / qemu-i386 -L / /bin/ls
2888 @item On non x86 CPUs, you need first to download at least an x86 glibc
2889 (@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
2890 @code{LD_LIBRARY_PATH} is not set:
2893 unset LD_LIBRARY_PATH
2896 Then you can launch the precompiled @file{ls} x86 executable:
2899 qemu-i386 tests/i386/ls
2901 You can look at @file{scripts/qemu-binfmt-conf.sh} so that
2902 QEMU is automatically launched by the Linux kernel when you try to
2903 launch x86 executables. It requires the @code{binfmt_misc} module in the
2906 @item The x86 version of QEMU is also included. You can try weird things such as:
2908 qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 \
2909 /usr/local/qemu-i386/bin/ls-i386
2915 @subsection Wine launch
2919 @item Ensure that you have a working QEMU with the x86 glibc
2920 distribution (see previous section). In order to verify it, you must be
2924 qemu-i386 /usr/local/qemu-i386/bin/ls-i386
2927 @item Download the binary x86 Wine install
2928 (@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page).
2930 @item Configure Wine on your account. Look at the provided script
2931 @file{/usr/local/qemu-i386/@/bin/wine-conf.sh}. Your previous
2932 @code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.
2934 @item Then you can try the example @file{putty.exe}:
2937 qemu-i386 /usr/local/qemu-i386/wine/bin/wine \
2938 /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
2943 @node Command line options
2944 @subsection Command line options
2947 @command{qemu-i386} [@option{-h]} [@option{-d]} [@option{-L} @var{path}] [@option{-s} @var{size}] [@option{-cpu} @var{model}] [@option{-g} @var{port}] [@option{-B} @var{offset}] [@option{-R} @var{size}] @var{program} [@var{arguments}...]
2954 Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
2956 Set the x86 stack size in bytes (default=524288)
2958 Select CPU model (-cpu help for list and additional feature selection)
2959 @item -E @var{var}=@var{value}
2960 Set environment @var{var} to @var{value}.
2962 Remove @var{var} from the environment.
2964 Offset guest address by the specified number of bytes. This is useful when
2965 the address region required by guest applications is reserved on the host.
2966 This option is currently only supported on some hosts.
2968 Pre-allocate a guest virtual address space of the given size (in bytes).
2969 "G", "M", and "k" suffixes may be used when specifying the size.
2976 Activate logging of the specified items (use '-d help' for a list of log items)
2978 Act as if the host page size was 'pagesize' bytes
2980 Wait gdb connection to port
2982 Run the emulation in single step mode.
2985 Environment variables:
2989 Print system calls and arguments similar to the 'strace' program
2990 (NOTE: the actual 'strace' program will not work because the user
2991 space emulator hasn't implemented ptrace). At the moment this is
2992 incomplete. All system calls that don't have a specific argument
2993 format are printed with information for six arguments. Many
2994 flag-style arguments don't have decoders and will show up as numbers.
2997 @node Other binaries
2998 @subsection Other binaries
3000 @cindex user mode (Alpha)
3001 @command{qemu-alpha} TODO.
3003 @cindex user mode (ARM)
3004 @command{qemu-armeb} TODO.
3006 @cindex user mode (ARM)
3007 @command{qemu-arm} is also capable of running ARM "Angel" semihosted ELF
3008 binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
3009 configurations), and arm-uclinux bFLT format binaries.
3011 @cindex user mode (ColdFire)
3012 @cindex user mode (M68K)
3013 @command{qemu-m68k} is capable of running semihosted binaries using the BDM
3014 (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
3015 coldfire uClinux bFLT format binaries.
3017 The binary format is detected automatically.
3019 @cindex user mode (Cris)
3020 @command{qemu-cris} TODO.
3022 @cindex user mode (i386)
3023 @command{qemu-i386} TODO.
3024 @command{qemu-x86_64} TODO.
3026 @cindex user mode (Microblaze)
3027 @command{qemu-microblaze} TODO.
3029 @cindex user mode (MIPS)
3030 @command{qemu-mips} TODO.
3031 @command{qemu-mipsel} TODO.
3033 @cindex user mode (NiosII)
3034 @command{qemu-nios2} TODO.
3036 @cindex user mode (PowerPC)
3037 @command{qemu-ppc64abi32} TODO.
3038 @command{qemu-ppc64} TODO.
3039 @command{qemu-ppc} TODO.
3041 @cindex user mode (SH4)
3042 @command{qemu-sh4eb} TODO.
3043 @command{qemu-sh4} TODO.
3045 @cindex user mode (SPARC)
3046 @command{qemu-sparc} can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
3048 @command{qemu-sparc32plus} can execute Sparc32 and SPARC32PLUS binaries
3049 (Sparc64 CPU, 32 bit ABI).
3051 @command{qemu-sparc64} can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
3052 SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
3054 @node BSD User space emulator
3055 @section BSD User space emulator
3060 * BSD Command line options::
3064 @subsection BSD Status
3068 target Sparc64 on Sparc64: Some trivial programs work.
3071 @node BSD Quick Start
3072 @subsection Quick Start
3074 In order to launch a BSD process, QEMU needs the process executable
3075 itself and all the target dynamic libraries used by it.
3079 @item On Sparc64, you can just try to launch any process by using the native
3083 qemu-sparc64 /bin/ls
3088 @node BSD Command line options
3089 @subsection Command line options
3092 @command{qemu-sparc64} [@option{-h]} [@option{-d]} [@option{-L} @var{path}] [@option{-s} @var{size}] [@option{-bsd} @var{type}] @var{program} [@var{arguments}...]
3099 Set the library root path (default=/)
3101 Set the stack size in bytes (default=524288)
3102 @item -ignore-environment
3103 Start with an empty environment. Without this option,
3104 the initial environment is a copy of the caller's environment.
3105 @item -E @var{var}=@var{value}
3106 Set environment @var{var} to @var{value}.
3108 Remove @var{var} from the environment.
3110 Set the type of the emulated BSD Operating system. Valid values are
3111 FreeBSD, NetBSD and OpenBSD (default).
3118 Activate logging of the specified items (use '-d help' for a list of log items)
3120 Act as if the host page size was 'pagesize' bytes
3122 Run the emulation in single step mode.
3126 @include qemu-tech.texi
3131 QEMU is a trademark of Fabrice Bellard.
3133 QEMU is released under the
3134 @url{https://www.gnu.org/licenses/gpl-2.0.txt,GNU General Public License},
3135 version 2. Parts of QEMU have specific licenses, see file
3136 @url{http://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE,LICENSE}.
3150 @section Concept Index
3151 This is the main index. Should we combine all keywords in one index? TODO
3154 @node Function Index
3155 @section Function Index
3156 This index could be used for command line options and monitor functions.
3159 @node Keystroke Index
3160 @section Keystroke Index
3162 This is a list of all keystrokes which have a special function
3163 in system emulation.
3168 @section Program Index
3171 @node Data Type Index
3172 @section Data Type Index
3174 This index could be used for qdev device names and options.
3178 @node Variable Index
3179 @section Variable Index