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::
41 * Deprecated features::
42 * Supported build platforms::
54 * intro_features:: Features
60 QEMU is a FAST! processor emulator using dynamic translation to
61 achieve good emulation speed.
63 @cindex operating modes
64 QEMU has two operating modes:
67 @cindex system emulation
68 @item Full system emulation. In this mode, QEMU emulates a full system (for
69 example a PC), including one or several processors and various
70 peripherals. It can be used to launch different Operating Systems
71 without rebooting the PC or to debug system code.
73 @cindex user mode emulation
74 @item User mode emulation. In this mode, QEMU can launch
75 processes compiled for one CPU on another CPU. It can be used to
76 launch the Wine Windows API emulator (@url{https://www.winehq.org}) or
77 to ease cross-compilation and cross-debugging.
81 QEMU has the following features:
84 @item QEMU can run without a host kernel driver and yet gives acceptable
85 performance. It uses dynamic translation to native code for reasonable speed,
86 with support for self-modifying code and precise exceptions.
88 @item It is portable to several operating systems (GNU/Linux, *BSD, Mac OS X,
89 Windows) and architectures.
91 @item It performs accurate software emulation of the FPU.
94 QEMU user mode emulation has the following features:
96 @item Generic Linux system call converter, including most ioctls.
98 @item clone() emulation using native CPU clone() to use Linux scheduler for threads.
100 @item Accurate signal handling by remapping host signals to target signals.
103 QEMU full system emulation has the following features:
106 QEMU uses a full software MMU for maximum portability.
109 QEMU can optionally use an in-kernel accelerator, like kvm. The accelerators
110 execute most of the guest code natively, while
111 continuing to emulate the rest of the machine.
114 Various hardware devices can be emulated and in some cases, host
115 devices (e.g. serial and parallel ports, USB, drives) can be used
116 transparently by the guest Operating System. Host device passthrough
117 can be used for talking to external physical peripherals (e.g. a
118 webcam, modem or tape drive).
121 Symmetric multiprocessing (SMP) support. Currently, an in-kernel
122 accelerator is required to use more than one host CPU for emulation.
127 @node QEMU PC System emulator
128 @chapter QEMU PC System emulator
129 @cindex system emulation (PC)
132 * pcsys_introduction:: Introduction
133 * pcsys_quickstart:: Quick Start
134 * sec_invocation:: Invocation
135 * pcsys_keys:: Keys in the graphical frontends
136 * mux_keys:: Keys in the character backend multiplexer
137 * pcsys_monitor:: QEMU Monitor
138 * disk_images:: Disk Images
139 * pcsys_network:: Network emulation
140 * pcsys_other_devs:: Other Devices
141 * direct_linux_boot:: Direct Linux Boot
142 * pcsys_usb:: USB emulation
143 * vnc_security:: VNC security
144 * network_tls:: TLS setup for network services
145 * gdb_usage:: GDB usage
146 * pcsys_os_specific:: Target OS specific information
149 @node pcsys_introduction
150 @section Introduction
152 @c man begin DESCRIPTION
154 The QEMU PC System emulator simulates the
155 following peripherals:
159 i440FX host PCI bridge and PIIX3 PCI to ISA bridge
161 Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
162 extensions (hardware level, including all non standard modes).
164 PS/2 mouse and keyboard
166 2 PCI IDE interfaces with hard disk and CD-ROM support
170 PCI and ISA network adapters
174 IPMI BMC, either and internal or external one
176 Creative SoundBlaster 16 sound card
178 ENSONIQ AudioPCI ES1370 sound card
180 Intel 82801AA AC97 Audio compatible sound card
182 Intel HD Audio Controller and HDA codec
184 Adlib (OPL2) - Yamaha YM3812 compatible chip
186 Gravis Ultrasound GF1 sound card
188 CS4231A compatible sound card
190 PCI UHCI, OHCI, EHCI or XHCI USB controller and a virtual USB-1.1 hub.
193 SMP is supported with up to 255 CPUs.
195 QEMU uses the PC BIOS from the Seabios project and the Plex86/Bochs LGPL
198 QEMU uses YM3812 emulation by Tatsuyuki Satoh.
200 QEMU uses GUS emulation (GUSEMU32 @url{http://www.deinmeister.de/gusemu/})
201 by Tibor "TS" Schütz.
203 Note that, by default, GUS shares IRQ(7) with parallel ports and so
204 QEMU must be told to not have parallel ports to have working GUS.
207 qemu-system-i386 dos.img -soundhw gus -parallel none
212 qemu-system-i386 dos.img -device gus,irq=5
215 Or some other unclaimed IRQ.
217 CS4231A is the chip used in Windows Sound System and GUSMAX products
221 @node pcsys_quickstart
225 Download and uncompress the linux image (@file{linux.img}) and type:
228 qemu-system-i386 linux.img
231 Linux should boot and give you a prompt.
237 @c man begin SYNOPSIS
238 @command{qemu-system-i386} [@var{options}] [@var{disk_image}]
243 @var{disk_image} is a raw hard disk image for IDE hard disk 0. Some
244 targets do not need a disk image.
246 @include qemu-options.texi
250 @subsection Device URL Syntax
251 @c TODO merge this with section Disk Images
255 In addition to using normal file images for the emulated storage devices,
256 QEMU can also use networked resources such as iSCSI devices. These are
257 specified using a special URL syntax.
261 iSCSI support allows QEMU to access iSCSI resources directly and use as
262 images for the guest storage. Both disk and cdrom images are supported.
264 Syntax for specifying iSCSI LUNs is
265 ``iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>''
267 By default qemu will use the iSCSI initiator-name
268 'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command
269 line or a configuration file.
271 Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect
272 stalled requests and force a reestablishment of the session. The timeout
273 is specified in seconds. The default is 0 which means no timeout. Libiscsi
274 1.15.0 or greater is required for this feature.
276 Example (without authentication):
278 qemu-system-i386 -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \
279 -cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \
280 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
283 Example (CHAP username/password via URL):
285 qemu-system-i386 -drive file=iscsi://user%password@@192.0.2.1/iqn.2001-04.com.example/1
288 Example (CHAP username/password via environment variables):
290 LIBISCSI_CHAP_USERNAME="user" \
291 LIBISCSI_CHAP_PASSWORD="password" \
292 qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
296 QEMU supports NBD (Network Block Devices) both using TCP protocol as well
297 as Unix Domain Sockets.
299 Syntax for specifying a NBD device using TCP
300 ``nbd:<server-ip>:<port>[:exportname=<export>]''
302 Syntax for specifying a NBD device using Unix Domain Sockets
303 ``nbd:unix:<domain-socket>[:exportname=<export>]''
307 qemu-system-i386 --drive file=nbd:192.0.2.1:30000
310 Example for Unix Domain Sockets
312 qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket
316 QEMU supports SSH (Secure Shell) access to remote disks.
320 qemu-system-i386 -drive file=ssh://user@@host/path/to/disk.img
321 qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
324 Currently authentication must be done using ssh-agent. Other
325 authentication methods may be supported in future.
328 Sheepdog is a distributed storage system for QEMU.
329 QEMU supports using either local sheepdog devices or remote networked
332 Syntax for specifying a sheepdog device
334 sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]
339 qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
342 See also @url{https://sheepdog.github.io/sheepdog/}.
345 GlusterFS is a user space distributed file system.
346 QEMU supports the use of GlusterFS volumes for hosting VM disk images using
347 TCP, Unix Domain Sockets and RDMA transport protocols.
349 Syntax for specifying a VM disk image on GlusterFS volume is
353 gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...]
356 'json:@{"driver":"qcow2","file":@{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...",
357 @ "server":[@{"type":"tcp","host":"...","port":"..."@},
358 @ @{"type":"unix","socket":"..."@}]@}@}'
365 qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img,
366 @ file.debug=9,file.logfile=/var/log/qemu-gluster.log
369 qemu-system-x86_64 'json:@{"driver":"qcow2",
370 @ "file":@{"driver":"gluster",
371 @ "volume":"testvol","path":"a.img",
372 @ "debug":9,"logfile":"/var/log/qemu-gluster.log",
373 @ "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@},
374 @ @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}'
375 qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
376 @ file.debug=9,file.logfile=/var/log/qemu-gluster.log,
377 @ file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
378 @ file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
381 See also @url{http://www.gluster.org}.
383 @item HTTP/HTTPS/FTP/FTPS
384 QEMU supports read-only access to files accessed over http(s) and ftp(s).
386 Syntax using a single filename:
388 <protocol>://[<username>[:<password>]@@]<host>/<path>
394 'http', 'https', 'ftp', or 'ftps'.
397 Optional username for authentication to the remote server.
400 Optional password for authentication to the remote server.
403 Address of the remote server.
406 Path on the remote server, including any query string.
409 The following options are also supported:
412 The full URL when passing options to the driver explicitly.
415 The amount of data to read ahead with each range request to the remote server.
416 This value may optionally have the suffix 'T', 'G', 'M', 'K', 'k' or 'b'. If it
417 does not have a suffix, it will be assumed to be in bytes. The value must be a
418 multiple of 512 bytes. It defaults to 256k.
421 Whether to verify the remote server's certificate when connecting over SSL. It
422 can have the value 'on' or 'off'. It defaults to 'on'.
425 Send this cookie (it can also be a list of cookies separated by ';') with
426 each outgoing request. Only supported when using protocols such as HTTP
427 which support cookies, otherwise ignored.
430 Set the timeout in seconds of the CURL connection. This timeout is the time
431 that CURL waits for a response from the remote server to get the size of the
432 image to be downloaded. If not set, the default timeout of 5 seconds is used.
435 Note that when passing options to qemu explicitly, @option{driver} is the value
438 Example: boot from a remote Fedora 20 live ISO image
440 qemu-system-x86_64 --drive media=cdrom,file=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
442 qemu-system-x86_64 --drive media=cdrom,file.driver=http,file.url=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
445 Example: boot from a remote Fedora 20 cloud image using a local overlay for
446 writes, copy-on-read, and a readahead of 64k
448 qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"http",, "file.url":"https://dl.fedoraproject.org/pub/fedora/linux/releases/20/Images/x86_64/Fedora-x86_64-20-20131211.1-sda.qcow2",, "file.readahead":"64k"@}' /tmp/Fedora-x86_64-20-20131211.1-sda.qcow2
450 qemu-system-x86_64 -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on
453 Example: boot from an image stored on a VMware vSphere server with a self-signed
454 certificate using a local overlay for writes, a readahead of 64k and a timeout
457 qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"https",, "file.url":"https://user:password@@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k",, "file.timeout":10@}' /tmp/test.qcow2
459 qemu-system-x86_64 -drive file=/tmp/test.qcow2
467 @section Keys in the graphical frontends
471 During the graphical emulation, you can use special key combinations to change
472 modes. The default key mappings are shown below, but if you use @code{-alt-grab}
473 then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt) and if you use
474 @code{-ctrl-grab} then the modifier is the right Ctrl key (instead of Ctrl-Alt):
491 Restore the screen's un-scaled dimensions
495 Switch to virtual console 'n'. Standard console mappings are:
498 Target system display
507 Toggle mouse and keyboard grab.
513 @kindex Ctrl-PageDown
514 In the virtual consoles, you can use @key{Ctrl-Up}, @key{Ctrl-Down},
515 @key{Ctrl-PageUp} and @key{Ctrl-PageDown} to move in the back log.
520 @section Keys in the character backend multiplexer
524 During emulation, if you are using a character backend multiplexer
525 (which is the default if you are using @option{-nographic}) then
526 several commands are available via an escape sequence. These
527 key sequences all start with an escape character, which is @key{Ctrl-a}
528 by default, but can be changed with @option{-echr}. The list below assumes
529 you're using the default.
540 Save disk data back to file (if -snapshot)
543 Toggle console timestamps
546 Send break (magic sysrq in Linux)
549 Rotate between the frontends connected to the multiplexer (usually
550 this switches between the monitor and the console)
552 @kindex Ctrl-a Ctrl-a
553 Send the escape character to the frontend
560 The HTML documentation of QEMU for more precise information and Linux
561 user mode emulator invocation.
571 @section QEMU Monitor
574 The QEMU monitor is used to give complex commands to the QEMU
575 emulator. You can use it to:
580 Remove or insert removable media images
581 (such as CD-ROM or floppies).
584 Freeze/unfreeze the Virtual Machine (VM) and save or restore its state
587 @item Inspect the VM state without an external debugger.
593 The following commands are available:
595 @include qemu-monitor.texi
597 @include qemu-monitor-info.texi
599 @subsection Integer expressions
601 The monitor understands integers expressions for every integer
602 argument. You can use register names to get the value of specifics
603 CPU registers by prefixing them with @emph{$}.
608 QEMU supports many disk image formats, including growable disk images
609 (their size increase as non empty sectors are written), compressed and
610 encrypted disk images.
613 * disk_images_quickstart:: Quick start for disk image creation
614 * disk_images_snapshot_mode:: Snapshot mode
615 * vm_snapshots:: VM snapshots
616 * qemu_img_invocation:: qemu-img Invocation
617 * qemu_nbd_invocation:: qemu-nbd Invocation
618 * disk_images_formats:: Disk image file formats
619 * host_drives:: Using host drives
620 * disk_images_fat_images:: Virtual FAT disk images
621 * disk_images_nbd:: NBD access
622 * disk_images_sheepdog:: Sheepdog disk images
623 * disk_images_iscsi:: iSCSI LUNs
624 * disk_images_gluster:: GlusterFS disk images
625 * disk_images_ssh:: Secure Shell (ssh) disk images
626 * disk_images_nvme:: NVMe userspace driver
627 * disk_image_locking:: Disk image file locking
630 @node disk_images_quickstart
631 @subsection Quick start for disk image creation
633 You can create a disk image with the command:
635 qemu-img create myimage.img mysize
637 where @var{myimage.img} is the disk image filename and @var{mysize} is its
638 size in kilobytes. You can add an @code{M} suffix to give the size in
639 megabytes and a @code{G} suffix for gigabytes.
641 See @ref{qemu_img_invocation} for more information.
643 @node disk_images_snapshot_mode
644 @subsection Snapshot mode
646 If you use the option @option{-snapshot}, all disk images are
647 considered as read only. When sectors in written, they are written in
648 a temporary file created in @file{/tmp}. You can however force the
649 write back to the raw disk images by using the @code{commit} monitor
650 command (or @key{C-a s} in the serial console).
653 @subsection VM snapshots
655 VM snapshots are snapshots of the complete virtual machine including
656 CPU state, RAM, device state and the content of all the writable
657 disks. In order to use VM snapshots, you must have at least one non
658 removable and writable block device using the @code{qcow2} disk image
659 format. Normally this device is the first virtual hard drive.
661 Use the monitor command @code{savevm} to create a new VM snapshot or
662 replace an existing one. A human readable name can be assigned to each
663 snapshot in addition to its numerical ID.
665 Use @code{loadvm} to restore a VM snapshot and @code{delvm} to remove
666 a VM snapshot. @code{info snapshots} lists the available snapshots
667 with their associated information:
670 (qemu) info snapshots
671 Snapshot devices: hda
672 Snapshot list (from hda):
673 ID TAG VM SIZE DATE VM CLOCK
674 1 start 41M 2006-08-06 12:38:02 00:00:14.954
675 2 40M 2006-08-06 12:43:29 00:00:18.633
676 3 msys 40M 2006-08-06 12:44:04 00:00:23.514
679 A VM snapshot is made of a VM state info (its size is shown in
680 @code{info snapshots}) and a snapshot of every writable disk image.
681 The VM state info is stored in the first @code{qcow2} non removable
682 and writable block device. The disk image snapshots are stored in
683 every disk image. The size of a snapshot in a disk image is difficult
684 to evaluate and is not shown by @code{info snapshots} because the
685 associated disk sectors are shared among all the snapshots to save
686 disk space (otherwise each snapshot would need a full copy of all the
689 When using the (unrelated) @code{-snapshot} option
690 (@ref{disk_images_snapshot_mode}), you can always make VM snapshots,
691 but they are deleted as soon as you exit QEMU.
693 VM snapshots currently have the following known limitations:
696 They cannot cope with removable devices if they are removed or
697 inserted after a snapshot is done.
699 A few device drivers still have incomplete snapshot support so their
700 state is not saved or restored properly (in particular USB).
703 @node qemu_img_invocation
704 @subsection @code{qemu-img} Invocation
706 @include qemu-img.texi
708 @node qemu_nbd_invocation
709 @subsection @code{qemu-nbd} Invocation
711 @include qemu-nbd.texi
713 @include docs/qemu-block-drivers.texi
716 @section Network emulation
718 QEMU can simulate several network cards (PCI or ISA cards on the PC
719 target) and can connect them to an arbitrary number of Virtual Local
720 Area Networks (VLANs). Host TAP devices can be connected to any QEMU
721 VLAN. VLAN can be connected between separate instances of QEMU to
722 simulate large networks. For simpler usage, a non privileged user mode
723 network stack can replace the TAP device to have a basic network
728 QEMU simulates several VLANs. A VLAN can be symbolised as a virtual
729 connection between several network devices. These devices can be for
730 example QEMU virtual Ethernet cards or virtual Host ethernet devices
733 @subsection Using TAP network interfaces
735 This is the standard way to connect QEMU to a real network. QEMU adds
736 a virtual network device on your host (called @code{tapN}), and you
737 can then configure it as if it was a real ethernet card.
739 @subsubsection Linux host
741 As an example, you can download the @file{linux-test-xxx.tar.gz}
742 archive and copy the script @file{qemu-ifup} in @file{/etc} and
743 configure properly @code{sudo} so that the command @code{ifconfig}
744 contained in @file{qemu-ifup} can be executed as root. You must verify
745 that your host kernel supports the TAP network interfaces: the
746 device @file{/dev/net/tun} must be present.
748 See @ref{sec_invocation} to have examples of command lines using the
749 TAP network interfaces.
751 @subsubsection Windows host
753 There is a virtual ethernet driver for Windows 2000/XP systems, called
754 TAP-Win32. But it is not included in standard QEMU for Windows,
755 so you will need to get it separately. It is part of OpenVPN package,
756 so download OpenVPN from : @url{https://openvpn.net/}.
758 @subsection Using the user mode network stack
760 By using the option @option{-net user} (default configuration if no
761 @option{-net} option is specified), QEMU uses a completely user mode
762 network stack (you don't need root privilege to use the virtual
763 network). The virtual network configuration is the following:
767 QEMU VLAN <------> Firewall/DHCP server <-----> Internet
770 ----> DNS server (10.0.2.3)
772 ----> SMB server (10.0.2.4)
775 The QEMU VM behaves as if it was behind a firewall which blocks all
776 incoming connections. You can use a DHCP client to automatically
777 configure the network in the QEMU VM. The DHCP server assign addresses
778 to the hosts starting from 10.0.2.15.
780 In order to check that the user mode network is working, you can ping
781 the address 10.0.2.2 and verify that you got an address in the range
782 10.0.2.x from the QEMU virtual DHCP server.
784 Note that ICMP traffic in general does not work with user mode networking.
785 @code{ping}, aka. ICMP echo, to the local router (10.0.2.2) shall work,
786 however. If you're using QEMU on Linux >= 3.0, it can use unprivileged ICMP
787 ping sockets to allow @code{ping} to the Internet. The host admin has to set
788 the ping_group_range in order to grant access to those sockets. To allow ping
789 for GID 100 (usually users group):
792 echo 100 100 > /proc/sys/net/ipv4/ping_group_range
795 When using the built-in TFTP server, the router is also the TFTP
798 When using the @option{'-netdev user,hostfwd=...'} option, TCP or UDP
799 connections can be redirected from the host to the guest. It allows for
800 example to redirect X11, telnet or SSH connections.
802 @subsection Connecting VLANs between QEMU instances
804 Using the @option{-net socket} option, it is possible to make VLANs
805 that span several QEMU instances. See @ref{sec_invocation} to have a
808 @node pcsys_other_devs
809 @section Other Devices
811 @subsection Inter-VM Shared Memory device
813 On Linux hosts, a shared memory device is available. The basic syntax
817 qemu-system-x86_64 -device ivshmem-plain,memdev=@var{hostmem}
820 where @var{hostmem} names a host memory backend. For a POSIX shared
821 memory backend, use something like
824 -object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=@var{hostmem}
827 If desired, interrupts can be sent between guest VMs accessing the same shared
828 memory region. Interrupt support requires using a shared memory server and
829 using a chardev socket to connect to it. The code for the shared memory server
830 is qemu.git/contrib/ivshmem-server. An example syntax when using the shared
834 # First start the ivshmem server once and for all
835 ivshmem-server -p @var{pidfile} -S @var{path} -m @var{shm-name} -l @var{shm-size} -n @var{vectors}
837 # Then start your qemu instances with matching arguments
838 qemu-system-x86_64 -device ivshmem-doorbell,vectors=@var{vectors},chardev=@var{id}
839 -chardev socket,path=@var{path},id=@var{id}
842 When using the server, the guest will be assigned a VM ID (>=0) that allows guests
843 using the same server to communicate via interrupts. Guests can read their
844 VM ID from a device register (see ivshmem-spec.txt).
846 @subsubsection Migration with ivshmem
848 With device property @option{master=on}, the guest will copy the shared
849 memory on migration to the destination host. With @option{master=off},
850 the guest will not be able to migrate with the device attached. In the
851 latter case, the device should be detached and then reattached after
852 migration using the PCI hotplug support.
854 At most one of the devices sharing the same memory can be master. The
855 master must complete migration before you plug back the other devices.
857 @subsubsection ivshmem and hugepages
859 Instead of specifying the <shm size> using POSIX shm, you may specify
860 a memory backend that has hugepage support:
863 qemu-system-x86_64 -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,id=mb1
864 -device ivshmem-plain,memdev=mb1
867 ivshmem-server also supports hugepages mount points with the
868 @option{-m} memory path argument.
870 @node direct_linux_boot
871 @section Direct Linux Boot
873 This section explains how to launch a Linux kernel inside QEMU without
874 having to make a full bootable image. It is very useful for fast Linux
879 qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"
882 Use @option{-kernel} to provide the Linux kernel image and
883 @option{-append} to give the kernel command line arguments. The
884 @option{-initrd} option can be used to provide an INITRD image.
886 When using the direct Linux boot, a disk image for the first hard disk
887 @file{hda} is required because its boot sector is used to launch the
890 If you do not need graphical output, you can disable it and redirect
891 the virtual serial port and the QEMU monitor to the console with the
892 @option{-nographic} option. The typical command line is:
894 qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
895 -append "root=/dev/hda console=ttyS0" -nographic
898 Use @key{Ctrl-a c} to switch between the serial console and the
899 monitor (@pxref{pcsys_keys}).
902 @section USB emulation
904 QEMU can emulate a PCI UHCI, OHCI, EHCI or XHCI USB controller. You can
905 plug virtual USB devices or real host USB devices (only works with certain
906 host operating systems). QEMU will automatically create and connect virtual
907 USB hubs as necessary to connect multiple USB devices.
914 @subsection Connecting USB devices
916 USB devices can be connected with the @option{-device usb-...} command line
917 option or the @code{device_add} monitor command. Available devices are:
921 Virtual Mouse. This will override the PS/2 mouse emulation when activated.
923 Pointer device that uses absolute coordinates (like a touchscreen).
924 This means QEMU is able to report the mouse position without having
925 to grab the mouse. Also overrides the PS/2 mouse emulation when activated.
926 @item usb-storage,drive=@var{drive_id}
927 Mass storage device backed by @var{drive_id} (@pxref{disk_images})
929 USB attached SCSI device, see
930 @url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
933 Bulk-only transport storage device, see
934 @url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
935 for details here, too
936 @item usb-mtp,x-root=@var{dir}
937 Media transfer protocol device, using @var{dir} as root of the file tree
938 that is presented to the guest.
939 @item usb-host,hostbus=@var{bus},hostaddr=@var{addr}
940 Pass through the host device identified by @var{bus} and @var{addr}
941 @item usb-host,vendorid=@var{vendor},productid=@var{product}
942 Pass through the host device identified by @var{vendor} and @var{product} ID
943 @item usb-wacom-tablet
944 Virtual Wacom PenPartner tablet. This device is similar to the @code{tablet}
945 above but it can be used with the tslib library because in addition to touch
946 coordinates it reports touch pressure.
948 Standard USB keyboard. Will override the PS/2 keyboard (if present).
949 @item usb-serial,chardev=@var{id}
950 Serial converter. This emulates an FTDI FT232BM chip connected to host character
952 @item usb-braille,chardev=@var{id}
953 Braille device. This will use BrlAPI to display the braille output on a real
954 or fake device referenced by @var{id}.
955 @item usb-net[,netdev=@var{id}]
956 Network adapter that supports CDC ethernet and RNDIS protocols. @var{id}
957 specifies a netdev defined with @code{-netdev @dots{},id=@var{id}}.
958 For instance, user-mode networking can be used with
960 qemu-system-i386 [...] -netdev user,id=net0 -device usb-net,netdev=net0
963 Smartcard reader device
967 Bluetooth dongle for the transport layer of HCI. It is connected to HCI
968 scatternet 0 by default (corresponds to @code{-bt hci,vlan=0}).
969 Note that the syntax for the @code{-device usb-bt-dongle} option is not as
970 useful yet as it was with the legacy @code{-usbdevice} option. So to
971 configure an USB bluetooth device, you might need to use
972 "@code{-usbdevice bt}[:@var{hci-type}]" instead. This configures a
973 bluetooth dongle whose type is specified in the same format as with
974 the @option{-bt hci} option, @pxref{bt-hcis,,allowed HCI types}. If
975 no type is given, the HCI logic corresponds to @code{-bt hci,vlan=0}.
976 This USB device implements the USB Transport Layer of HCI. Example
979 @command{qemu-system-i386} [...@var{OPTIONS}...] @option{-usbdevice} bt:hci,vlan=3 @option{-bt} device:keyboard,vlan=3
983 @node host_usb_devices
984 @subsection Using host USB devices on a Linux host
986 WARNING: this is an experimental feature. QEMU will slow down when
987 using it. USB devices requiring real time streaming (i.e. USB Video
988 Cameras) are not supported yet.
991 @item If you use an early Linux 2.4 kernel, verify that no Linux driver
992 is actually using the USB device. A simple way to do that is simply to
993 disable the corresponding kernel module by renaming it from @file{mydriver.o}
994 to @file{mydriver.o.disabled}.
996 @item Verify that @file{/proc/bus/usb} is working (most Linux distributions should enable it by default). You should see something like that:
1002 @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:
1004 chown -R myuid /proc/bus/usb
1007 @item Launch QEMU and do in the monitor:
1010 Device 1.2, speed 480 Mb/s
1011 Class 00: USB device 1234:5678, USB DISK
1013 You should see the list of the devices you can use (Never try to use
1014 hubs, it won't work).
1016 @item Add the device in QEMU by using:
1018 device_add usb-host,vendorid=0x1234,productid=0x5678
1021 Normally the guest OS should report that a new USB device is plugged.
1022 You can use the option @option{-device usb-host,...} to do the same.
1024 @item Now you can try to use the host USB device in QEMU.
1028 When relaunching QEMU, you may have to unplug and plug again the USB
1029 device to make it work again (this is a bug).
1032 @section VNC security
1034 The VNC server capability provides access to the graphical console
1035 of the guest VM across the network. This has a number of security
1036 considerations depending on the deployment scenarios.
1040 * vnc_sec_password::
1041 * vnc_sec_certificate::
1042 * vnc_sec_certificate_verify::
1043 * vnc_sec_certificate_pw::
1045 * vnc_sec_certificate_sasl::
1049 @subsection Without passwords
1051 The simplest VNC server setup does not include any form of authentication.
1052 For this setup it is recommended to restrict it to listen on a UNIX domain
1053 socket only. For example
1056 qemu-system-i386 [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc
1059 This ensures that only users on local box with read/write access to that
1060 path can access the VNC server. To securely access the VNC server from a
1061 remote machine, a combination of netcat+ssh can be used to provide a secure
1064 @node vnc_sec_password
1065 @subsection With passwords
1067 The VNC protocol has limited support for password based authentication. Since
1068 the protocol limits passwords to 8 characters it should not be considered
1069 to provide high security. The password can be fairly easily brute-forced by
1070 a client making repeat connections. For this reason, a VNC server using password
1071 authentication should be restricted to only listen on the loopback interface
1072 or UNIX domain sockets. Password authentication is not supported when operating
1073 in FIPS 140-2 compliance mode as it requires the use of the DES cipher. Password
1074 authentication is requested with the @code{password} option, and then once QEMU
1075 is running the password is set with the monitor. Until the monitor is used to
1076 set the password all clients will be rejected.
1079 qemu-system-i386 [...OPTIONS...] -vnc :1,password -monitor stdio
1080 (qemu) change vnc password
1085 @node vnc_sec_certificate
1086 @subsection With x509 certificates
1088 The QEMU VNC server also implements the VeNCrypt extension allowing use of
1089 TLS for encryption of the session, and x509 certificates for authentication.
1090 The use of x509 certificates is strongly recommended, because TLS on its
1091 own is susceptible to man-in-the-middle attacks. Basic x509 certificate
1092 support provides a secure session, but no authentication. This allows any
1093 client to connect, and provides an encrypted session.
1096 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509=/etc/pki/qemu -monitor stdio
1099 In the above example @code{/etc/pki/qemu} should contain at least three files,
1100 @code{ca-cert.pem}, @code{server-cert.pem} and @code{server-key.pem}. Unprivileged
1101 users will want to use a private directory, for example @code{$HOME/.pki/qemu}.
1102 NB the @code{server-key.pem} file should be protected with file mode 0600 to
1103 only be readable by the user owning it.
1105 @node vnc_sec_certificate_verify
1106 @subsection With x509 certificates and client verification
1108 Certificates can also provide a means to authenticate the client connecting.
1109 The server will request that the client provide a certificate, which it will
1110 then validate against the CA certificate. This is a good choice if deploying
1111 in an environment with a private internal certificate authority.
1114 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509verify=/etc/pki/qemu -monitor stdio
1118 @node vnc_sec_certificate_pw
1119 @subsection With x509 certificates, client verification and passwords
1121 Finally, the previous method can be combined with VNC password authentication
1122 to provide two layers of authentication for clients.
1125 qemu-system-i386 [...OPTIONS...] -vnc :1,password,tls,x509verify=/etc/pki/qemu -monitor stdio
1126 (qemu) change vnc password
1133 @subsection With SASL authentication
1135 The SASL authentication method is a VNC extension, that provides an
1136 easily extendable, pluggable authentication method. This allows for
1137 integration with a wide range of authentication mechanisms, such as
1138 PAM, GSSAPI/Kerberos, LDAP, SQL databases, one-time keys and more.
1139 The strength of the authentication depends on the exact mechanism
1140 configured. If the chosen mechanism also provides a SSF layer, then
1141 it will encrypt the datastream as well.
1143 Refer to the later docs on how to choose the exact SASL mechanism
1144 used for authentication, but assuming use of one supporting SSF,
1145 then QEMU can be launched with:
1148 qemu-system-i386 [...OPTIONS...] -vnc :1,sasl -monitor stdio
1151 @node vnc_sec_certificate_sasl
1152 @subsection With x509 certificates and SASL authentication
1154 If the desired SASL authentication mechanism does not supported
1155 SSF layers, then it is strongly advised to run it in combination
1156 with TLS and x509 certificates. This provides securely encrypted
1157 data stream, avoiding risk of compromising of the security
1158 credentials. This can be enabled, by combining the 'sasl' option
1159 with the aforementioned TLS + x509 options:
1162 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509,sasl -monitor stdio
1165 @node vnc_setup_sasl
1167 @subsection Configuring SASL mechanisms
1169 The following documentation assumes use of the Cyrus SASL implementation on a
1170 Linux host, but the principles should apply to any other SASL implementation
1171 or host. When SASL is enabled, the mechanism configuration will be loaded from
1172 system default SASL service config /etc/sasl2/qemu.conf. If running QEMU as an
1173 unprivileged user, an environment variable SASL_CONF_PATH can be used to make
1174 it search alternate locations for the service config file.
1176 If the TLS option is enabled for VNC, then it will provide session encryption,
1177 otherwise the SASL mechanism will have to provide encryption. In the latter
1178 case the list of possible plugins that can be used is drastically reduced. In
1179 fact only the GSSAPI SASL mechanism provides an acceptable level of security
1180 by modern standards. Previous versions of QEMU referred to the DIGEST-MD5
1181 mechanism, however, it has multiple serious flaws described in detail in
1182 RFC 6331 and thus should never be used any more. The SCRAM-SHA-1 mechanism
1183 provides a simple username/password auth facility similar to DIGEST-MD5, but
1184 does not support session encryption, so can only be used in combination with
1187 When not using TLS the recommended configuration is
1191 keytab: /etc/qemu/krb5.tab
1194 This says to use the 'GSSAPI' mechanism with the Kerberos v5 protocol, with
1195 the server principal stored in /etc/qemu/krb5.tab. For this to work the
1196 administrator of your KDC must generate a Kerberos principal for the server,
1197 with a name of 'qemu/somehost.example.com@@EXAMPLE.COM' replacing
1198 'somehost.example.com' with the fully qualified host name of the machine
1199 running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm.
1201 When using TLS, if username+password authentication is desired, then a
1202 reasonable configuration is
1205 mech_list: scram-sha-1
1206 sasldb_path: /etc/qemu/passwd.db
1209 The @code{saslpasswd2} program can be used to populate the @code{passwd.db}
1212 Other SASL configurations will be left as an exercise for the reader. Note that
1213 all mechanisms, except GSSAPI, should be combined with use of TLS to ensure a
1214 secure data channel.
1218 @section TLS setup for network services
1220 Almost all network services in QEMU have the ability to use TLS for
1221 session data encryption, along with x509 certificates for simple
1222 client authentication. What follows is a description of how to
1223 generate certificates suitable for usage with QEMU, and applies to
1224 the VNC server, character devices with the TCP backend, NBD server
1225 and client, and migration server and client.
1227 At a high level, QEMU requires certificates and private keys to be
1228 provided in PEM format. Aside from the core fields, the certificates
1229 should include various extension data sets, including v3 basic
1230 constraints data, key purpose, key usage and subject alt name.
1232 The GnuTLS package includes a command called @code{certtool} which can
1233 be used to easily generate certificates and keys in the required format
1234 with expected data present. Alternatively a certificate management
1235 service may be used.
1237 At a minimum it is necessary to setup a certificate authority, and
1238 issue certificates to each server. If using x509 certificates for
1239 authentication, then each client will also need to be issued a
1242 Assuming that the QEMU network services will only ever be exposed to
1243 clients on a private intranet, there is no need to use a commercial
1244 certificate authority to create certificates. A self-signed CA is
1245 sufficient, and in fact likely to be more secure since it removes
1246 the ability of malicious 3rd parties to trick the CA into mis-issuing
1247 certs for impersonating your services. The only likely exception
1248 where a commercial CA might be desirable is if enabling the VNC
1249 websockets server and exposing it directly to remote browser clients.
1250 In such a case it might be useful to use a commercial CA to avoid
1251 needing to install custom CA certs in the web browsers.
1253 The recommendation is for the server to keep its certificates in either
1254 @code{/etc/pki/qemu} or for unprivileged users in @code{$HOME/.pki/qemu}.
1258 * tls_generate_server::
1259 * tls_generate_client::
1262 @node tls_generate_ca
1263 @subsection Setup the Certificate Authority
1265 This step only needs to be performed once per organization / organizational
1266 unit. First the CA needs a private key. This key must be kept VERY secret
1267 and secure. If this key is compromised the entire trust chain of the certificates
1268 issued with it is lost.
1271 # certtool --generate-privkey > ca-key.pem
1274 To generate a self-signed certificate requires one core piece of information,
1275 the name of the organization. A template file @code{ca.info} should be
1276 populated with the desired data to avoid having to deal with interactive
1277 prompts from certtool:
1279 # cat > ca.info <<EOF
1280 cn = Name of your organization
1284 # certtool --generate-self-signed \
1285 --load-privkey ca-key.pem
1286 --template ca.info \
1287 --outfile ca-cert.pem
1290 The @code{ca} keyword in the template sets the v3 basic constraints extension
1291 to indicate this certificate is for a CA, while @code{cert_signing_key} sets
1292 the key usage extension to indicate this will be used for signing other keys.
1293 The generated @code{ca-cert.pem} file should be copied to all servers and
1294 clients wishing to utilize TLS support in the VNC server. The @code{ca-key.pem}
1295 must not be disclosed/copied anywhere except the host responsible for issuing
1298 @node tls_generate_server
1299 @subsection Issuing server certificates
1301 Each server (or host) needs to be issued with a key and certificate. When connecting
1302 the certificate is sent to the client which validates it against the CA certificate.
1303 The core pieces of information for a server certificate are the hostnames and/or IP
1304 addresses that will be used by clients when connecting. The hostname / IP address
1305 that the client specifies when connecting will be validated against the hostname(s)
1306 and IP address(es) recorded in the server certificate, and if no match is found
1307 the client will close the connection.
1309 Thus it is recommended that the server certificate include both the fully qualified
1310 and unqualified hostnames. If the server will have permanently assigned IP address(es),
1311 and clients are likely to use them when connecting, they may also be included in the
1312 certificate. Both IPv4 and IPv6 addresses are supported. Historically certificates
1313 only included 1 hostname in the @code{CN} field, however, usage of this field for
1314 validation is now deprecated. Instead modern TLS clients will validate against the
1315 Subject Alt Name extension data, which allows for multiple entries. In the future
1316 usage of the @code{CN} field may be discontinued entirely, so providing SAN
1317 extension data is strongly recommended.
1319 On the host holding the CA, create template files containing the information
1320 for each server, and use it to issue server certificates.
1323 # cat > server-hostNNN.info <<EOF
1324 organization = Name of your organization
1325 cn = hostNNN.foo.example.com
1327 dns_name = hostNNN.foo.example.com
1328 ip_address = 10.0.1.87
1329 ip_address = 192.8.0.92
1330 ip_address = 2620:0:cafe::87
1331 ip_address = 2001:24::92
1336 # certtool --generate-privkey > server-hostNNN-key.pem
1337 # certtool --generate-certificate \
1338 --load-ca-certificate ca-cert.pem \
1339 --load-ca-privkey ca-key.pem \
1340 --load-privkey server-hostNNN-key.pem \
1341 --template server-hostNNN.info \
1342 --outfile server-hostNNN-cert.pem
1345 The @code{dns_name} and @code{ip_address} fields in the template are setting
1346 the subject alt name extension data. The @code{tls_www_server} keyword is the
1347 key purpose extension to indicate this certificate is intended for usage in
1348 a web server. Although QEMU network services are not in fact HTTP servers
1349 (except for VNC websockets), setting this key purpose is still recommended.
1350 The @code{encryption_key} and @code{signing_key} keyword is the key usage
1351 extension to indicate this certificate is intended for usage in the data
1354 The @code{server-hostNNN-key.pem} and @code{server-hostNNN-cert.pem} files
1355 should now be securely copied to the server for which they were generated,
1356 and renamed to @code{server-key.pem} and @code{server-cert.pem} when added
1357 to the @code{/etc/pki/qemu} directory on the target host. The @code{server-key.pem}
1358 file is security sensitive and should be kept protected with file mode 0600
1359 to prevent disclosure.
1361 @node tls_generate_client
1362 @subsection Issuing client certificates
1364 The QEMU x509 TLS credential setup defaults to enabling client verification
1365 using certificates, providing a simple authentication mechanism. If this
1366 default is used, each client also needs to be issued a certificate. The client
1367 certificate contains enough metadata to uniquely identify the client with the
1368 scope of the certificate authority. The client certificate would typically
1369 include fields for organization, state, city, building, etc.
1371 Once again on the host holding the CA, create template files containing the
1372 information for each client, and use it to issue client certificates.
1376 # cat > client-hostNNN.info <<EOF
1379 locality = City Of London
1380 organization = Name of your organization
1381 cn = hostNNN.foo.example.com
1386 # certtool --generate-privkey > client-hostNNN-key.pem
1387 # certtool --generate-certificate \
1388 --load-ca-certificate ca-cert.pem \
1389 --load-ca-privkey ca-key.pem \
1390 --load-privkey client-hostNNN-key.pem \
1391 --template client-hostNNN.info \
1392 --outfile client-hostNNN-cert.pem
1395 The subject alt name extension data is not required for clients, so the
1396 the @code{dns_name} and @code{ip_address} fields are not included.
1397 The @code{tls_www_client} keyword is the key purpose extension to indicate
1398 this certificate is intended for usage in a web client. Although QEMU
1399 network clients are not in fact HTTP clients, setting this key purpose is
1400 still recommended. The @code{encryption_key} and @code{signing_key} keyword
1401 is the key usage extension to indicate this certificate is intended for
1402 usage in the data session.
1404 The @code{client-hostNNN-key.pem} and @code{client-hostNNN-cert.pem} files
1405 should now be securely copied to the client for which they were generated,
1406 and renamed to @code{client-key.pem} and @code{client-cert.pem} when added
1407 to the @code{/etc/pki/qemu} directory on the target host. The @code{client-key.pem}
1408 file is security sensitive and should be kept protected with file mode 0600
1409 to prevent disclosure.
1411 If a single host is going to be using TLS in both a client and server
1412 role, it is possible to create a single certificate to cover both roles.
1413 This would be quite common for the migration and NBD services, where a
1414 QEMU process will be started by accepting a TLS protected incoming migration,
1415 and later itself be migrated out to another host. To generate a single
1416 certificate, simply include the template data from both the client and server
1417 instructions in one.
1420 # cat > both-hostNNN.info <<EOF
1423 locality = City Of London
1424 organization = Name of your organization
1425 cn = hostNNN.foo.example.com
1427 dns_name = hostNNN.foo.example.com
1428 ip_address = 10.0.1.87
1429 ip_address = 192.8.0.92
1430 ip_address = 2620:0:cafe::87
1431 ip_address = 2001:24::92
1437 # certtool --generate-privkey > both-hostNNN-key.pem
1438 # certtool --generate-certificate \
1439 --load-ca-certificate ca-cert.pem \
1440 --load-ca-privkey ca-key.pem \
1441 --load-privkey both-hostNNN-key.pem \
1442 --template both-hostNNN.info \
1443 --outfile both-hostNNN-cert.pem
1446 When copying the PEM files to the target host, save them twice,
1447 once as @code{server-cert.pem} and @code{server-key.pem}, and
1448 again as @code{client-cert.pem} and @code{client-key.pem}.
1450 @node tls_creds_setup
1451 @subsection TLS x509 credential configuration
1453 QEMU has a standard mechanism for loading x509 credentials that will be
1454 used for network services and clients. It requires specifying the
1455 @code{tls-creds-x509} class name to the @code{--object} command line
1456 argument for the system emulators. Each set of credentials loaded should
1457 be given a unique string identifier via the @code{id} parameter. A single
1458 set of TLS credentials can be used for multiple network backends, so VNC,
1459 migration, NBD, character devices can all share the same credentials. Note,
1460 however, that credentials for use in a client endpoint must be loaded
1461 separately from those used in a server endpoint.
1463 When specifying the object, the @code{dir} parameters specifies which
1464 directory contains the credential files. This directory is expected to
1465 contain files with the names mentioned previously, @code{ca-cert.pem},
1466 @code{server-key.pem}, @code{server-cert.pem}, @code{client-key.pem}
1467 and @code{client-cert.pem} as appropriate. It is also possible to
1468 include a set of pre-generated Diffie-Hellman (DH) parameters in a file
1469 @code{dh-params.pem}, which can be created using the
1470 @code{certtool --generate-dh-params} command. If omitted, QEMU will
1471 dynamically generate DH parameters when loading the credentials.
1473 The @code{endpoint} parameter indicates whether the credentials will
1474 be used for a network client or server, and determines which PEM
1477 The @code{verify} parameter determines whether x509 certificate
1478 validation should be performed. This defaults to enabled, meaning
1479 clients will always validate the server hostname against the
1480 certificate subject alt name fields and/or CN field. It also
1481 means that servers will request that clients provide a certificate
1482 and validate them. Verification should never be turned off for
1483 client endpoints, however, it may be turned off for server endpoints
1484 if an alternative mechanism is used to authenticate clients. For
1485 example, the VNC server can use SASL to authenticate clients
1488 To load server credentials with client certificate validation
1492 $QEMU -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server
1495 while to load client credentials use
1498 $QEMU -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=client
1501 Network services which support TLS will all have a @code{tls-creds}
1502 parameter which expects the ID of the TLS credentials object. For
1506 $QEMU -vnc 0.0.0.0:0,tls-creds=tls0
1512 QEMU has a primitive support to work with gdb, so that you can do
1513 'Ctrl-C' while the virtual machine is running and inspect its state.
1515 In order to use gdb, launch QEMU with the '-s' option. It will wait for a
1518 qemu-system-i386 -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
1519 -append "root=/dev/hda"
1520 Connected to host network interface: tun0
1521 Waiting gdb connection on port 1234
1524 Then launch gdb on the 'vmlinux' executable:
1529 In gdb, connect to QEMU:
1531 (gdb) target remote localhost:1234
1534 Then you can use gdb normally. For example, type 'c' to launch the kernel:
1539 Here are some useful tips in order to use gdb on system code:
1543 Use @code{info reg} to display all the CPU registers.
1545 Use @code{x/10i $eip} to display the code at the PC position.
1547 Use @code{set architecture i8086} to dump 16 bit code. Then use
1548 @code{x/10i $cs*16+$eip} to dump the code at the PC position.
1551 Advanced debugging options:
1553 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:
1555 @item maintenance packet qqemu.sstepbits
1557 This will display the MASK bits used to control the single stepping IE:
1559 (gdb) maintenance packet qqemu.sstepbits
1560 sending: "qqemu.sstepbits"
1561 received: "ENABLE=1,NOIRQ=2,NOTIMER=4"
1563 @item maintenance packet qqemu.sstep
1565 This will display the current value of the mask used when single stepping IE:
1567 (gdb) maintenance packet qqemu.sstep
1568 sending: "qqemu.sstep"
1571 @item maintenance packet Qqemu.sstep=HEX_VALUE
1573 This will change the single step mask, so if wanted to enable IRQs on the single step, but not timers, you would use:
1575 (gdb) maintenance packet Qqemu.sstep=0x5
1576 sending: "qemu.sstep=0x5"
1581 @node pcsys_os_specific
1582 @section Target OS specific information
1586 To have access to SVGA graphic modes under X11, use the @code{vesa} or
1587 the @code{cirrus} X11 driver. For optimal performances, use 16 bit
1588 color depth in the guest and the host OS.
1590 When using a 2.6 guest Linux kernel, you should add the option
1591 @code{clock=pit} on the kernel command line because the 2.6 Linux
1592 kernels make very strict real time clock checks by default that QEMU
1593 cannot simulate exactly.
1595 When using a 2.6 guest Linux kernel, verify that the 4G/4G patch is
1596 not activated because QEMU is slower with this patch. The QEMU
1597 Accelerator Module is also much slower in this case. Earlier Fedora
1598 Core 3 Linux kernel (< 2.6.9-1.724_FC3) were known to incorporate this
1599 patch by default. Newer kernels don't have it.
1603 If you have a slow host, using Windows 95 is better as it gives the
1604 best speed. Windows 2000 is also a good choice.
1606 @subsubsection SVGA graphic modes support
1608 QEMU emulates a Cirrus Logic GD5446 Video
1609 card. All Windows versions starting from Windows 95 should recognize
1610 and use this graphic card. For optimal performances, use 16 bit color
1611 depth in the guest and the host OS.
1613 If you are using Windows XP as guest OS and if you want to use high
1614 resolution modes which the Cirrus Logic BIOS does not support (i.e. >=
1615 1280x1024x16), then you should use the VESA VBE virtual graphic card
1616 (option @option{-std-vga}).
1618 @subsubsection CPU usage reduction
1620 Windows 9x does not correctly use the CPU HLT
1621 instruction. The result is that it takes host CPU cycles even when
1622 idle. You can install the utility from
1623 @url{https://web.archive.org/web/20060212132151/http://www.user.cityline.ru/~maxamn/amnhltm.zip}
1624 to solve this problem. Note that no such tool is needed for NT, 2000 or XP.
1626 @subsubsection Windows 2000 disk full problem
1628 Windows 2000 has a bug which gives a disk full problem during its
1629 installation. When installing it, use the @option{-win2k-hack} QEMU
1630 option to enable a specific workaround. After Windows 2000 is
1631 installed, you no longer need this option (this option slows down the
1634 @subsubsection Windows 2000 shutdown
1636 Windows 2000 cannot automatically shutdown in QEMU although Windows 98
1637 can. It comes from the fact that Windows 2000 does not automatically
1638 use the APM driver provided by the BIOS.
1640 In order to correct that, do the following (thanks to Struan
1641 Bartlett): go to the Control Panel => Add/Remove Hardware & Next =>
1642 Add/Troubleshoot a device => Add a new device & Next => No, select the
1643 hardware from a list & Next => NT Apm/Legacy Support & Next => Next
1644 (again) a few times. Now the driver is installed and Windows 2000 now
1645 correctly instructs QEMU to shutdown at the appropriate moment.
1647 @subsubsection Share a directory between Unix and Windows
1649 See @ref{sec_invocation} about the help of the option
1650 @option{'-netdev user,smb=...'}.
1652 @subsubsection Windows XP security problem
1654 Some releases of Windows XP install correctly but give a security
1657 A problem is preventing Windows from accurately checking the
1658 license for this computer. Error code: 0x800703e6.
1661 The workaround is to install a service pack for XP after a boot in safe
1662 mode. Then reboot, and the problem should go away. Since there is no
1663 network while in safe mode, its recommended to download the full
1664 installation of SP1 or SP2 and transfer that via an ISO or using the
1665 vvfat block device ("-hdb fat:directory_which_holds_the_SP").
1667 @subsection MS-DOS and FreeDOS
1669 @subsubsection CPU usage reduction
1671 DOS does not correctly use the CPU HLT instruction. The result is that
1672 it takes host CPU cycles even when idle. You can install the utility from
1673 @url{https://web.archive.org/web/20051222085335/http://www.vmware.com/software/dosidle210.zip}
1674 to solve this problem.
1676 @node QEMU System emulator for non PC targets
1677 @chapter QEMU System emulator for non PC targets
1679 QEMU is a generic emulator and it emulates many non PC
1680 machines. Most of the options are similar to the PC emulator. The
1681 differences are mentioned in the following sections.
1684 * PowerPC System emulator::
1685 * Sparc32 System emulator::
1686 * Sparc64 System emulator::
1687 * MIPS System emulator::
1688 * ARM System emulator::
1689 * ColdFire System emulator::
1690 * Cris System emulator::
1691 * Microblaze System emulator::
1692 * SH4 System emulator::
1693 * Xtensa System emulator::
1696 @node PowerPC System emulator
1697 @section PowerPC System emulator
1698 @cindex system emulation (PowerPC)
1700 Use the executable @file{qemu-system-ppc} to simulate a complete PREP
1701 or PowerMac PowerPC system.
1703 QEMU emulates the following PowerMac peripherals:
1707 UniNorth or Grackle PCI Bridge
1709 PCI VGA compatible card with VESA Bochs Extensions
1711 2 PMAC IDE interfaces with hard disk and CD-ROM support
1717 VIA-CUDA with ADB keyboard and mouse.
1720 QEMU emulates the following PREP peripherals:
1726 PCI VGA compatible card with VESA Bochs Extensions
1728 2 IDE interfaces with hard disk and CD-ROM support
1732 NE2000 network adapters
1736 PREP Non Volatile RAM
1738 PC compatible keyboard and mouse.
1741 QEMU uses the Open Hack'Ware Open Firmware Compatible BIOS available at
1742 @url{http://perso.magic.fr/l_indien/OpenHackWare/index.htm}.
1744 Since version 0.9.1, QEMU uses OpenBIOS @url{https://www.openbios.org/}
1745 for the g3beige and mac99 PowerMac machines. OpenBIOS is a free (GPL
1746 v2) portable firmware implementation. The goal is to implement a 100%
1747 IEEE 1275-1994 (referred to as Open Firmware) compliant firmware.
1749 @c man begin OPTIONS
1751 The following options are specific to the PowerPC emulation:
1755 @item -g @var{W}x@var{H}[x@var{DEPTH}]
1757 Set the initial VGA graphic mode. The default is 800x600x32.
1759 @item -prom-env @var{string}
1761 Set OpenBIOS variables in NVRAM, for example:
1764 qemu-system-ppc -prom-env 'auto-boot?=false' \
1765 -prom-env 'boot-device=hd:2,\yaboot' \
1766 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
1769 These variables are not used by Open Hack'Ware.
1776 More information is available at
1777 @url{http://perso.magic.fr/l_indien/qemu-ppc/}.
1779 @node Sparc32 System emulator
1780 @section Sparc32 System emulator
1781 @cindex system emulation (Sparc32)
1783 Use the executable @file{qemu-system-sparc} to simulate the following
1784 Sun4m architecture machines:
1799 SPARCstation Voyager
1806 The emulation is somewhat complete. SMP up to 16 CPUs is supported,
1807 but Linux limits the number of usable CPUs to 4.
1809 QEMU emulates the following sun4m peripherals:
1815 TCX or cgthree Frame buffer
1817 Lance (Am7990) Ethernet
1819 Non Volatile RAM M48T02/M48T08
1821 Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboard
1822 and power/reset logic
1824 ESP SCSI controller with hard disk and CD-ROM support
1826 Floppy drive (not on SS-600MP)
1828 CS4231 sound device (only on SS-5, not working yet)
1831 The number of peripherals is fixed in the architecture. Maximum
1832 memory size depends on the machine type, for SS-5 it is 256MB and for
1835 Since version 0.8.2, QEMU uses OpenBIOS
1836 @url{https://www.openbios.org/}. OpenBIOS is a free (GPL v2) portable
1837 firmware implementation. The goal is to implement a 100% IEEE
1838 1275-1994 (referred to as Open Firmware) compliant firmware.
1840 A sample Linux 2.6 series kernel and ram disk image are available on
1841 the QEMU web site. There are still issues with NetBSD and OpenBSD, but
1842 most kernel versions work. Please note that currently older Solaris kernels
1843 don't work probably due to interface issues between OpenBIOS and
1846 @c man begin OPTIONS
1848 The following options are specific to the Sparc32 emulation:
1852 @item -g @var{W}x@var{H}x[x@var{DEPTH}]
1854 Set the initial graphics mode. For TCX, the default is 1024x768x8 with the
1855 option of 1024x768x24. For cgthree, the default is 1024x768x8 with the option
1856 of 1152x900x8 for people who wish to use OBP.
1858 @item -prom-env @var{string}
1860 Set OpenBIOS variables in NVRAM, for example:
1863 qemu-system-sparc -prom-env 'auto-boot?=false' \
1864 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
1867 @item -M [SS-4|SS-5|SS-10|SS-20|SS-600MP|LX|Voyager|SPARCClassic] [|SPARCbook]
1869 Set the emulated machine type. Default is SS-5.
1875 @node Sparc64 System emulator
1876 @section Sparc64 System emulator
1877 @cindex system emulation (Sparc64)
1879 Use the executable @file{qemu-system-sparc64} to simulate a Sun4u
1880 (UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic
1881 Niagara (T1) machine. The Sun4u emulator is mostly complete, being
1882 able to run Linux, NetBSD and OpenBSD in headless (-nographic) mode. The
1883 Sun4v emulator is still a work in progress.
1885 The Niagara T1 emulator makes use of firmware and OS binaries supplied in the S10image/ directory
1886 of the OpenSPARC T1 project @url{http://download.oracle.com/technetwork/systems/opensparc/OpenSPARCT1_Arch.1.5.tar.bz2}
1887 and is able to boot the disk.s10hw2 Solaris image.
1889 qemu-system-sparc64 -M niagara -L /path-to/S10image/ \
1891 -drive if=pflash,readonly=on,file=/S10image/disk.s10hw2
1895 QEMU emulates the following peripherals:
1899 UltraSparc IIi APB PCI Bridge
1901 PCI VGA compatible card with VESA Bochs Extensions
1903 PS/2 mouse and keyboard
1905 Non Volatile RAM M48T59
1907 PC-compatible serial ports
1909 2 PCI IDE interfaces with hard disk and CD-ROM support
1914 @c man begin OPTIONS
1916 The following options are specific to the Sparc64 emulation:
1920 @item -prom-env @var{string}
1922 Set OpenBIOS variables in NVRAM, for example:
1925 qemu-system-sparc64 -prom-env 'auto-boot?=false'
1928 @item -M [sun4u|sun4v|niagara]
1930 Set the emulated machine type. The default is sun4u.
1936 @node MIPS System emulator
1937 @section MIPS System emulator
1938 @cindex system emulation (MIPS)
1940 Four executables cover simulation of 32 and 64-bit MIPS systems in
1941 both endian options, @file{qemu-system-mips}, @file{qemu-system-mipsel}
1942 @file{qemu-system-mips64} and @file{qemu-system-mips64el}.
1943 Five different machine types are emulated:
1947 A generic ISA PC-like machine "mips"
1949 The MIPS Malta prototype board "malta"
1951 An ACER Pica "pica61". This machine needs the 64-bit emulator.
1953 MIPS emulator pseudo board "mipssim"
1955 A MIPS Magnum R4000 machine "magnum". This machine needs the 64-bit emulator.
1958 The generic emulation is supported by Debian 'Etch' and is able to
1959 install Debian into a virtual disk image. The following devices are
1964 A range of MIPS CPUs, default is the 24Kf
1966 PC style serial port
1973 The Malta emulation supports the following devices:
1977 Core board with MIPS 24Kf CPU and Galileo system controller
1979 PIIX4 PCI/USB/SMbus controller
1981 The Multi-I/O chip's serial device
1983 PCI network cards (PCnet32 and others)
1985 Malta FPGA serial device
1987 Cirrus (default) or any other PCI VGA graphics card
1990 The ACER Pica emulation supports:
1996 PC-style IRQ and DMA controllers
2003 The mipssim pseudo board emulation provides an environment similar
2004 to what the proprietary MIPS emulator uses for running Linux.
2009 A range of MIPS CPUs, default is the 24Kf
2011 PC style serial port
2013 MIPSnet network emulation
2016 The MIPS Magnum R4000 emulation supports:
2022 PC-style IRQ controller
2032 @node ARM System emulator
2033 @section ARM System emulator
2034 @cindex system emulation (ARM)
2036 Use the executable @file{qemu-system-arm} to simulate a ARM
2037 machine. The ARM Integrator/CP board is emulated with the following
2042 ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
2046 SMC 91c111 Ethernet adapter
2048 PL110 LCD controller
2050 PL050 KMI with PS/2 keyboard and mouse.
2052 PL181 MultiMedia Card Interface with SD card.
2055 The ARM Versatile baseboard is emulated with the following devices:
2059 ARM926E, ARM1136 or Cortex-A8 CPU
2061 PL190 Vectored Interrupt Controller
2065 SMC 91c111 Ethernet adapter
2067 PL110 LCD controller
2069 PL050 KMI with PS/2 keyboard and mouse.
2071 PCI host bridge. Note the emulated PCI bridge only provides access to
2072 PCI memory space. It does not provide access to PCI IO space.
2073 This means some devices (eg. ne2k_pci NIC) are not usable, and others
2074 (eg. rtl8139 NIC) are only usable when the guest drivers use the memory
2075 mapped control registers.
2077 PCI OHCI USB controller.
2079 LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices.
2081 PL181 MultiMedia Card Interface with SD card.
2084 Several variants of the ARM RealView baseboard are emulated,
2085 including the EB, PB-A8 and PBX-A9. Due to interactions with the
2086 bootloader, only certain Linux kernel configurations work out
2087 of the box on these boards.
2089 Kernels for the PB-A8 board should have CONFIG_REALVIEW_HIGH_PHYS_OFFSET
2090 enabled in the kernel, and expect 512M RAM. Kernels for The PBX-A9 board
2091 should have CONFIG_SPARSEMEM enabled, CONFIG_REALVIEW_HIGH_PHYS_OFFSET
2092 disabled and expect 1024M RAM.
2094 The following devices are emulated:
2098 ARM926E, ARM1136, ARM11MPCore, Cortex-A8 or Cortex-A9 MPCore CPU
2100 ARM AMBA Generic/Distributed Interrupt Controller
2104 SMC 91c111 or SMSC LAN9118 Ethernet adapter
2106 PL110 LCD controller
2108 PL050 KMI with PS/2 keyboard and mouse
2112 PCI OHCI USB controller
2114 LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices
2116 PL181 MultiMedia Card Interface with SD card.
2119 The XScale-based clamshell PDA models ("Spitz", "Akita", "Borzoi"
2120 and "Terrier") emulation includes the following peripherals:
2124 Intel PXA270 System-on-chip (ARM V5TE core)
2128 IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in "Akita"
2130 On-chip OHCI USB controller
2132 On-chip LCD controller
2134 On-chip Real Time Clock
2136 TI ADS7846 touchscreen controller on SSP bus
2138 Maxim MAX1111 analog-digital converter on I@math{^2}C bus
2140 GPIO-connected keyboard controller and LEDs
2142 Secure Digital card connected to PXA MMC/SD host
2146 WM8750 audio CODEC on I@math{^2}C and I@math{^2}S busses
2149 The Palm Tungsten|E PDA (codename "Cheetah") emulation includes the
2154 Texas Instruments OMAP310 System-on-chip (ARM 925T core)
2156 ROM and RAM memories (ROM firmware image can be loaded with -option-rom)
2158 On-chip LCD controller
2160 On-chip Real Time Clock
2162 TI TSC2102i touchscreen controller / analog-digital converter / Audio
2163 CODEC, connected through MicroWire and I@math{^2}S busses
2165 GPIO-connected matrix keypad
2167 Secure Digital card connected to OMAP MMC/SD host
2172 Nokia N800 and N810 internet tablets (known also as RX-34 and RX-44 / 48)
2173 emulation supports the following elements:
2177 Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)
2179 RAM and non-volatile OneNAND Flash memories
2181 Display connected to EPSON remote framebuffer chip and OMAP on-chip
2182 display controller and a LS041y3 MIPI DBI-C controller
2184 TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen controllers
2185 driven through SPI bus
2187 National Semiconductor LM8323-controlled qwerty keyboard driven
2188 through I@math{^2}C bus
2190 Secure Digital card connected to OMAP MMC/SD host
2192 Three OMAP on-chip UARTs and on-chip STI debugging console
2194 A Bluetooth(R) transceiver and HCI connected to an UART
2196 Mentor Graphics "Inventra" dual-role USB controller embedded in a TI
2197 TUSB6010 chip - only USB host mode is supported
2199 TI TMP105 temperature sensor driven through I@math{^2}C bus
2201 TI TWL92230C power management companion with an RTC on I@math{^2}C bus
2203 Nokia RETU and TAHVO multi-purpose chips with an RTC, connected
2207 The Luminary Micro Stellaris LM3S811EVB emulation includes the following
2214 64k Flash and 8k SRAM.
2216 Timers, UARTs, ADC and I@math{^2}C interface.
2218 OSRAM Pictiva 96x16 OLED with SSD0303 controller on I@math{^2}C bus.
2221 The Luminary Micro Stellaris LM3S6965EVB emulation includes the following
2228 256k Flash and 64k SRAM.
2230 Timers, UARTs, ADC, I@math{^2}C and SSI interfaces.
2232 OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via SSI.
2235 The Freecom MusicPal internet radio emulation includes the following
2240 Marvell MV88W8618 ARM core.
2242 32 MB RAM, 256 KB SRAM, 8 MB flash.
2246 MV88W8xx8 Ethernet controller
2248 MV88W8618 audio controller, WM8750 CODEC and mixer
2250 128×64 display with brightness control
2252 2 buttons, 2 navigation wheels with button function
2255 The Siemens SX1 models v1 and v2 (default) basic emulation.
2256 The emulation includes the following elements:
2260 Texas Instruments OMAP310 System-on-chip (ARM 925T core)
2262 ROM and RAM memories (ROM firmware image can be loaded with -pflash)
2264 1 Flash of 16MB and 1 Flash of 8MB
2268 On-chip LCD controller
2270 On-chip Real Time Clock
2272 Secure Digital card connected to OMAP MMC/SD host
2277 A Linux 2.6 test image is available on the QEMU web site. More
2278 information is available in the QEMU mailing-list archive.
2280 @c man begin OPTIONS
2282 The following options are specific to the ARM emulation:
2287 Enable semihosting syscall emulation.
2289 On ARM this implements the "Angel" interface.
2291 Note that this allows guest direct access to the host filesystem,
2292 so should only be used with trusted guest OS.
2298 @node ColdFire System emulator
2299 @section ColdFire System emulator
2300 @cindex system emulation (ColdFire)
2301 @cindex system emulation (M68K)
2303 Use the executable @file{qemu-system-m68k} to simulate a ColdFire machine.
2304 The emulator is able to boot a uClinux kernel.
2306 The M5208EVB emulation includes the following devices:
2310 MCF5208 ColdFire V2 Microprocessor (ISA A+ with EMAC).
2312 Three Two on-chip UARTs.
2314 Fast Ethernet Controller (FEC)
2317 The AN5206 emulation includes the following devices:
2321 MCF5206 ColdFire V2 Microprocessor.
2326 @c man begin OPTIONS
2328 The following options are specific to the ColdFire emulation:
2333 Enable semihosting syscall emulation.
2335 On M68K this implements the "ColdFire GDB" interface used by libgloss.
2337 Note that this allows guest direct access to the host filesystem,
2338 so should only be used with trusted guest OS.
2344 @node Cris System emulator
2345 @section Cris System emulator
2346 @cindex system emulation (Cris)
2350 @node Microblaze System emulator
2351 @section Microblaze System emulator
2352 @cindex system emulation (Microblaze)
2356 @node SH4 System emulator
2357 @section SH4 System emulator
2358 @cindex system emulation (SH4)
2362 @node Xtensa System emulator
2363 @section Xtensa System emulator
2364 @cindex system emulation (Xtensa)
2366 Two executables cover simulation of both Xtensa endian options,
2367 @file{qemu-system-xtensa} and @file{qemu-system-xtensaeb}.
2368 Two different machine types are emulated:
2372 Xtensa emulator pseudo board "sim"
2374 Avnet LX60/LX110/LX200 board
2377 The sim pseudo board emulation provides an environment similar
2378 to one provided by the proprietary Tensilica ISS.
2383 A range of Xtensa CPUs, default is the DC232B
2385 Console and filesystem access via semihosting calls
2388 The Avnet LX60/LX110/LX200 emulation supports:
2392 A range of Xtensa CPUs, default is the DC232B
2396 OpenCores 10/100 Mbps Ethernet MAC
2399 @c man begin OPTIONS
2401 The following options are specific to the Xtensa emulation:
2406 Enable semihosting syscall emulation.
2408 Xtensa semihosting provides basic file IO calls, such as open/read/write/seek/select.
2409 Tensilica baremetal libc for ISS and linux platform "sim" use this interface.
2411 Note that this allows guest direct access to the host filesystem,
2412 so should only be used with trusted guest OS.
2418 @node QEMU Guest Agent
2419 @chapter QEMU Guest Agent invocation
2421 @include qemu-ga.texi
2423 @node QEMU User space emulator
2424 @chapter QEMU User space emulator
2427 * Supported Operating Systems ::
2429 * Linux User space emulator::
2430 * BSD User space emulator ::
2433 @node Supported Operating Systems
2434 @section Supported Operating Systems
2436 The following OS are supported in user space emulation:
2440 Linux (referred as qemu-linux-user)
2442 BSD (referred as qemu-bsd-user)
2448 QEMU user space emulation has the following notable features:
2451 @item System call translation:
2452 QEMU includes a generic system call translator. This means that
2453 the parameters of the system calls can be converted to fix
2454 endianness and 32/64-bit mismatches between hosts and targets.
2455 IOCTLs can be converted too.
2457 @item POSIX signal handling:
2458 QEMU can redirect to the running program all signals coming from
2459 the host (such as @code{SIGALRM}), as well as synthesize signals from
2460 virtual CPU exceptions (for example @code{SIGFPE} when the program
2461 executes a division by zero).
2463 QEMU relies on the host kernel to emulate most signal system
2464 calls, for example to emulate the signal mask. On Linux, QEMU
2465 supports both normal and real-time signals.
2468 On Linux, QEMU can emulate the @code{clone} syscall and create a real
2469 host thread (with a separate virtual CPU) for each emulated thread.
2470 Note that not all targets currently emulate atomic operations correctly.
2471 x86 and ARM use a global lock in order to preserve their semantics.
2474 QEMU was conceived so that ultimately it can emulate itself. Although
2475 it is not very useful, it is an important test to show the power of the
2478 @node Linux User space emulator
2479 @section Linux User space emulator
2484 * Command line options::
2489 @subsection Quick Start
2491 In order to launch a Linux process, QEMU needs the process executable
2492 itself and all the target (x86) dynamic libraries used by it.
2496 @item On x86, you can just try to launch any process by using the native
2500 qemu-i386 -L / /bin/ls
2503 @code{-L /} tells that the x86 dynamic linker must be searched with a
2506 @item Since QEMU is also a linux process, you can launch QEMU with
2507 QEMU (NOTE: you can only do that if you compiled QEMU from the sources):
2510 qemu-i386 -L / qemu-i386 -L / /bin/ls
2513 @item On non x86 CPUs, you need first to download at least an x86 glibc
2514 (@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
2515 @code{LD_LIBRARY_PATH} is not set:
2518 unset LD_LIBRARY_PATH
2521 Then you can launch the precompiled @file{ls} x86 executable:
2524 qemu-i386 tests/i386/ls
2526 You can look at @file{scripts/qemu-binfmt-conf.sh} so that
2527 QEMU is automatically launched by the Linux kernel when you try to
2528 launch x86 executables. It requires the @code{binfmt_misc} module in the
2531 @item The x86 version of QEMU is also included. You can try weird things such as:
2533 qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 \
2534 /usr/local/qemu-i386/bin/ls-i386
2540 @subsection Wine launch
2544 @item Ensure that you have a working QEMU with the x86 glibc
2545 distribution (see previous section). In order to verify it, you must be
2549 qemu-i386 /usr/local/qemu-i386/bin/ls-i386
2552 @item Download the binary x86 Wine install
2553 (@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page).
2555 @item Configure Wine on your account. Look at the provided script
2556 @file{/usr/local/qemu-i386/@/bin/wine-conf.sh}. Your previous
2557 @code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.
2559 @item Then you can try the example @file{putty.exe}:
2562 qemu-i386 /usr/local/qemu-i386/wine/bin/wine \
2563 /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
2568 @node Command line options
2569 @subsection Command line options
2572 @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}...]
2579 Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
2581 Set the x86 stack size in bytes (default=524288)
2583 Select CPU model (-cpu help for list and additional feature selection)
2584 @item -E @var{var}=@var{value}
2585 Set environment @var{var} to @var{value}.
2587 Remove @var{var} from the environment.
2589 Offset guest address by the specified number of bytes. This is useful when
2590 the address region required by guest applications is reserved on the host.
2591 This option is currently only supported on some hosts.
2593 Pre-allocate a guest virtual address space of the given size (in bytes).
2594 "G", "M", and "k" suffixes may be used when specifying the size.
2601 Activate logging of the specified items (use '-d help' for a list of log items)
2603 Act as if the host page size was 'pagesize' bytes
2605 Wait gdb connection to port
2607 Run the emulation in single step mode.
2610 Environment variables:
2614 Print system calls and arguments similar to the 'strace' program
2615 (NOTE: the actual 'strace' program will not work because the user
2616 space emulator hasn't implemented ptrace). At the moment this is
2617 incomplete. All system calls that don't have a specific argument
2618 format are printed with information for six arguments. Many
2619 flag-style arguments don't have decoders and will show up as numbers.
2622 @node Other binaries
2623 @subsection Other binaries
2625 @cindex user mode (Alpha)
2626 @command{qemu-alpha} TODO.
2628 @cindex user mode (ARM)
2629 @command{qemu-armeb} TODO.
2631 @cindex user mode (ARM)
2632 @command{qemu-arm} is also capable of running ARM "Angel" semihosted ELF
2633 binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
2634 configurations), and arm-uclinux bFLT format binaries.
2636 @cindex user mode (ColdFire)
2637 @cindex user mode (M68K)
2638 @command{qemu-m68k} is capable of running semihosted binaries using the BDM
2639 (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
2640 coldfire uClinux bFLT format binaries.
2642 The binary format is detected automatically.
2644 @cindex user mode (Cris)
2645 @command{qemu-cris} TODO.
2647 @cindex user mode (i386)
2648 @command{qemu-i386} TODO.
2649 @command{qemu-x86_64} TODO.
2651 @cindex user mode (Microblaze)
2652 @command{qemu-microblaze} TODO.
2654 @cindex user mode (MIPS)
2655 @command{qemu-mips} TODO.
2656 @command{qemu-mipsel} TODO.
2658 @cindex user mode (NiosII)
2659 @command{qemu-nios2} TODO.
2661 @cindex user mode (PowerPC)
2662 @command{qemu-ppc64abi32} TODO.
2663 @command{qemu-ppc64} TODO.
2664 @command{qemu-ppc} TODO.
2666 @cindex user mode (SH4)
2667 @command{qemu-sh4eb} TODO.
2668 @command{qemu-sh4} TODO.
2670 @cindex user mode (SPARC)
2671 @command{qemu-sparc} can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
2673 @command{qemu-sparc32plus} can execute Sparc32 and SPARC32PLUS binaries
2674 (Sparc64 CPU, 32 bit ABI).
2676 @command{qemu-sparc64} can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
2677 SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
2679 @node BSD User space emulator
2680 @section BSD User space emulator
2685 * BSD Command line options::
2689 @subsection BSD Status
2693 target Sparc64 on Sparc64: Some trivial programs work.
2696 @node BSD Quick Start
2697 @subsection Quick Start
2699 In order to launch a BSD process, QEMU needs the process executable
2700 itself and all the target dynamic libraries used by it.
2704 @item On Sparc64, you can just try to launch any process by using the native
2708 qemu-sparc64 /bin/ls
2713 @node BSD Command line options
2714 @subsection Command line options
2717 @command{qemu-sparc64} [@option{-h]} [@option{-d]} [@option{-L} @var{path}] [@option{-s} @var{size}] [@option{-bsd} @var{type}] @var{program} [@var{arguments}...]
2724 Set the library root path (default=/)
2726 Set the stack size in bytes (default=524288)
2727 @item -ignore-environment
2728 Start with an empty environment. Without this option,
2729 the initial environment is a copy of the caller's environment.
2730 @item -E @var{var}=@var{value}
2731 Set environment @var{var} to @var{value}.
2733 Remove @var{var} from the environment.
2735 Set the type of the emulated BSD Operating system. Valid values are
2736 FreeBSD, NetBSD and OpenBSD (default).
2743 Activate logging of the specified items (use '-d help' for a list of log items)
2745 Act as if the host page size was 'pagesize' bytes
2747 Run the emulation in single step mode.
2751 @include qemu-tech.texi
2753 @node Deprecated features
2754 @appendix Deprecated features
2756 In general features are intended to be supported indefinitely once
2757 introduced into QEMU. In the event that a feature needs to be removed,
2758 it will be listed in this appendix. The feature will remain functional
2759 for 2 releases prior to actual removal. Deprecated features may also
2760 generate warnings on the console when QEMU starts up, or if activated
2761 via a monitor command, however, this is not a mandatory requirement.
2763 Prior to the 2.10.0 release there was no official policy on how
2764 long features would be deprecated prior to their removal, nor
2765 any documented list of which features were deprecated. Thus
2766 any features deprecated prior to 2.10.0 will be treated as if
2767 they were first deprecated in the 2.10.0 release.
2769 What follows is a list of all features currently marked as
2772 @section Build options
2776 Previously QEMU has supported building against both GTK 2.x
2777 and 3.x series APIs. Support for the GTK 2.x builds will be
2778 discontinued, so maintainers should switch to using GTK 3.x,
2779 which is the default.
2783 Previously QEMU has supported building against both SDL 1.2
2784 and 2.0 series APIs. Support for the SDL 1.2 builds will be
2785 discontinued, so maintainers should switch to using SDL 2.0,
2786 which is the default.
2788 @section System emulator command line arguments
2790 @subsection -no-kvm (since 1.3.0)
2792 The ``-no-kvm'' argument is now a synonym for setting
2793 ``-machine accel=tcg''.
2795 @subsection -vnc tls (since 2.5.0)
2797 The ``-vnc tls'' argument is now a synonym for setting
2798 ``-object tls-creds-anon,id=tls0'' combined with
2799 ``-vnc tls-creds=tls0'
2801 @subsection -vnc x509 (since 2.5.0)
2803 The ``-vnc x509=/path/to/certs'' argument is now a
2805 ``-object tls-creds-x509,dir=/path/to/certs,id=tls0,verify-peer=no''
2806 combined with ``-vnc tls-creds=tls0'
2808 @subsection -vnc x509verify (since 2.5.0)
2810 The ``-vnc x509verify=/path/to/certs'' argument is now a
2812 ``-object tls-creds-x509,dir=/path/to/certs,id=tls0,verify-peer=yes''
2813 combined with ``-vnc tls-creds=tls0'
2815 @subsection -tftp (since 2.6.0)
2817 The ``-tftp /some/dir'' argument is replaced by either
2818 ``-netdev user,id=x,tftp=/some/dir '' (for pluggable NICs, accompanied
2819 with ``-device ...,netdev=x''), or ``-nic user,tftp=/some/dir''
2820 (for embedded NICs). The new syntax allows different settings to be
2823 @subsection -bootp (since 2.6.0)
2825 The ``-bootp /some/file'' argument is replaced by either
2826 ``-netdev user,id=x,bootp=/some/file '' (for pluggable NICs, accompanied
2827 with ``-device ...,netdev=x''), or ``-nic user,bootp=/some/file''
2828 (for embedded NICs). The new syntax allows different settings to be
2831 @subsection -redir (since 2.6.0)
2833 The ``-redir [tcp|udp]:hostport:[guestaddr]:guestport'' argument is
2835 ``-netdev user,id=x,hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport''
2836 (for pluggable NICs, accompanied with ``-device ...,netdev=x'') or
2837 ``-nic user,hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport''
2838 (for embedded NICs). The new syntax allows different settings to be
2841 @subsection -smb (since 2.6.0)
2843 The ``-smb /some/dir'' argument is replaced by either
2844 ``-netdev user,id=x,smb=/some/dir '' (for pluggable NICs, accompanied
2845 with ``-device ...,netdev=x''), or ``-nic user,smb=/some/dir''
2846 (for embedded NICs). The new syntax allows different settings to be
2849 @subsection -net vlan (since 2.9.0)
2851 The ``-net vlan=NN'' argument was mostly used to attach separate
2852 network backends to different virtual NICs. This is the default
2853 behavior for ``-netdev'' and ``-nic''. You can connect multiple
2854 ``-netdev'' and ``-nic'' devices to the same network using the
2855 "hubport" network backend, created with ``-netdev hubport,hubid=NN,...''
2856 and ``-nic hubport,hubid=NN''.
2858 @subsection -drive cyls=...,heads=...,secs=...,trans=... (since 2.10.0)
2860 The drive geometry arguments are replaced by the the geometry arguments
2861 that can be specified with the ``-device'' parameter.
2863 @subsection -drive serial=... (since 2.10.0)
2865 The drive serial argument is replaced by the the serial argument
2866 that can be specified with the ``-device'' parameter.
2868 @subsection -drive addr=... (since 2.10.0)
2870 The drive addr argument is replaced by the the addr argument
2871 that can be specified with the ``-device'' parameter.
2873 @subsection -usbdevice (since 2.10.0)
2875 The ``-usbdevice DEV'' argument is now a synonym for setting
2876 the ``-device usb-DEV'' argument instead. The deprecated syntax
2877 would automatically enable USB support on the machine type.
2878 If using the new syntax, USB support must be explicitly
2879 enabled via the ``-machine usb=on'' argument.
2881 @subsection -nodefconfig (since 2.11.0)
2883 The ``-nodefconfig`` argument is a synonym for ``-no-user-config``.
2885 @subsection -balloon (since 2.12.0)
2887 The @option{--balloon virtio} argument has been superseded by
2888 @option{--device virtio-balloon}.
2890 @subsection -machine s390-squash-mcss=on|off (since 2.12.0)
2892 The ``s390-squash-mcss=on`` property has been obsoleted by allowing the
2893 cssid to be chosen freely. Instead of squashing subchannels into the
2894 default channel subsystem image for guests that do not support multiple
2895 channel subsystems, all devices can be put into the default channel
2898 @subsection -fsdev handle (since 2.12.0)
2900 The ``handle'' fsdev backend does not support symlinks and causes the 9p
2901 filesystem in the guest to fail a fair amount of tests from the PJD POSIX
2902 filesystem test suite. Also it requires the CAP_DAC_READ_SEARCH capability,
2903 which is not the recommended way to run QEMU. This backend should not be
2904 used and it will be removed with no replacement.
2906 @subsection -no-frame (since 2.12.0)
2908 The @code{--no-frame} argument works with SDL 1.2 only. The other user
2909 interfaces never implemented this in the first place. So this will be
2910 removed together with SDL 1.2 support.
2912 @subsection -rtc-td-hack (since 2.12.0)
2914 The @code{-rtc-td-hack} option has been replaced by
2915 @code{-rtc driftfix=slew}.
2917 @subsection -localtime (since 2.12.0)
2919 The @code{-localtime} option has been replaced by @code{-rtc base=localtime}.
2921 @subsection -startdate (since 2.12.0)
2923 The @code{-startdate} option has been replaced by @code{-rtc base=@var{date}}.
2925 @subsection -virtioconsole (since 2.13.0)
2927 Option @option{-virtioconsole} has been replaced by
2928 @option{-device virtconsole}.
2930 @section qemu-img command line arguments
2932 @subsection convert -s (since 2.0.0)
2934 The ``convert -s snapshot_id_or_name'' argument is obsoleted
2935 by the ``convert -l snapshot_param'' argument instead.
2937 @section QEMU Machine Protocol (QMP) commands
2939 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
2941 "autoload" parameter is now ignored. All bitmaps are automatically loaded
2944 @subsection query-cpus (since 2.12.0)
2946 The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
2948 @subsection query-cpus-fast "arch" output member (since 2.13.0)
2950 The ``arch'' output member of the ``query-cpus-fast'' command is
2951 replaced by the ``target'' output member.
2953 @section System emulator devices
2955 @subsection ivshmem (since 2.6.0)
2957 The ``ivshmem'' device type is replaced by either the ``ivshmem-plain''
2958 or ``ivshmem-doorbell`` device types.
2960 @subsection Page size support < 4k for embedded PowerPC CPUs (since 2.12.0)
2962 qemu-system-ppcemb will be removed. qemu-system-ppc (or qemu-system-ppc64)
2963 should be used instead. That means that embedded 4xx PowerPC CPUs will not
2964 support page sizes < 4096 any longer.
2966 @section System emulator machines
2968 @subsection Xilinx EP108 (since 2.11.0)
2970 The ``xlnx-ep108'' machine has been replaced by the ``xlnx-zcu102'' machine.
2971 The ``xlnx-zcu102'' machine has the same features and capabilites in QEMU.
2973 @section Block device options
2975 @subsection "backing": "" (since 2.12.0)
2977 In order to prevent QEMU from automatically opening an image's backing
2978 chain, use ``"backing": null'' instead.
2980 @node Supported build platforms
2981 @appendix Supported build platforms
2983 QEMU aims to support building and executing on multiple host OS platforms.
2984 This appendix outlines which platforms are the major build targets. These
2985 platforms are used as the basis for deciding upon the minimum required
2986 versions of 3rd party software QEMU depends on. The supported platforms
2987 are the targets for automated testing performed by the project when patches
2988 are submitted for review, and tested before and after merge.
2990 If a platform is not listed here, it does not imply that QEMU won't work.
2991 If an unlisted platform has comparable software versions to a listed platform,
2992 there is every expectation that it will work. Bug reports are welcome for
2993 problems encountered on unlisted platforms unless they are clearly older
2994 vintage than what is described here.
2996 Note that when considering software versions shipped in distros as support
2997 targets, QEMU considers only the version number, and assumes the features in
2998 that distro match the upstream release with the same version. In other words,
2999 if a distro backports extra features to the software in their distro, QEMU
3000 upstream code will not add explicit support for those backports, unless the
3001 feature is auto-detectable in a manner that works for the upstream releases
3004 The Repology site @url{https://repology.org} is a useful resource to identify
3005 currently shipped versions of software in various operating systems, though
3006 it does not cover all distros listed below.
3010 For distributions with frequent, short-lifetime releases, the project will
3011 aim to support all versions that are not end of life by their respective
3012 vendors. For the purposes of identifying supported software versions, the
3013 project will look at Fedora, Ubuntu, and openSUSE distros. Other short-
3014 lifetime distros will be assumed to ship similar software versions.
3016 For distributions with long-lifetime releases, the project will aim to support
3017 the most recent major version at all times. Support for the previous major
3018 version will be dropped 2 years after the new major version is released. For
3019 the purposes of identifying supported software versions, the project will look
3020 at RHEL, Debian, Ubuntu LTS, and SLES distros. Other long-lifetime distros will
3021 be assumed to ship similar software versions.
3025 The project supports building with current versions of the MinGW toolchain,
3030 The project supports building with the two most recent versions of macOS, with
3031 the current homebrew package set available.
3035 The project aims to support the all the versions which are not end of life.
3039 The project aims to support the most recent major version at all times. Support
3040 for the previous major version will be dropped 2 years after the new major
3041 version is released.
3045 The project aims to support the all the versions which are not end of life.
3050 QEMU is a trademark of Fabrice Bellard.
3052 QEMU is released under the
3053 @url{https://www.gnu.org/licenses/gpl-2.0.txt,GNU General Public License},
3054 version 2. Parts of QEMU have specific licenses, see file
3055 @url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE,LICENSE}.
3069 @section Concept Index
3070 This is the main index. Should we combine all keywords in one index? TODO
3073 @node Function Index
3074 @section Function Index
3075 This index could be used for command line options and monitor functions.
3078 @node Keystroke Index
3079 @section Keystroke Index
3081 This is a list of all keystrokes which have a special function
3082 in system emulation.
3087 @section Program Index
3090 @node Data Type Index
3091 @section Data Type Index
3093 This index could be used for qdev device names and options.
3097 @node Variable Index
3098 @section Variable Index