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::
53 * intro_features:: Features
59 QEMU is a FAST! processor emulator using dynamic translation to
60 achieve good emulation speed.
62 @cindex operating modes
63 QEMU has two operating modes:
66 @cindex system emulation
67 @item Full system emulation. In this mode, QEMU emulates a full system (for
68 example a PC), including one or several processors and various
69 peripherals. It can be used to launch different Operating Systems
70 without rebooting the PC or to debug system code.
72 @cindex user mode emulation
73 @item User mode emulation. In this mode, QEMU can launch
74 processes compiled for one CPU on another CPU. It can be used to
75 launch the Wine Windows API emulator (@url{https://www.winehq.org}) or
76 to ease cross-compilation and cross-debugging.
80 QEMU has the following features:
83 @item QEMU can run without a host kernel driver and yet gives acceptable
84 performance. It uses dynamic translation to native code for reasonable speed,
85 with support for self-modifying code and precise exceptions.
87 @item It is portable to several operating systems (GNU/Linux, *BSD, Mac OS X,
88 Windows) and architectures.
90 @item It performs accurate software emulation of the FPU.
93 QEMU user mode emulation has the following features:
95 @item Generic Linux system call converter, including most ioctls.
97 @item clone() emulation using native CPU clone() to use Linux scheduler for threads.
99 @item Accurate signal handling by remapping host signals to target signals.
102 QEMU full system emulation has the following features:
105 QEMU uses a full software MMU for maximum portability.
108 QEMU can optionally use an in-kernel accelerator, like kvm. The accelerators
109 execute most of the guest code natively, while
110 continuing to emulate the rest of the machine.
113 Various hardware devices can be emulated and in some cases, host
114 devices (e.g. serial and parallel ports, USB, drives) can be used
115 transparently by the guest Operating System. Host device passthrough
116 can be used for talking to external physical peripherals (e.g. a
117 webcam, modem or tape drive).
120 Symmetric multiprocessing (SMP) support. Currently, an in-kernel
121 accelerator is required to use more than one host CPU for emulation.
126 @node QEMU PC System emulator
127 @chapter QEMU PC System emulator
128 @cindex system emulation (PC)
131 * pcsys_introduction:: Introduction
132 * pcsys_quickstart:: Quick Start
133 * sec_invocation:: Invocation
134 * pcsys_keys:: Keys in the graphical frontends
135 * mux_keys:: Keys in the character backend multiplexer
136 * pcsys_monitor:: QEMU Monitor
137 * disk_images:: Disk Images
138 * pcsys_network:: Network emulation
139 * pcsys_other_devs:: Other Devices
140 * direct_linux_boot:: Direct Linux Boot
141 * pcsys_usb:: USB emulation
142 * vnc_security:: VNC security
143 * network_tls:: TLS setup for network services
144 * gdb_usage:: GDB usage
145 * pcsys_os_specific:: Target OS specific information
148 @node pcsys_introduction
149 @section Introduction
151 @c man begin DESCRIPTION
153 The QEMU PC System emulator simulates the
154 following peripherals:
158 i440FX host PCI bridge and PIIX3 PCI to ISA bridge
160 Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
161 extensions (hardware level, including all non standard modes).
163 PS/2 mouse and keyboard
165 2 PCI IDE interfaces with hard disk and CD-ROM support
169 PCI and ISA network adapters
173 IPMI BMC, either and internal or external one
175 Creative SoundBlaster 16 sound card
177 ENSONIQ AudioPCI ES1370 sound card
179 Intel 82801AA AC97 Audio compatible sound card
181 Intel HD Audio Controller and HDA codec
183 Adlib (OPL2) - Yamaha YM3812 compatible chip
185 Gravis Ultrasound GF1 sound card
187 CS4231A compatible sound card
189 PCI UHCI, OHCI, EHCI or XHCI USB controller and a virtual USB-1.1 hub.
192 SMP is supported with up to 255 CPUs.
194 QEMU uses the PC BIOS from the Seabios project and the Plex86/Bochs LGPL
197 QEMU uses YM3812 emulation by Tatsuyuki Satoh.
199 QEMU uses GUS emulation (GUSEMU32 @url{http://www.deinmeister.de/gusemu/})
200 by Tibor "TS" Schütz.
202 Note that, by default, GUS shares IRQ(7) with parallel ports and so
203 QEMU must be told to not have parallel ports to have working GUS.
206 qemu-system-i386 dos.img -soundhw gus -parallel none
211 qemu-system-i386 dos.img -device gus,irq=5
214 Or some other unclaimed IRQ.
216 CS4231A is the chip used in Windows Sound System and GUSMAX products
220 @node pcsys_quickstart
224 Download and uncompress the linux image (@file{linux.img}) and type:
227 qemu-system-i386 linux.img
230 Linux should boot and give you a prompt.
236 @c man begin SYNOPSIS
237 @command{qemu-system-i386} [@var{options}] [@var{disk_image}]
242 @var{disk_image} is a raw hard disk image for IDE hard disk 0. Some
243 targets do not need a disk image.
245 @include qemu-options.texi
249 @subsection Device URL Syntax
250 @c TODO merge this with section Disk Images
254 In addition to using normal file images for the emulated storage devices,
255 QEMU can also use networked resources such as iSCSI devices. These are
256 specified using a special URL syntax.
260 iSCSI support allows QEMU to access iSCSI resources directly and use as
261 images for the guest storage. Both disk and cdrom images are supported.
263 Syntax for specifying iSCSI LUNs is
264 ``iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>''
266 By default qemu will use the iSCSI initiator-name
267 'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command
268 line or a configuration file.
270 Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect
271 stalled requests and force a reestablishment of the session. The timeout
272 is specified in seconds. The default is 0 which means no timeout. Libiscsi
273 1.15.0 or greater is required for this feature.
275 Example (without authentication):
277 qemu-system-i386 -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \
278 -cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \
279 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
282 Example (CHAP username/password via URL):
284 qemu-system-i386 -drive file=iscsi://user%password@@192.0.2.1/iqn.2001-04.com.example/1
287 Example (CHAP username/password via environment variables):
289 LIBISCSI_CHAP_USERNAME="user" \
290 LIBISCSI_CHAP_PASSWORD="password" \
291 qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
295 QEMU supports NBD (Network Block Devices) both using TCP protocol as well
296 as Unix Domain Sockets.
298 Syntax for specifying a NBD device using TCP
299 ``nbd:<server-ip>:<port>[:exportname=<export>]''
301 Syntax for specifying a NBD device using Unix Domain Sockets
302 ``nbd:unix:<domain-socket>[:exportname=<export>]''
306 qemu-system-i386 --drive file=nbd:192.0.2.1:30000
309 Example for Unix Domain Sockets
311 qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket
315 QEMU supports SSH (Secure Shell) access to remote disks.
319 qemu-system-i386 -drive file=ssh://user@@host/path/to/disk.img
320 qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
323 Currently authentication must be done using ssh-agent. Other
324 authentication methods may be supported in future.
327 Sheepdog is a distributed storage system for QEMU.
328 QEMU supports using either local sheepdog devices or remote networked
331 Syntax for specifying a sheepdog device
333 sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]
338 qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
341 See also @url{https://sheepdog.github.io/sheepdog/}.
344 GlusterFS is a user space distributed file system.
345 QEMU supports the use of GlusterFS volumes for hosting VM disk images using
346 TCP, Unix Domain Sockets and RDMA transport protocols.
348 Syntax for specifying a VM disk image on GlusterFS volume is
352 gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...]
355 'json:@{"driver":"qcow2","file":@{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...",
356 @ "server":[@{"type":"tcp","host":"...","port":"..."@},
357 @ @{"type":"unix","socket":"..."@}]@}@}'
364 qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img,
365 @ file.debug=9,file.logfile=/var/log/qemu-gluster.log
368 qemu-system-x86_64 'json:@{"driver":"qcow2",
369 @ "file":@{"driver":"gluster",
370 @ "volume":"testvol","path":"a.img",
371 @ "debug":9,"logfile":"/var/log/qemu-gluster.log",
372 @ "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@},
373 @ @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}'
374 qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
375 @ file.debug=9,file.logfile=/var/log/qemu-gluster.log,
376 @ file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
377 @ file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
380 See also @url{http://www.gluster.org}.
382 @item HTTP/HTTPS/FTP/FTPS
383 QEMU supports read-only access to files accessed over http(s) and ftp(s).
385 Syntax using a single filename:
387 <protocol>://[<username>[:<password>]@@]<host>/<path>
393 'http', 'https', 'ftp', or 'ftps'.
396 Optional username for authentication to the remote server.
399 Optional password for authentication to the remote server.
402 Address of the remote server.
405 Path on the remote server, including any query string.
408 The following options are also supported:
411 The full URL when passing options to the driver explicitly.
414 The amount of data to read ahead with each range request to the remote server.
415 This value may optionally have the suffix 'T', 'G', 'M', 'K', 'k' or 'b'. If it
416 does not have a suffix, it will be assumed to be in bytes. The value must be a
417 multiple of 512 bytes. It defaults to 256k.
420 Whether to verify the remote server's certificate when connecting over SSL. It
421 can have the value 'on' or 'off'. It defaults to 'on'.
424 Send this cookie (it can also be a list of cookies separated by ';') with
425 each outgoing request. Only supported when using protocols such as HTTP
426 which support cookies, otherwise ignored.
429 Set the timeout in seconds of the CURL connection. This timeout is the time
430 that CURL waits for a response from the remote server to get the size of the
431 image to be downloaded. If not set, the default timeout of 5 seconds is used.
434 Note that when passing options to qemu explicitly, @option{driver} is the value
437 Example: boot from a remote Fedora 20 live ISO image
439 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
441 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
444 Example: boot from a remote Fedora 20 cloud image using a local overlay for
445 writes, copy-on-read, and a readahead of 64k
447 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
449 qemu-system-x86_64 -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on
452 Example: boot from an image stored on a VMware vSphere server with a self-signed
453 certificate using a local overlay for writes, a readahead of 64k and a timeout
456 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
458 qemu-system-x86_64 -drive file=/tmp/test.qcow2
466 @section Keys in the graphical frontends
470 During the graphical emulation, you can use special key combinations to change
471 modes. The default key mappings are shown below, but if you use @code{-alt-grab}
472 then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt) and if you use
473 @code{-ctrl-grab} then the modifier is the right Ctrl key (instead of Ctrl-Alt):
490 Restore the screen's un-scaled dimensions
494 Switch to virtual console 'n'. Standard console mappings are:
497 Target system display
506 Toggle mouse and keyboard grab.
512 @kindex Ctrl-PageDown
513 In the virtual consoles, you can use @key{Ctrl-Up}, @key{Ctrl-Down},
514 @key{Ctrl-PageUp} and @key{Ctrl-PageDown} to move in the back log.
519 @section Keys in the character backend multiplexer
523 During emulation, if you are using a character backend multiplexer
524 (which is the default if you are using @option{-nographic}) then
525 several commands are available via an escape sequence. These
526 key sequences all start with an escape character, which is @key{Ctrl-a}
527 by default, but can be changed with @option{-echr}. The list below assumes
528 you're using the default.
539 Save disk data back to file (if -snapshot)
542 Toggle console timestamps
545 Send break (magic sysrq in Linux)
548 Rotate between the frontends connected to the multiplexer (usually
549 this switches between the monitor and the console)
551 @kindex Ctrl-a Ctrl-a
552 Send the escape character to the frontend
559 The HTML documentation of QEMU for more precise information and Linux
560 user mode emulator invocation.
570 @section QEMU Monitor
573 The QEMU monitor is used to give complex commands to the QEMU
574 emulator. You can use it to:
579 Remove or insert removable media images
580 (such as CD-ROM or floppies).
583 Freeze/unfreeze the Virtual Machine (VM) and save or restore its state
586 @item Inspect the VM state without an external debugger.
592 The following commands are available:
594 @include qemu-monitor.texi
596 @include qemu-monitor-info.texi
598 @subsection Integer expressions
600 The monitor understands integers expressions for every integer
601 argument. You can use register names to get the value of specifics
602 CPU registers by prefixing them with @emph{$}.
607 QEMU supports many disk image formats, including growable disk images
608 (their size increase as non empty sectors are written), compressed and
609 encrypted disk images.
612 * disk_images_quickstart:: Quick start for disk image creation
613 * disk_images_snapshot_mode:: Snapshot mode
614 * vm_snapshots:: VM snapshots
615 * qemu_img_invocation:: qemu-img Invocation
616 * qemu_nbd_invocation:: qemu-nbd Invocation
617 * disk_images_formats:: Disk image file formats
618 * host_drives:: Using host drives
619 * disk_images_fat_images:: Virtual FAT disk images
620 * disk_images_nbd:: NBD access
621 * disk_images_sheepdog:: Sheepdog disk images
622 * disk_images_iscsi:: iSCSI LUNs
623 * disk_images_gluster:: GlusterFS disk images
624 * disk_images_ssh:: Secure Shell (ssh) disk images
625 * disk_images_nvme:: NVMe userspace driver
626 * disk_image_locking:: Disk image file locking
629 @node disk_images_quickstart
630 @subsection Quick start for disk image creation
632 You can create a disk image with the command:
634 qemu-img create myimage.img mysize
636 where @var{myimage.img} is the disk image filename and @var{mysize} is its
637 size in kilobytes. You can add an @code{M} suffix to give the size in
638 megabytes and a @code{G} suffix for gigabytes.
640 See @ref{qemu_img_invocation} for more information.
642 @node disk_images_snapshot_mode
643 @subsection Snapshot mode
645 If you use the option @option{-snapshot}, all disk images are
646 considered as read only. When sectors in written, they are written in
647 a temporary file created in @file{/tmp}. You can however force the
648 write back to the raw disk images by using the @code{commit} monitor
649 command (or @key{C-a s} in the serial console).
652 @subsection VM snapshots
654 VM snapshots are snapshots of the complete virtual machine including
655 CPU state, RAM, device state and the content of all the writable
656 disks. In order to use VM snapshots, you must have at least one non
657 removable and writable block device using the @code{qcow2} disk image
658 format. Normally this device is the first virtual hard drive.
660 Use the monitor command @code{savevm} to create a new VM snapshot or
661 replace an existing one. A human readable name can be assigned to each
662 snapshot in addition to its numerical ID.
664 Use @code{loadvm} to restore a VM snapshot and @code{delvm} to remove
665 a VM snapshot. @code{info snapshots} lists the available snapshots
666 with their associated information:
669 (qemu) info snapshots
670 Snapshot devices: hda
671 Snapshot list (from hda):
672 ID TAG VM SIZE DATE VM CLOCK
673 1 start 41M 2006-08-06 12:38:02 00:00:14.954
674 2 40M 2006-08-06 12:43:29 00:00:18.633
675 3 msys 40M 2006-08-06 12:44:04 00:00:23.514
678 A VM snapshot is made of a VM state info (its size is shown in
679 @code{info snapshots}) and a snapshot of every writable disk image.
680 The VM state info is stored in the first @code{qcow2} non removable
681 and writable block device. The disk image snapshots are stored in
682 every disk image. The size of a snapshot in a disk image is difficult
683 to evaluate and is not shown by @code{info snapshots} because the
684 associated disk sectors are shared among all the snapshots to save
685 disk space (otherwise each snapshot would need a full copy of all the
688 When using the (unrelated) @code{-snapshot} option
689 (@ref{disk_images_snapshot_mode}), you can always make VM snapshots,
690 but they are deleted as soon as you exit QEMU.
692 VM snapshots currently have the following known limitations:
695 They cannot cope with removable devices if they are removed or
696 inserted after a snapshot is done.
698 A few device drivers still have incomplete snapshot support so their
699 state is not saved or restored properly (in particular USB).
702 @node qemu_img_invocation
703 @subsection @code{qemu-img} Invocation
705 @include qemu-img.texi
707 @node qemu_nbd_invocation
708 @subsection @code{qemu-nbd} Invocation
710 @include qemu-nbd.texi
712 @include docs/qemu-block-drivers.texi
715 @section Network emulation
717 QEMU can simulate several network cards (e.g. PCI or ISA cards on the PC
718 target) and can connect them to a network backend on the host or an emulated
719 hub. The various host network backends can either be used to connect the NIC of
720 the guest to a real network (e.g. by using a TAP devices or the non-privileged
721 user mode network stack), or to other guest instances running in another QEMU
722 process (e.g. by using the socket host network backend).
724 @subsection Using TAP network interfaces
726 This is the standard way to connect QEMU to a real network. QEMU adds
727 a virtual network device on your host (called @code{tapN}), and you
728 can then configure it as if it was a real ethernet card.
730 @subsubsection Linux host
732 As an example, you can download the @file{linux-test-xxx.tar.gz}
733 archive and copy the script @file{qemu-ifup} in @file{/etc} and
734 configure properly @code{sudo} so that the command @code{ifconfig}
735 contained in @file{qemu-ifup} can be executed as root. You must verify
736 that your host kernel supports the TAP network interfaces: the
737 device @file{/dev/net/tun} must be present.
739 See @ref{sec_invocation} to have examples of command lines using the
740 TAP network interfaces.
742 @subsubsection Windows host
744 There is a virtual ethernet driver for Windows 2000/XP systems, called
745 TAP-Win32. But it is not included in standard QEMU for Windows,
746 so you will need to get it separately. It is part of OpenVPN package,
747 so download OpenVPN from : @url{https://openvpn.net/}.
749 @subsection Using the user mode network stack
751 By using the option @option{-net user} (default configuration if no
752 @option{-net} option is specified), QEMU uses a completely user mode
753 network stack (you don't need root privilege to use the virtual
754 network). The virtual network configuration is the following:
758 guest (10.0.2.15) <------> Firewall/DHCP server <-----> Internet
761 ----> DNS server (10.0.2.3)
763 ----> SMB server (10.0.2.4)
766 The QEMU VM behaves as if it was behind a firewall which blocks all
767 incoming connections. You can use a DHCP client to automatically
768 configure the network in the QEMU VM. The DHCP server assign addresses
769 to the hosts starting from 10.0.2.15.
771 In order to check that the user mode network is working, you can ping
772 the address 10.0.2.2 and verify that you got an address in the range
773 10.0.2.x from the QEMU virtual DHCP server.
775 Note that ICMP traffic in general does not work with user mode networking.
776 @code{ping}, aka. ICMP echo, to the local router (10.0.2.2) shall work,
777 however. If you're using QEMU on Linux >= 3.0, it can use unprivileged ICMP
778 ping sockets to allow @code{ping} to the Internet. The host admin has to set
779 the ping_group_range in order to grant access to those sockets. To allow ping
780 for GID 100 (usually users group):
783 echo 100 100 > /proc/sys/net/ipv4/ping_group_range
786 When using the built-in TFTP server, the router is also the TFTP
789 When using the @option{'-netdev user,hostfwd=...'} option, TCP or UDP
790 connections can be redirected from the host to the guest. It allows for
791 example to redirect X11, telnet or SSH connections.
795 QEMU can simulate several hubs. A hub can be thought of as a virtual connection
796 between several network devices. These devices can be for example QEMU virtual
797 ethernet cards or virtual Host ethernet devices (TAP devices). You can connect
798 guest NICs or host network backends to such a hub using the @option{-netdev
799 hubport} or @option{-nic hubport} options. The legacy @option{-net} option
800 also connects the given device to the emulated hub with ID 0 (i.e. the default
801 hub) unless you specify a netdev with @option{-net nic,netdev=xxx} here.
803 @subsection Connecting emulated networks between QEMU instances
805 Using the @option{-netdev socket} (or @option{-nic socket} or
806 @option{-net socket}) option, it is possible to create emulated
807 networks that span several QEMU instances.
808 See the description of the @option{-netdev socket} option in the
809 @ref{sec_invocation,,Invocation chapter} to have a basic example.
811 @node pcsys_other_devs
812 @section Other Devices
814 @subsection Inter-VM Shared Memory device
816 On Linux hosts, a shared memory device is available. The basic syntax
820 qemu-system-x86_64 -device ivshmem-plain,memdev=@var{hostmem}
823 where @var{hostmem} names a host memory backend. For a POSIX shared
824 memory backend, use something like
827 -object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=@var{hostmem}
830 If desired, interrupts can be sent between guest VMs accessing the same shared
831 memory region. Interrupt support requires using a shared memory server and
832 using a chardev socket to connect to it. The code for the shared memory server
833 is qemu.git/contrib/ivshmem-server. An example syntax when using the shared
837 # First start the ivshmem server once and for all
838 ivshmem-server -p @var{pidfile} -S @var{path} -m @var{shm-name} -l @var{shm-size} -n @var{vectors}
840 # Then start your qemu instances with matching arguments
841 qemu-system-x86_64 -device ivshmem-doorbell,vectors=@var{vectors},chardev=@var{id}
842 -chardev socket,path=@var{path},id=@var{id}
845 When using the server, the guest will be assigned a VM ID (>=0) that allows guests
846 using the same server to communicate via interrupts. Guests can read their
847 VM ID from a device register (see ivshmem-spec.txt).
849 @subsubsection Migration with ivshmem
851 With device property @option{master=on}, the guest will copy the shared
852 memory on migration to the destination host. With @option{master=off},
853 the guest will not be able to migrate with the device attached. In the
854 latter case, the device should be detached and then reattached after
855 migration using the PCI hotplug support.
857 At most one of the devices sharing the same memory can be master. The
858 master must complete migration before you plug back the other devices.
860 @subsubsection ivshmem and hugepages
862 Instead of specifying the <shm size> using POSIX shm, you may specify
863 a memory backend that has hugepage support:
866 qemu-system-x86_64 -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,id=mb1
867 -device ivshmem-plain,memdev=mb1
870 ivshmem-server also supports hugepages mount points with the
871 @option{-m} memory path argument.
873 @node direct_linux_boot
874 @section Direct Linux Boot
876 This section explains how to launch a Linux kernel inside QEMU without
877 having to make a full bootable image. It is very useful for fast Linux
882 qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"
885 Use @option{-kernel} to provide the Linux kernel image and
886 @option{-append} to give the kernel command line arguments. The
887 @option{-initrd} option can be used to provide an INITRD image.
889 When using the direct Linux boot, a disk image for the first hard disk
890 @file{hda} is required because its boot sector is used to launch the
893 If you do not need graphical output, you can disable it and redirect
894 the virtual serial port and the QEMU monitor to the console with the
895 @option{-nographic} option. The typical command line is:
897 qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
898 -append "root=/dev/hda console=ttyS0" -nographic
901 Use @key{Ctrl-a c} to switch between the serial console and the
902 monitor (@pxref{pcsys_keys}).
905 @section USB emulation
907 QEMU can emulate a PCI UHCI, OHCI, EHCI or XHCI USB controller. You can
908 plug virtual USB devices or real host USB devices (only works with certain
909 host operating systems). QEMU will automatically create and connect virtual
910 USB hubs as necessary to connect multiple USB devices.
917 @subsection Connecting USB devices
919 USB devices can be connected with the @option{-device usb-...} command line
920 option or the @code{device_add} monitor command. Available devices are:
924 Virtual Mouse. This will override the PS/2 mouse emulation when activated.
926 Pointer device that uses absolute coordinates (like a touchscreen).
927 This means QEMU is able to report the mouse position without having
928 to grab the mouse. Also overrides the PS/2 mouse emulation when activated.
929 @item usb-storage,drive=@var{drive_id}
930 Mass storage device backed by @var{drive_id} (@pxref{disk_images})
932 USB attached SCSI device, see
933 @url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
936 Bulk-only transport storage device, see
937 @url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt,usb-storage.txt}
938 for details here, too
939 @item usb-mtp,x-root=@var{dir}
940 Media transfer protocol device, using @var{dir} as root of the file tree
941 that is presented to the guest.
942 @item usb-host,hostbus=@var{bus},hostaddr=@var{addr}
943 Pass through the host device identified by @var{bus} and @var{addr}
944 @item usb-host,vendorid=@var{vendor},productid=@var{product}
945 Pass through the host device identified by @var{vendor} and @var{product} ID
946 @item usb-wacom-tablet
947 Virtual Wacom PenPartner tablet. This device is similar to the @code{tablet}
948 above but it can be used with the tslib library because in addition to touch
949 coordinates it reports touch pressure.
951 Standard USB keyboard. Will override the PS/2 keyboard (if present).
952 @item usb-serial,chardev=@var{id}
953 Serial converter. This emulates an FTDI FT232BM chip connected to host character
955 @item usb-braille,chardev=@var{id}
956 Braille device. This will use BrlAPI to display the braille output on a real
957 or fake device referenced by @var{id}.
958 @item usb-net[,netdev=@var{id}]
959 Network adapter that supports CDC ethernet and RNDIS protocols. @var{id}
960 specifies a netdev defined with @code{-netdev @dots{},id=@var{id}}.
961 For instance, user-mode networking can be used with
963 qemu-system-i386 [...] -netdev user,id=net0 -device usb-net,netdev=net0
966 Smartcard reader device
970 Bluetooth dongle for the transport layer of HCI. It is connected to HCI
971 scatternet 0 by default (corresponds to @code{-bt hci,vlan=0}).
972 Note that the syntax for the @code{-device usb-bt-dongle} option is not as
973 useful yet as it was with the legacy @code{-usbdevice} option. So to
974 configure an USB bluetooth device, you might need to use
975 "@code{-usbdevice bt}[:@var{hci-type}]" instead. This configures a
976 bluetooth dongle whose type is specified in the same format as with
977 the @option{-bt hci} option, @pxref{bt-hcis,,allowed HCI types}. If
978 no type is given, the HCI logic corresponds to @code{-bt hci,vlan=0}.
979 This USB device implements the USB Transport Layer of HCI. Example
982 @command{qemu-system-i386} [...@var{OPTIONS}...] @option{-usbdevice} bt:hci,vlan=3 @option{-bt} device:keyboard,vlan=3
986 @node host_usb_devices
987 @subsection Using host USB devices on a Linux host
989 WARNING: this is an experimental feature. QEMU will slow down when
990 using it. USB devices requiring real time streaming (i.e. USB Video
991 Cameras) are not supported yet.
994 @item If you use an early Linux 2.4 kernel, verify that no Linux driver
995 is actually using the USB device. A simple way to do that is simply to
996 disable the corresponding kernel module by renaming it from @file{mydriver.o}
997 to @file{mydriver.o.disabled}.
999 @item Verify that @file{/proc/bus/usb} is working (most Linux distributions should enable it by default). You should see something like that:
1005 @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:
1007 chown -R myuid /proc/bus/usb
1010 @item Launch QEMU and do in the monitor:
1013 Device 1.2, speed 480 Mb/s
1014 Class 00: USB device 1234:5678, USB DISK
1016 You should see the list of the devices you can use (Never try to use
1017 hubs, it won't work).
1019 @item Add the device in QEMU by using:
1021 device_add usb-host,vendorid=0x1234,productid=0x5678
1024 Normally the guest OS should report that a new USB device is plugged.
1025 You can use the option @option{-device usb-host,...} to do the same.
1027 @item Now you can try to use the host USB device in QEMU.
1031 When relaunching QEMU, you may have to unplug and plug again the USB
1032 device to make it work again (this is a bug).
1035 @section VNC security
1037 The VNC server capability provides access to the graphical console
1038 of the guest VM across the network. This has a number of security
1039 considerations depending on the deployment scenarios.
1043 * vnc_sec_password::
1044 * vnc_sec_certificate::
1045 * vnc_sec_certificate_verify::
1046 * vnc_sec_certificate_pw::
1048 * vnc_sec_certificate_sasl::
1052 @subsection Without passwords
1054 The simplest VNC server setup does not include any form of authentication.
1055 For this setup it is recommended to restrict it to listen on a UNIX domain
1056 socket only. For example
1059 qemu-system-i386 [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc
1062 This ensures that only users on local box with read/write access to that
1063 path can access the VNC server. To securely access the VNC server from a
1064 remote machine, a combination of netcat+ssh can be used to provide a secure
1067 @node vnc_sec_password
1068 @subsection With passwords
1070 The VNC protocol has limited support for password based authentication. Since
1071 the protocol limits passwords to 8 characters it should not be considered
1072 to provide high security. The password can be fairly easily brute-forced by
1073 a client making repeat connections. For this reason, a VNC server using password
1074 authentication should be restricted to only listen on the loopback interface
1075 or UNIX domain sockets. Password authentication is not supported when operating
1076 in FIPS 140-2 compliance mode as it requires the use of the DES cipher. Password
1077 authentication is requested with the @code{password} option, and then once QEMU
1078 is running the password is set with the monitor. Until the monitor is used to
1079 set the password all clients will be rejected.
1082 qemu-system-i386 [...OPTIONS...] -vnc :1,password -monitor stdio
1083 (qemu) change vnc password
1088 @node vnc_sec_certificate
1089 @subsection With x509 certificates
1091 The QEMU VNC server also implements the VeNCrypt extension allowing use of
1092 TLS for encryption of the session, and x509 certificates for authentication.
1093 The use of x509 certificates is strongly recommended, because TLS on its
1094 own is susceptible to man-in-the-middle attacks. Basic x509 certificate
1095 support provides a secure session, but no authentication. This allows any
1096 client to connect, and provides an encrypted session.
1099 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509=/etc/pki/qemu -monitor stdio
1102 In the above example @code{/etc/pki/qemu} should contain at least three files,
1103 @code{ca-cert.pem}, @code{server-cert.pem} and @code{server-key.pem}. Unprivileged
1104 users will want to use a private directory, for example @code{$HOME/.pki/qemu}.
1105 NB the @code{server-key.pem} file should be protected with file mode 0600 to
1106 only be readable by the user owning it.
1108 @node vnc_sec_certificate_verify
1109 @subsection With x509 certificates and client verification
1111 Certificates can also provide a means to authenticate the client connecting.
1112 The server will request that the client provide a certificate, which it will
1113 then validate against the CA certificate. This is a good choice if deploying
1114 in an environment with a private internal certificate authority.
1117 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509verify=/etc/pki/qemu -monitor stdio
1121 @node vnc_sec_certificate_pw
1122 @subsection With x509 certificates, client verification and passwords
1124 Finally, the previous method can be combined with VNC password authentication
1125 to provide two layers of authentication for clients.
1128 qemu-system-i386 [...OPTIONS...] -vnc :1,password,tls,x509verify=/etc/pki/qemu -monitor stdio
1129 (qemu) change vnc password
1136 @subsection With SASL authentication
1138 The SASL authentication method is a VNC extension, that provides an
1139 easily extendable, pluggable authentication method. This allows for
1140 integration with a wide range of authentication mechanisms, such as
1141 PAM, GSSAPI/Kerberos, LDAP, SQL databases, one-time keys and more.
1142 The strength of the authentication depends on the exact mechanism
1143 configured. If the chosen mechanism also provides a SSF layer, then
1144 it will encrypt the datastream as well.
1146 Refer to the later docs on how to choose the exact SASL mechanism
1147 used for authentication, but assuming use of one supporting SSF,
1148 then QEMU can be launched with:
1151 qemu-system-i386 [...OPTIONS...] -vnc :1,sasl -monitor stdio
1154 @node vnc_sec_certificate_sasl
1155 @subsection With x509 certificates and SASL authentication
1157 If the desired SASL authentication mechanism does not supported
1158 SSF layers, then it is strongly advised to run it in combination
1159 with TLS and x509 certificates. This provides securely encrypted
1160 data stream, avoiding risk of compromising of the security
1161 credentials. This can be enabled, by combining the 'sasl' option
1162 with the aforementioned TLS + x509 options:
1165 qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509,sasl -monitor stdio
1168 @node vnc_setup_sasl
1170 @subsection Configuring SASL mechanisms
1172 The following documentation assumes use of the Cyrus SASL implementation on a
1173 Linux host, but the principles should apply to any other SASL implementation
1174 or host. When SASL is enabled, the mechanism configuration will be loaded from
1175 system default SASL service config /etc/sasl2/qemu.conf. If running QEMU as an
1176 unprivileged user, an environment variable SASL_CONF_PATH can be used to make
1177 it search alternate locations for the service config file.
1179 If the TLS option is enabled for VNC, then it will provide session encryption,
1180 otherwise the SASL mechanism will have to provide encryption. In the latter
1181 case the list of possible plugins that can be used is drastically reduced. In
1182 fact only the GSSAPI SASL mechanism provides an acceptable level of security
1183 by modern standards. Previous versions of QEMU referred to the DIGEST-MD5
1184 mechanism, however, it has multiple serious flaws described in detail in
1185 RFC 6331 and thus should never be used any more. The SCRAM-SHA-1 mechanism
1186 provides a simple username/password auth facility similar to DIGEST-MD5, but
1187 does not support session encryption, so can only be used in combination with
1190 When not using TLS the recommended configuration is
1194 keytab: /etc/qemu/krb5.tab
1197 This says to use the 'GSSAPI' mechanism with the Kerberos v5 protocol, with
1198 the server principal stored in /etc/qemu/krb5.tab. For this to work the
1199 administrator of your KDC must generate a Kerberos principal for the server,
1200 with a name of 'qemu/somehost.example.com@@EXAMPLE.COM' replacing
1201 'somehost.example.com' with the fully qualified host name of the machine
1202 running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm.
1204 When using TLS, if username+password authentication is desired, then a
1205 reasonable configuration is
1208 mech_list: scram-sha-1
1209 sasldb_path: /etc/qemu/passwd.db
1212 The @code{saslpasswd2} program can be used to populate the @code{passwd.db}
1215 Other SASL configurations will be left as an exercise for the reader. Note that
1216 all mechanisms, except GSSAPI, should be combined with use of TLS to ensure a
1217 secure data channel.
1221 @section TLS setup for network services
1223 Almost all network services in QEMU have the ability to use TLS for
1224 session data encryption, along with x509 certificates for simple
1225 client authentication. What follows is a description of how to
1226 generate certificates suitable for usage with QEMU, and applies to
1227 the VNC server, character devices with the TCP backend, NBD server
1228 and client, and migration server and client.
1230 At a high level, QEMU requires certificates and private keys to be
1231 provided in PEM format. Aside from the core fields, the certificates
1232 should include various extension data sets, including v3 basic
1233 constraints data, key purpose, key usage and subject alt name.
1235 The GnuTLS package includes a command called @code{certtool} which can
1236 be used to easily generate certificates and keys in the required format
1237 with expected data present. Alternatively a certificate management
1238 service may be used.
1240 At a minimum it is necessary to setup a certificate authority, and
1241 issue certificates to each server. If using x509 certificates for
1242 authentication, then each client will also need to be issued a
1245 Assuming that the QEMU network services will only ever be exposed to
1246 clients on a private intranet, there is no need to use a commercial
1247 certificate authority to create certificates. A self-signed CA is
1248 sufficient, and in fact likely to be more secure since it removes
1249 the ability of malicious 3rd parties to trick the CA into mis-issuing
1250 certs for impersonating your services. The only likely exception
1251 where a commercial CA might be desirable is if enabling the VNC
1252 websockets server and exposing it directly to remote browser clients.
1253 In such a case it might be useful to use a commercial CA to avoid
1254 needing to install custom CA certs in the web browsers.
1256 The recommendation is for the server to keep its certificates in either
1257 @code{/etc/pki/qemu} or for unprivileged users in @code{$HOME/.pki/qemu}.
1261 * tls_generate_server::
1262 * tls_generate_client::
1265 @node tls_generate_ca
1266 @subsection Setup the Certificate Authority
1268 This step only needs to be performed once per organization / organizational
1269 unit. First the CA needs a private key. This key must be kept VERY secret
1270 and secure. If this key is compromised the entire trust chain of the certificates
1271 issued with it is lost.
1274 # certtool --generate-privkey > ca-key.pem
1277 To generate a self-signed certificate requires one core piece of information,
1278 the name of the organization. A template file @code{ca.info} should be
1279 populated with the desired data to avoid having to deal with interactive
1280 prompts from certtool:
1282 # cat > ca.info <<EOF
1283 cn = Name of your organization
1287 # certtool --generate-self-signed \
1288 --load-privkey ca-key.pem
1289 --template ca.info \
1290 --outfile ca-cert.pem
1293 The @code{ca} keyword in the template sets the v3 basic constraints extension
1294 to indicate this certificate is for a CA, while @code{cert_signing_key} sets
1295 the key usage extension to indicate this will be used for signing other keys.
1296 The generated @code{ca-cert.pem} file should be copied to all servers and
1297 clients wishing to utilize TLS support in the VNC server. The @code{ca-key.pem}
1298 must not be disclosed/copied anywhere except the host responsible for issuing
1301 @node tls_generate_server
1302 @subsection Issuing server certificates
1304 Each server (or host) needs to be issued with a key and certificate. When connecting
1305 the certificate is sent to the client which validates it against the CA certificate.
1306 The core pieces of information for a server certificate are the hostnames and/or IP
1307 addresses that will be used by clients when connecting. The hostname / IP address
1308 that the client specifies when connecting will be validated against the hostname(s)
1309 and IP address(es) recorded in the server certificate, and if no match is found
1310 the client will close the connection.
1312 Thus it is recommended that the server certificate include both the fully qualified
1313 and unqualified hostnames. If the server will have permanently assigned IP address(es),
1314 and clients are likely to use them when connecting, they may also be included in the
1315 certificate. Both IPv4 and IPv6 addresses are supported. Historically certificates
1316 only included 1 hostname in the @code{CN} field, however, usage of this field for
1317 validation is now deprecated. Instead modern TLS clients will validate against the
1318 Subject Alt Name extension data, which allows for multiple entries. In the future
1319 usage of the @code{CN} field may be discontinued entirely, so providing SAN
1320 extension data is strongly recommended.
1322 On the host holding the CA, create template files containing the information
1323 for each server, and use it to issue server certificates.
1326 # cat > server-hostNNN.info <<EOF
1327 organization = Name of your organization
1328 cn = hostNNN.foo.example.com
1330 dns_name = hostNNN.foo.example.com
1331 ip_address = 10.0.1.87
1332 ip_address = 192.8.0.92
1333 ip_address = 2620:0:cafe::87
1334 ip_address = 2001:24::92
1339 # certtool --generate-privkey > server-hostNNN-key.pem
1340 # certtool --generate-certificate \
1341 --load-ca-certificate ca-cert.pem \
1342 --load-ca-privkey ca-key.pem \
1343 --load-privkey server-hostNNN-key.pem \
1344 --template server-hostNNN.info \
1345 --outfile server-hostNNN-cert.pem
1348 The @code{dns_name} and @code{ip_address} fields in the template are setting
1349 the subject alt name extension data. The @code{tls_www_server} keyword is the
1350 key purpose extension to indicate this certificate is intended for usage in
1351 a web server. Although QEMU network services are not in fact HTTP servers
1352 (except for VNC websockets), setting this key purpose is still recommended.
1353 The @code{encryption_key} and @code{signing_key} keyword is the key usage
1354 extension to indicate this certificate is intended for usage in the data
1357 The @code{server-hostNNN-key.pem} and @code{server-hostNNN-cert.pem} files
1358 should now be securely copied to the server for which they were generated,
1359 and renamed to @code{server-key.pem} and @code{server-cert.pem} when added
1360 to the @code{/etc/pki/qemu} directory on the target host. The @code{server-key.pem}
1361 file is security sensitive and should be kept protected with file mode 0600
1362 to prevent disclosure.
1364 @node tls_generate_client
1365 @subsection Issuing client certificates
1367 The QEMU x509 TLS credential setup defaults to enabling client verification
1368 using certificates, providing a simple authentication mechanism. If this
1369 default is used, each client also needs to be issued a certificate. The client
1370 certificate contains enough metadata to uniquely identify the client with the
1371 scope of the certificate authority. The client certificate would typically
1372 include fields for organization, state, city, building, etc.
1374 Once again on the host holding the CA, create template files containing the
1375 information for each client, and use it to issue client certificates.
1379 # cat > client-hostNNN.info <<EOF
1382 locality = City Of London
1383 organization = Name of your organization
1384 cn = hostNNN.foo.example.com
1389 # certtool --generate-privkey > client-hostNNN-key.pem
1390 # certtool --generate-certificate \
1391 --load-ca-certificate ca-cert.pem \
1392 --load-ca-privkey ca-key.pem \
1393 --load-privkey client-hostNNN-key.pem \
1394 --template client-hostNNN.info \
1395 --outfile client-hostNNN-cert.pem
1398 The subject alt name extension data is not required for clients, so the
1399 the @code{dns_name} and @code{ip_address} fields are not included.
1400 The @code{tls_www_client} keyword is the key purpose extension to indicate
1401 this certificate is intended for usage in a web client. Although QEMU
1402 network clients are not in fact HTTP clients, setting this key purpose is
1403 still recommended. The @code{encryption_key} and @code{signing_key} keyword
1404 is the key usage extension to indicate this certificate is intended for
1405 usage in the data session.
1407 The @code{client-hostNNN-key.pem} and @code{client-hostNNN-cert.pem} files
1408 should now be securely copied to the client for which they were generated,
1409 and renamed to @code{client-key.pem} and @code{client-cert.pem} when added
1410 to the @code{/etc/pki/qemu} directory on the target host. The @code{client-key.pem}
1411 file is security sensitive and should be kept protected with file mode 0600
1412 to prevent disclosure.
1414 If a single host is going to be using TLS in both a client and server
1415 role, it is possible to create a single certificate to cover both roles.
1416 This would be quite common for the migration and NBD services, where a
1417 QEMU process will be started by accepting a TLS protected incoming migration,
1418 and later itself be migrated out to another host. To generate a single
1419 certificate, simply include the template data from both the client and server
1420 instructions in one.
1423 # cat > both-hostNNN.info <<EOF
1426 locality = City Of London
1427 organization = Name of your organization
1428 cn = hostNNN.foo.example.com
1430 dns_name = hostNNN.foo.example.com
1431 ip_address = 10.0.1.87
1432 ip_address = 192.8.0.92
1433 ip_address = 2620:0:cafe::87
1434 ip_address = 2001:24::92
1440 # certtool --generate-privkey > both-hostNNN-key.pem
1441 # certtool --generate-certificate \
1442 --load-ca-certificate ca-cert.pem \
1443 --load-ca-privkey ca-key.pem \
1444 --load-privkey both-hostNNN-key.pem \
1445 --template both-hostNNN.info \
1446 --outfile both-hostNNN-cert.pem
1449 When copying the PEM files to the target host, save them twice,
1450 once as @code{server-cert.pem} and @code{server-key.pem}, and
1451 again as @code{client-cert.pem} and @code{client-key.pem}.
1453 @node tls_creds_setup
1454 @subsection TLS x509 credential configuration
1456 QEMU has a standard mechanism for loading x509 credentials that will be
1457 used for network services and clients. It requires specifying the
1458 @code{tls-creds-x509} class name to the @code{--object} command line
1459 argument for the system emulators. Each set of credentials loaded should
1460 be given a unique string identifier via the @code{id} parameter. A single
1461 set of TLS credentials can be used for multiple network backends, so VNC,
1462 migration, NBD, character devices can all share the same credentials. Note,
1463 however, that credentials for use in a client endpoint must be loaded
1464 separately from those used in a server endpoint.
1466 When specifying the object, the @code{dir} parameters specifies which
1467 directory contains the credential files. This directory is expected to
1468 contain files with the names mentioned previously, @code{ca-cert.pem},
1469 @code{server-key.pem}, @code{server-cert.pem}, @code{client-key.pem}
1470 and @code{client-cert.pem} as appropriate. It is also possible to
1471 include a set of pre-generated Diffie-Hellman (DH) parameters in a file
1472 @code{dh-params.pem}, which can be created using the
1473 @code{certtool --generate-dh-params} command. If omitted, QEMU will
1474 dynamically generate DH parameters when loading the credentials.
1476 The @code{endpoint} parameter indicates whether the credentials will
1477 be used for a network client or server, and determines which PEM
1480 The @code{verify} parameter determines whether x509 certificate
1481 validation should be performed. This defaults to enabled, meaning
1482 clients will always validate the server hostname against the
1483 certificate subject alt name fields and/or CN field. It also
1484 means that servers will request that clients provide a certificate
1485 and validate them. Verification should never be turned off for
1486 client endpoints, however, it may be turned off for server endpoints
1487 if an alternative mechanism is used to authenticate clients. For
1488 example, the VNC server can use SASL to authenticate clients
1491 To load server credentials with client certificate validation
1495 $QEMU -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server
1498 while to load client credentials use
1501 $QEMU -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=client
1504 Network services which support TLS will all have a @code{tls-creds}
1505 parameter which expects the ID of the TLS credentials object. For
1509 $QEMU -vnc 0.0.0.0:0,tls-creds=tls0
1515 QEMU has a primitive support to work with gdb, so that you can do
1516 'Ctrl-C' while the virtual machine is running and inspect its state.
1518 In order to use gdb, launch QEMU with the '-s' option. It will wait for a
1521 qemu-system-i386 -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
1522 -append "root=/dev/hda"
1523 Connected to host network interface: tun0
1524 Waiting gdb connection on port 1234
1527 Then launch gdb on the 'vmlinux' executable:
1532 In gdb, connect to QEMU:
1534 (gdb) target remote localhost:1234
1537 Then you can use gdb normally. For example, type 'c' to launch the kernel:
1542 Here are some useful tips in order to use gdb on system code:
1546 Use @code{info reg} to display all the CPU registers.
1548 Use @code{x/10i $eip} to display the code at the PC position.
1550 Use @code{set architecture i8086} to dump 16 bit code. Then use
1551 @code{x/10i $cs*16+$eip} to dump the code at the PC position.
1554 Advanced debugging options:
1556 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:
1558 @item maintenance packet qqemu.sstepbits
1560 This will display the MASK bits used to control the single stepping IE:
1562 (gdb) maintenance packet qqemu.sstepbits
1563 sending: "qqemu.sstepbits"
1564 received: "ENABLE=1,NOIRQ=2,NOTIMER=4"
1566 @item maintenance packet qqemu.sstep
1568 This will display the current value of the mask used when single stepping IE:
1570 (gdb) maintenance packet qqemu.sstep
1571 sending: "qqemu.sstep"
1574 @item maintenance packet Qqemu.sstep=HEX_VALUE
1576 This will change the single step mask, so if wanted to enable IRQs on the single step, but not timers, you would use:
1578 (gdb) maintenance packet Qqemu.sstep=0x5
1579 sending: "qemu.sstep=0x5"
1584 @node pcsys_os_specific
1585 @section Target OS specific information
1589 To have access to SVGA graphic modes under X11, use the @code{vesa} or
1590 the @code{cirrus} X11 driver. For optimal performances, use 16 bit
1591 color depth in the guest and the host OS.
1593 When using a 2.6 guest Linux kernel, you should add the option
1594 @code{clock=pit} on the kernel command line because the 2.6 Linux
1595 kernels make very strict real time clock checks by default that QEMU
1596 cannot simulate exactly.
1598 When using a 2.6 guest Linux kernel, verify that the 4G/4G patch is
1599 not activated because QEMU is slower with this patch. The QEMU
1600 Accelerator Module is also much slower in this case. Earlier Fedora
1601 Core 3 Linux kernel (< 2.6.9-1.724_FC3) were known to incorporate this
1602 patch by default. Newer kernels don't have it.
1606 If you have a slow host, using Windows 95 is better as it gives the
1607 best speed. Windows 2000 is also a good choice.
1609 @subsubsection SVGA graphic modes support
1611 QEMU emulates a Cirrus Logic GD5446 Video
1612 card. All Windows versions starting from Windows 95 should recognize
1613 and use this graphic card. For optimal performances, use 16 bit color
1614 depth in the guest and the host OS.
1616 If you are using Windows XP as guest OS and if you want to use high
1617 resolution modes which the Cirrus Logic BIOS does not support (i.e. >=
1618 1280x1024x16), then you should use the VESA VBE virtual graphic card
1619 (option @option{-std-vga}).
1621 @subsubsection CPU usage reduction
1623 Windows 9x does not correctly use the CPU HLT
1624 instruction. The result is that it takes host CPU cycles even when
1625 idle. You can install the utility from
1626 @url{https://web.archive.org/web/20060212132151/http://www.user.cityline.ru/~maxamn/amnhltm.zip}
1627 to solve this problem. Note that no such tool is needed for NT, 2000 or XP.
1629 @subsubsection Windows 2000 disk full problem
1631 Windows 2000 has a bug which gives a disk full problem during its
1632 installation. When installing it, use the @option{-win2k-hack} QEMU
1633 option to enable a specific workaround. After Windows 2000 is
1634 installed, you no longer need this option (this option slows down the
1637 @subsubsection Windows 2000 shutdown
1639 Windows 2000 cannot automatically shutdown in QEMU although Windows 98
1640 can. It comes from the fact that Windows 2000 does not automatically
1641 use the APM driver provided by the BIOS.
1643 In order to correct that, do the following (thanks to Struan
1644 Bartlett): go to the Control Panel => Add/Remove Hardware & Next =>
1645 Add/Troubleshoot a device => Add a new device & Next => No, select the
1646 hardware from a list & Next => NT Apm/Legacy Support & Next => Next
1647 (again) a few times. Now the driver is installed and Windows 2000 now
1648 correctly instructs QEMU to shutdown at the appropriate moment.
1650 @subsubsection Share a directory between Unix and Windows
1652 See @ref{sec_invocation} about the help of the option
1653 @option{'-netdev user,smb=...'}.
1655 @subsubsection Windows XP security problem
1657 Some releases of Windows XP install correctly but give a security
1660 A problem is preventing Windows from accurately checking the
1661 license for this computer. Error code: 0x800703e6.
1664 The workaround is to install a service pack for XP after a boot in safe
1665 mode. Then reboot, and the problem should go away. Since there is no
1666 network while in safe mode, its recommended to download the full
1667 installation of SP1 or SP2 and transfer that via an ISO or using the
1668 vvfat block device ("-hdb fat:directory_which_holds_the_SP").
1670 @subsection MS-DOS and FreeDOS
1672 @subsubsection CPU usage reduction
1674 DOS does not correctly use the CPU HLT instruction. The result is that
1675 it takes host CPU cycles even when idle. You can install the utility from
1676 @url{https://web.archive.org/web/20051222085335/http://www.vmware.com/software/dosidle210.zip}
1677 to solve this problem.
1679 @node QEMU System emulator for non PC targets
1680 @chapter QEMU System emulator for non PC targets
1682 QEMU is a generic emulator and it emulates many non PC
1683 machines. Most of the options are similar to the PC emulator. The
1684 differences are mentioned in the following sections.
1687 * PowerPC System emulator::
1688 * Sparc32 System emulator::
1689 * Sparc64 System emulator::
1690 * MIPS System emulator::
1691 * ARM System emulator::
1692 * ColdFire System emulator::
1693 * Cris System emulator::
1694 * Microblaze System emulator::
1695 * SH4 System emulator::
1696 * Xtensa System emulator::
1699 @node PowerPC System emulator
1700 @section PowerPC System emulator
1701 @cindex system emulation (PowerPC)
1703 Use the executable @file{qemu-system-ppc} to simulate a complete PREP
1704 or PowerMac PowerPC system.
1706 QEMU emulates the following PowerMac peripherals:
1710 UniNorth or Grackle PCI Bridge
1712 PCI VGA compatible card with VESA Bochs Extensions
1714 2 PMAC IDE interfaces with hard disk and CD-ROM support
1720 VIA-CUDA with ADB keyboard and mouse.
1723 QEMU emulates the following PREP peripherals:
1729 PCI VGA compatible card with VESA Bochs Extensions
1731 2 IDE interfaces with hard disk and CD-ROM support
1735 NE2000 network adapters
1739 PREP Non Volatile RAM
1741 PC compatible keyboard and mouse.
1744 QEMU uses the Open Hack'Ware Open Firmware Compatible BIOS available at
1745 @url{http://perso.magic.fr/l_indien/OpenHackWare/index.htm}.
1747 Since version 0.9.1, QEMU uses OpenBIOS @url{https://www.openbios.org/}
1748 for the g3beige and mac99 PowerMac machines. OpenBIOS is a free (GPL
1749 v2) portable firmware implementation. The goal is to implement a 100%
1750 IEEE 1275-1994 (referred to as Open Firmware) compliant firmware.
1752 @c man begin OPTIONS
1754 The following options are specific to the PowerPC emulation:
1758 @item -g @var{W}x@var{H}[x@var{DEPTH}]
1760 Set the initial VGA graphic mode. The default is 800x600x32.
1762 @item -prom-env @var{string}
1764 Set OpenBIOS variables in NVRAM, for example:
1767 qemu-system-ppc -prom-env 'auto-boot?=false' \
1768 -prom-env 'boot-device=hd:2,\yaboot' \
1769 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
1772 These variables are not used by Open Hack'Ware.
1779 More information is available at
1780 @url{http://perso.magic.fr/l_indien/qemu-ppc/}.
1782 @node Sparc32 System emulator
1783 @section Sparc32 System emulator
1784 @cindex system emulation (Sparc32)
1786 Use the executable @file{qemu-system-sparc} to simulate the following
1787 Sun4m architecture machines:
1802 SPARCstation Voyager
1809 The emulation is somewhat complete. SMP up to 16 CPUs is supported,
1810 but Linux limits the number of usable CPUs to 4.
1812 QEMU emulates the following sun4m peripherals:
1818 TCX or cgthree Frame buffer
1820 Lance (Am7990) Ethernet
1822 Non Volatile RAM M48T02/M48T08
1824 Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboard
1825 and power/reset logic
1827 ESP SCSI controller with hard disk and CD-ROM support
1829 Floppy drive (not on SS-600MP)
1831 CS4231 sound device (only on SS-5, not working yet)
1834 The number of peripherals is fixed in the architecture. Maximum
1835 memory size depends on the machine type, for SS-5 it is 256MB and for
1838 Since version 0.8.2, QEMU uses OpenBIOS
1839 @url{https://www.openbios.org/}. OpenBIOS is a free (GPL v2) portable
1840 firmware implementation. The goal is to implement a 100% IEEE
1841 1275-1994 (referred to as Open Firmware) compliant firmware.
1843 A sample Linux 2.6 series kernel and ram disk image are available on
1844 the QEMU web site. There are still issues with NetBSD and OpenBSD, but
1845 most kernel versions work. Please note that currently older Solaris kernels
1846 don't work probably due to interface issues between OpenBIOS and
1849 @c man begin OPTIONS
1851 The following options are specific to the Sparc32 emulation:
1855 @item -g @var{W}x@var{H}x[x@var{DEPTH}]
1857 Set the initial graphics mode. For TCX, the default is 1024x768x8 with the
1858 option of 1024x768x24. For cgthree, the default is 1024x768x8 with the option
1859 of 1152x900x8 for people who wish to use OBP.
1861 @item -prom-env @var{string}
1863 Set OpenBIOS variables in NVRAM, for example:
1866 qemu-system-sparc -prom-env 'auto-boot?=false' \
1867 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
1870 @item -M [SS-4|SS-5|SS-10|SS-20|SS-600MP|LX|Voyager|SPARCClassic] [|SPARCbook]
1872 Set the emulated machine type. Default is SS-5.
1878 @node Sparc64 System emulator
1879 @section Sparc64 System emulator
1880 @cindex system emulation (Sparc64)
1882 Use the executable @file{qemu-system-sparc64} to simulate a Sun4u
1883 (UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic
1884 Niagara (T1) machine. The Sun4u emulator is mostly complete, being
1885 able to run Linux, NetBSD and OpenBSD in headless (-nographic) mode. The
1886 Sun4v emulator is still a work in progress.
1888 The Niagara T1 emulator makes use of firmware and OS binaries supplied in the S10image/ directory
1889 of the OpenSPARC T1 project @url{http://download.oracle.com/technetwork/systems/opensparc/OpenSPARCT1_Arch.1.5.tar.bz2}
1890 and is able to boot the disk.s10hw2 Solaris image.
1892 qemu-system-sparc64 -M niagara -L /path-to/S10image/ \
1894 -drive if=pflash,readonly=on,file=/S10image/disk.s10hw2
1898 QEMU emulates the following peripherals:
1902 UltraSparc IIi APB PCI Bridge
1904 PCI VGA compatible card with VESA Bochs Extensions
1906 PS/2 mouse and keyboard
1908 Non Volatile RAM M48T59
1910 PC-compatible serial ports
1912 2 PCI IDE interfaces with hard disk and CD-ROM support
1917 @c man begin OPTIONS
1919 The following options are specific to the Sparc64 emulation:
1923 @item -prom-env @var{string}
1925 Set OpenBIOS variables in NVRAM, for example:
1928 qemu-system-sparc64 -prom-env 'auto-boot?=false'
1931 @item -M [sun4u|sun4v|niagara]
1933 Set the emulated machine type. The default is sun4u.
1939 @node MIPS System emulator
1940 @section MIPS System emulator
1941 @cindex system emulation (MIPS)
1943 Four executables cover simulation of 32 and 64-bit MIPS systems in
1944 both endian options, @file{qemu-system-mips}, @file{qemu-system-mipsel}
1945 @file{qemu-system-mips64} and @file{qemu-system-mips64el}.
1946 Five different machine types are emulated:
1950 A generic ISA PC-like machine "mips"
1952 The MIPS Malta prototype board "malta"
1954 An ACER Pica "pica61". This machine needs the 64-bit emulator.
1956 MIPS emulator pseudo board "mipssim"
1958 A MIPS Magnum R4000 machine "magnum". This machine needs the 64-bit emulator.
1961 The generic emulation is supported by Debian 'Etch' and is able to
1962 install Debian into a virtual disk image. The following devices are
1967 A range of MIPS CPUs, default is the 24Kf
1969 PC style serial port
1976 The Malta emulation supports the following devices:
1980 Core board with MIPS 24Kf CPU and Galileo system controller
1982 PIIX4 PCI/USB/SMbus controller
1984 The Multi-I/O chip's serial device
1986 PCI network cards (PCnet32 and others)
1988 Malta FPGA serial device
1990 Cirrus (default) or any other PCI VGA graphics card
1993 The ACER Pica emulation supports:
1999 PC-style IRQ and DMA controllers
2006 The mipssim pseudo board emulation provides an environment similar
2007 to what the proprietary MIPS emulator uses for running Linux.
2012 A range of MIPS CPUs, default is the 24Kf
2014 PC style serial port
2016 MIPSnet network emulation
2019 The MIPS Magnum R4000 emulation supports:
2025 PC-style IRQ controller
2035 @node ARM System emulator
2036 @section ARM System emulator
2037 @cindex system emulation (ARM)
2039 Use the executable @file{qemu-system-arm} to simulate a ARM
2040 machine. The ARM Integrator/CP board is emulated with the following
2045 ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
2049 SMC 91c111 Ethernet adapter
2051 PL110 LCD controller
2053 PL050 KMI with PS/2 keyboard and mouse.
2055 PL181 MultiMedia Card Interface with SD card.
2058 The ARM Versatile baseboard is emulated with the following devices:
2062 ARM926E, ARM1136 or Cortex-A8 CPU
2064 PL190 Vectored Interrupt Controller
2068 SMC 91c111 Ethernet adapter
2070 PL110 LCD controller
2072 PL050 KMI with PS/2 keyboard and mouse.
2074 PCI host bridge. Note the emulated PCI bridge only provides access to
2075 PCI memory space. It does not provide access to PCI IO space.
2076 This means some devices (eg. ne2k_pci NIC) are not usable, and others
2077 (eg. rtl8139 NIC) are only usable when the guest drivers use the memory
2078 mapped control registers.
2080 PCI OHCI USB controller.
2082 LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices.
2084 PL181 MultiMedia Card Interface with SD card.
2087 Several variants of the ARM RealView baseboard are emulated,
2088 including the EB, PB-A8 and PBX-A9. Due to interactions with the
2089 bootloader, only certain Linux kernel configurations work out
2090 of the box on these boards.
2092 Kernels for the PB-A8 board should have CONFIG_REALVIEW_HIGH_PHYS_OFFSET
2093 enabled in the kernel, and expect 512M RAM. Kernels for The PBX-A9 board
2094 should have CONFIG_SPARSEMEM enabled, CONFIG_REALVIEW_HIGH_PHYS_OFFSET
2095 disabled and expect 1024M RAM.
2097 The following devices are emulated:
2101 ARM926E, ARM1136, ARM11MPCore, Cortex-A8 or Cortex-A9 MPCore CPU
2103 ARM AMBA Generic/Distributed Interrupt Controller
2107 SMC 91c111 or SMSC LAN9118 Ethernet adapter
2109 PL110 LCD controller
2111 PL050 KMI with PS/2 keyboard and mouse
2115 PCI OHCI USB controller
2117 LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices
2119 PL181 MultiMedia Card Interface with SD card.
2122 The XScale-based clamshell PDA models ("Spitz", "Akita", "Borzoi"
2123 and "Terrier") emulation includes the following peripherals:
2127 Intel PXA270 System-on-chip (ARM V5TE core)
2131 IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in "Akita"
2133 On-chip OHCI USB controller
2135 On-chip LCD controller
2137 On-chip Real Time Clock
2139 TI ADS7846 touchscreen controller on SSP bus
2141 Maxim MAX1111 analog-digital converter on I@math{^2}C bus
2143 GPIO-connected keyboard controller and LEDs
2145 Secure Digital card connected to PXA MMC/SD host
2149 WM8750 audio CODEC on I@math{^2}C and I@math{^2}S busses
2152 The Palm Tungsten|E PDA (codename "Cheetah") emulation includes the
2157 Texas Instruments OMAP310 System-on-chip (ARM 925T core)
2159 ROM and RAM memories (ROM firmware image can be loaded with -option-rom)
2161 On-chip LCD controller
2163 On-chip Real Time Clock
2165 TI TSC2102i touchscreen controller / analog-digital converter / Audio
2166 CODEC, connected through MicroWire and I@math{^2}S busses
2168 GPIO-connected matrix keypad
2170 Secure Digital card connected to OMAP MMC/SD host
2175 Nokia N800 and N810 internet tablets (known also as RX-34 and RX-44 / 48)
2176 emulation supports the following elements:
2180 Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)
2182 RAM and non-volatile OneNAND Flash memories
2184 Display connected to EPSON remote framebuffer chip and OMAP on-chip
2185 display controller and a LS041y3 MIPI DBI-C controller
2187 TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen controllers
2188 driven through SPI bus
2190 National Semiconductor LM8323-controlled qwerty keyboard driven
2191 through I@math{^2}C bus
2193 Secure Digital card connected to OMAP MMC/SD host
2195 Three OMAP on-chip UARTs and on-chip STI debugging console
2197 A Bluetooth(R) transceiver and HCI connected to an UART
2199 Mentor Graphics "Inventra" dual-role USB controller embedded in a TI
2200 TUSB6010 chip - only USB host mode is supported
2202 TI TMP105 temperature sensor driven through I@math{^2}C bus
2204 TI TWL92230C power management companion with an RTC on I@math{^2}C bus
2206 Nokia RETU and TAHVO multi-purpose chips with an RTC, connected
2210 The Luminary Micro Stellaris LM3S811EVB emulation includes the following
2217 64k Flash and 8k SRAM.
2219 Timers, UARTs, ADC and I@math{^2}C interface.
2221 OSRAM Pictiva 96x16 OLED with SSD0303 controller on I@math{^2}C bus.
2224 The Luminary Micro Stellaris LM3S6965EVB emulation includes the following
2231 256k Flash and 64k SRAM.
2233 Timers, UARTs, ADC, I@math{^2}C and SSI interfaces.
2235 OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via SSI.
2238 The Freecom MusicPal internet radio emulation includes the following
2243 Marvell MV88W8618 ARM core.
2245 32 MB RAM, 256 KB SRAM, 8 MB flash.
2249 MV88W8xx8 Ethernet controller
2251 MV88W8618 audio controller, WM8750 CODEC and mixer
2253 128×64 display with brightness control
2255 2 buttons, 2 navigation wheels with button function
2258 The Siemens SX1 models v1 and v2 (default) basic emulation.
2259 The emulation includes the following elements:
2263 Texas Instruments OMAP310 System-on-chip (ARM 925T core)
2265 ROM and RAM memories (ROM firmware image can be loaded with -pflash)
2267 1 Flash of 16MB and 1 Flash of 8MB
2271 On-chip LCD controller
2273 On-chip Real Time Clock
2275 Secure Digital card connected to OMAP MMC/SD host
2280 A Linux 2.6 test image is available on the QEMU web site. More
2281 information is available in the QEMU mailing-list archive.
2283 @c man begin OPTIONS
2285 The following options are specific to the ARM emulation:
2290 Enable semihosting syscall emulation.
2292 On ARM this implements the "Angel" interface.
2294 Note that this allows guest direct access to the host filesystem,
2295 so should only be used with trusted guest OS.
2301 @node ColdFire System emulator
2302 @section ColdFire System emulator
2303 @cindex system emulation (ColdFire)
2304 @cindex system emulation (M68K)
2306 Use the executable @file{qemu-system-m68k} to simulate a ColdFire machine.
2307 The emulator is able to boot a uClinux kernel.
2309 The M5208EVB emulation includes the following devices:
2313 MCF5208 ColdFire V2 Microprocessor (ISA A+ with EMAC).
2315 Three Two on-chip UARTs.
2317 Fast Ethernet Controller (FEC)
2320 The AN5206 emulation includes the following devices:
2324 MCF5206 ColdFire V2 Microprocessor.
2329 @c man begin OPTIONS
2331 The following options are specific to the ColdFire emulation:
2336 Enable semihosting syscall emulation.
2338 On M68K this implements the "ColdFire GDB" interface used by libgloss.
2340 Note that this allows guest direct access to the host filesystem,
2341 so should only be used with trusted guest OS.
2347 @node Cris System emulator
2348 @section Cris System emulator
2349 @cindex system emulation (Cris)
2353 @node Microblaze System emulator
2354 @section Microblaze System emulator
2355 @cindex system emulation (Microblaze)
2359 @node SH4 System emulator
2360 @section SH4 System emulator
2361 @cindex system emulation (SH4)
2365 @node Xtensa System emulator
2366 @section Xtensa System emulator
2367 @cindex system emulation (Xtensa)
2369 Two executables cover simulation of both Xtensa endian options,
2370 @file{qemu-system-xtensa} and @file{qemu-system-xtensaeb}.
2371 Two different machine types are emulated:
2375 Xtensa emulator pseudo board "sim"
2377 Avnet LX60/LX110/LX200 board
2380 The sim pseudo board emulation provides an environment similar
2381 to one provided by the proprietary Tensilica ISS.
2386 A range of Xtensa CPUs, default is the DC232B
2388 Console and filesystem access via semihosting calls
2391 The Avnet LX60/LX110/LX200 emulation supports:
2395 A range of Xtensa CPUs, default is the DC232B
2399 OpenCores 10/100 Mbps Ethernet MAC
2402 @c man begin OPTIONS
2404 The following options are specific to the Xtensa emulation:
2409 Enable semihosting syscall emulation.
2411 Xtensa semihosting provides basic file IO calls, such as open/read/write/seek/select.
2412 Tensilica baremetal libc for ISS and linux platform "sim" use this interface.
2414 Note that this allows guest direct access to the host filesystem,
2415 so should only be used with trusted guest OS.
2421 @node QEMU Guest Agent
2422 @chapter QEMU Guest Agent invocation
2424 @include qemu-ga.texi
2426 @node QEMU User space emulator
2427 @chapter QEMU User space emulator
2430 * Supported Operating Systems ::
2432 * Linux User space emulator::
2433 * BSD User space emulator ::
2436 @node Supported Operating Systems
2437 @section Supported Operating Systems
2439 The following OS are supported in user space emulation:
2443 Linux (referred as qemu-linux-user)
2445 BSD (referred as qemu-bsd-user)
2451 QEMU user space emulation has the following notable features:
2454 @item System call translation:
2455 QEMU includes a generic system call translator. This means that
2456 the parameters of the system calls can be converted to fix
2457 endianness and 32/64-bit mismatches between hosts and targets.
2458 IOCTLs can be converted too.
2460 @item POSIX signal handling:
2461 QEMU can redirect to the running program all signals coming from
2462 the host (such as @code{SIGALRM}), as well as synthesize signals from
2463 virtual CPU exceptions (for example @code{SIGFPE} when the program
2464 executes a division by zero).
2466 QEMU relies on the host kernel to emulate most signal system
2467 calls, for example to emulate the signal mask. On Linux, QEMU
2468 supports both normal and real-time signals.
2471 On Linux, QEMU can emulate the @code{clone} syscall and create a real
2472 host thread (with a separate virtual CPU) for each emulated thread.
2473 Note that not all targets currently emulate atomic operations correctly.
2474 x86 and ARM use a global lock in order to preserve their semantics.
2477 QEMU was conceived so that ultimately it can emulate itself. Although
2478 it is not very useful, it is an important test to show the power of the
2481 @node Linux User space emulator
2482 @section Linux User space emulator
2487 * Command line options::
2492 @subsection Quick Start
2494 In order to launch a Linux process, QEMU needs the process executable
2495 itself and all the target (x86) dynamic libraries used by it.
2499 @item On x86, you can just try to launch any process by using the native
2503 qemu-i386 -L / /bin/ls
2506 @code{-L /} tells that the x86 dynamic linker must be searched with a
2509 @item Since QEMU is also a linux process, you can launch QEMU with
2510 QEMU (NOTE: you can only do that if you compiled QEMU from the sources):
2513 qemu-i386 -L / qemu-i386 -L / /bin/ls
2516 @item On non x86 CPUs, you need first to download at least an x86 glibc
2517 (@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
2518 @code{LD_LIBRARY_PATH} is not set:
2521 unset LD_LIBRARY_PATH
2524 Then you can launch the precompiled @file{ls} x86 executable:
2527 qemu-i386 tests/i386/ls
2529 You can look at @file{scripts/qemu-binfmt-conf.sh} so that
2530 QEMU is automatically launched by the Linux kernel when you try to
2531 launch x86 executables. It requires the @code{binfmt_misc} module in the
2534 @item The x86 version of QEMU is also included. You can try weird things such as:
2536 qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 \
2537 /usr/local/qemu-i386/bin/ls-i386
2543 @subsection Wine launch
2547 @item Ensure that you have a working QEMU with the x86 glibc
2548 distribution (see previous section). In order to verify it, you must be
2552 qemu-i386 /usr/local/qemu-i386/bin/ls-i386
2555 @item Download the binary x86 Wine install
2556 (@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page).
2558 @item Configure Wine on your account. Look at the provided script
2559 @file{/usr/local/qemu-i386/@/bin/wine-conf.sh}. Your previous
2560 @code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.
2562 @item Then you can try the example @file{putty.exe}:
2565 qemu-i386 /usr/local/qemu-i386/wine/bin/wine \
2566 /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
2571 @node Command line options
2572 @subsection Command line options
2575 @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}...]
2582 Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
2584 Set the x86 stack size in bytes (default=524288)
2586 Select CPU model (-cpu help for list and additional feature selection)
2587 @item -E @var{var}=@var{value}
2588 Set environment @var{var} to @var{value}.
2590 Remove @var{var} from the environment.
2592 Offset guest address by the specified number of bytes. This is useful when
2593 the address region required by guest applications is reserved on the host.
2594 This option is currently only supported on some hosts.
2596 Pre-allocate a guest virtual address space of the given size (in bytes).
2597 "G", "M", and "k" suffixes may be used when specifying the size.
2604 Activate logging of the specified items (use '-d help' for a list of log items)
2606 Act as if the host page size was 'pagesize' bytes
2608 Wait gdb connection to port
2610 Run the emulation in single step mode.
2613 Environment variables:
2617 Print system calls and arguments similar to the 'strace' program
2618 (NOTE: the actual 'strace' program will not work because the user
2619 space emulator hasn't implemented ptrace). At the moment this is
2620 incomplete. All system calls that don't have a specific argument
2621 format are printed with information for six arguments. Many
2622 flag-style arguments don't have decoders and will show up as numbers.
2625 @node Other binaries
2626 @subsection Other binaries
2628 @cindex user mode (Alpha)
2629 @command{qemu-alpha} TODO.
2631 @cindex user mode (ARM)
2632 @command{qemu-armeb} TODO.
2634 @cindex user mode (ARM)
2635 @command{qemu-arm} is also capable of running ARM "Angel" semihosted ELF
2636 binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
2637 configurations), and arm-uclinux bFLT format binaries.
2639 @cindex user mode (ColdFire)
2640 @cindex user mode (M68K)
2641 @command{qemu-m68k} is capable of running semihosted binaries using the BDM
2642 (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
2643 coldfire uClinux bFLT format binaries.
2645 The binary format is detected automatically.
2647 @cindex user mode (Cris)
2648 @command{qemu-cris} TODO.
2650 @cindex user mode (i386)
2651 @command{qemu-i386} TODO.
2652 @command{qemu-x86_64} TODO.
2654 @cindex user mode (Microblaze)
2655 @command{qemu-microblaze} TODO.
2657 @cindex user mode (MIPS)
2658 @command{qemu-mips} TODO.
2659 @command{qemu-mipsel} TODO.
2661 @cindex user mode (NiosII)
2662 @command{qemu-nios2} TODO.
2664 @cindex user mode (PowerPC)
2665 @command{qemu-ppc64abi32} TODO.
2666 @command{qemu-ppc64} TODO.
2667 @command{qemu-ppc} TODO.
2669 @cindex user mode (SH4)
2670 @command{qemu-sh4eb} TODO.
2671 @command{qemu-sh4} TODO.
2673 @cindex user mode (SPARC)
2674 @command{qemu-sparc} can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
2676 @command{qemu-sparc32plus} can execute Sparc32 and SPARC32PLUS binaries
2677 (Sparc64 CPU, 32 bit ABI).
2679 @command{qemu-sparc64} can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
2680 SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
2682 @node BSD User space emulator
2683 @section BSD User space emulator
2688 * BSD Command line options::
2692 @subsection BSD Status
2696 target Sparc64 on Sparc64: Some trivial programs work.
2699 @node BSD Quick Start
2700 @subsection Quick Start
2702 In order to launch a BSD process, QEMU needs the process executable
2703 itself and all the target dynamic libraries used by it.
2707 @item On Sparc64, you can just try to launch any process by using the native
2711 qemu-sparc64 /bin/ls
2716 @node BSD Command line options
2717 @subsection Command line options
2720 @command{qemu-sparc64} [@option{-h]} [@option{-d]} [@option{-L} @var{path}] [@option{-s} @var{size}] [@option{-bsd} @var{type}] @var{program} [@var{arguments}...]
2727 Set the library root path (default=/)
2729 Set the stack size in bytes (default=524288)
2730 @item -ignore-environment
2731 Start with an empty environment. Without this option,
2732 the initial environment is a copy of the caller's environment.
2733 @item -E @var{var}=@var{value}
2734 Set environment @var{var} to @var{value}.
2736 Remove @var{var} from the environment.
2738 Set the type of the emulated BSD Operating system. Valid values are
2739 FreeBSD, NetBSD and OpenBSD (default).
2746 Activate logging of the specified items (use '-d help' for a list of log items)
2748 Act as if the host page size was 'pagesize' bytes
2750 Run the emulation in single step mode.
2754 @include qemu-tech.texi
2756 @node Deprecated features
2757 @appendix Deprecated features
2759 In general features are intended to be supported indefinitely once
2760 introduced into QEMU. In the event that a feature needs to be removed,
2761 it will be listed in this appendix. The feature will remain functional
2762 for 2 releases prior to actual removal. Deprecated features may also
2763 generate warnings on the console when QEMU starts up, or if activated
2764 via a monitor command, however, this is not a mandatory requirement.
2766 Prior to the 2.10.0 release there was no official policy on how
2767 long features would be deprecated prior to their removal, nor
2768 any documented list of which features were deprecated. Thus
2769 any features deprecated prior to 2.10.0 will be treated as if
2770 they were first deprecated in the 2.10.0 release.
2772 What follows is a list of all features currently marked as
2775 @section Build options
2779 Previously QEMU has supported building against both GTK 2.x
2780 and 3.x series APIs. Support for the GTK 2.x builds will be
2781 discontinued, so maintainers should switch to using GTK 3.x,
2782 which is the default.
2786 Previously QEMU has supported building against both SDL 1.2
2787 and 2.0 series APIs. Support for the SDL 1.2 builds will be
2788 discontinued, so maintainers should switch to using SDL 2.0,
2789 which is the default.
2791 @section System emulator command line arguments
2793 @subsection -no-kvm-pit-reinjection (since 1.3.0)
2795 The ``-no-kvm-pit-reinjection'' argument is now a
2796 synonym for setting ``-global kvm-pit.lost_tick_policy=discard''.
2798 @subsection -no-kvm-irqchip (since 1.3.0)
2800 The ``-no-kvm-irqchip'' argument is now a synonym for
2801 setting ``-machine kernel_irqchip=off''.
2803 @subsection -no-kvm (since 1.3.0)
2805 The ``-no-kvm'' argument is now a synonym for setting
2806 ``-machine accel=tcg''.
2808 @subsection -vnc tls (since 2.5.0)
2810 The ``-vnc tls'' argument is now a synonym for setting
2811 ``-object tls-creds-anon,id=tls0'' combined with
2812 ``-vnc tls-creds=tls0'
2814 @subsection -vnc x509 (since 2.5.0)
2816 The ``-vnc x509=/path/to/certs'' argument is now a
2818 ``-object tls-creds-x509,dir=/path/to/certs,id=tls0,verify-peer=no''
2819 combined with ``-vnc tls-creds=tls0'
2821 @subsection -vnc x509verify (since 2.5.0)
2823 The ``-vnc x509verify=/path/to/certs'' argument is now a
2825 ``-object tls-creds-x509,dir=/path/to/certs,id=tls0,verify-peer=yes''
2826 combined with ``-vnc tls-creds=tls0'
2828 @subsection -tftp (since 2.6.0)
2830 The ``-tftp /some/dir'' argument is replaced by either
2831 ``-netdev user,id=x,tftp=/some/dir '' (for pluggable NICs, accompanied
2832 with ``-device ...,netdev=x''), or ``-nic user,tftp=/some/dir''
2833 (for embedded NICs). The new syntax allows different settings to be
2836 @subsection -bootp (since 2.6.0)
2838 The ``-bootp /some/file'' argument is replaced by either
2839 ``-netdev user,id=x,bootp=/some/file '' (for pluggable NICs, accompanied
2840 with ``-device ...,netdev=x''), or ``-nic user,bootp=/some/file''
2841 (for embedded NICs). The new syntax allows different settings to be
2844 @subsection -redir (since 2.6.0)
2846 The ``-redir [tcp|udp]:hostport:[guestaddr]:guestport'' argument is
2848 ``-netdev user,id=x,hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport''
2849 (for pluggable NICs, accompanied with ``-device ...,netdev=x'') or
2850 ``-nic user,hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport''
2851 (for embedded NICs). The new syntax allows different settings to be
2854 @subsection -smb (since 2.6.0)
2856 The ``-smb /some/dir'' argument is replaced by either
2857 ``-netdev user,id=x,smb=/some/dir '' (for pluggable NICs, accompanied
2858 with ``-device ...,netdev=x''), or ``-nic user,smb=/some/dir''
2859 (for embedded NICs). The new syntax allows different settings to be
2862 @subsection -drive cyls=...,heads=...,secs=...,trans=... (since 2.10.0)
2864 The drive geometry arguments are replaced by the the geometry arguments
2865 that can be specified with the ``-device'' parameter.
2867 @subsection -drive serial=... (since 2.10.0)
2869 The drive serial argument is replaced by the the serial argument
2870 that can be specified with the ``-device'' parameter.
2872 @subsection -drive addr=... (since 2.10.0)
2874 The drive addr argument is replaced by the the addr argument
2875 that can be specified with the ``-device'' parameter.
2877 @subsection -usbdevice (since 2.10.0)
2879 The ``-usbdevice DEV'' argument is now a synonym for setting
2880 the ``-device usb-DEV'' argument instead. The deprecated syntax
2881 would automatically enable USB support on the machine type.
2882 If using the new syntax, USB support must be explicitly
2883 enabled via the ``-machine usb=on'' argument.
2885 @subsection -nodefconfig (since 2.11.0)
2887 The ``-nodefconfig`` argument is a synonym for ``-no-user-config``.
2889 @subsection -balloon (since 2.12.0)
2891 The @option{--balloon virtio} argument has been superseded by
2892 @option{--device virtio-balloon}.
2894 @subsection -machine s390-squash-mcss=on|off (since 2.12.0)
2896 The ``s390-squash-mcss=on`` property has been obsoleted by allowing the
2897 cssid to be chosen freely. Instead of squashing subchannels into the
2898 default channel subsystem image for guests that do not support multiple
2899 channel subsystems, all devices can be put into the default channel
2902 @subsection -fsdev handle (since 2.12.0)
2904 The ``handle'' fsdev backend does not support symlinks and causes the 9p
2905 filesystem in the guest to fail a fair amount of tests from the PJD POSIX
2906 filesystem test suite. Also it requires the CAP_DAC_READ_SEARCH capability,
2907 which is not the recommended way to run QEMU. This backend should not be
2908 used and it will be removed with no replacement.
2910 @subsection -no-frame (since 2.12.0)
2912 The @code{--no-frame} argument works with SDL 1.2 only. The other user
2913 interfaces never implemented this in the first place. So this will be
2914 removed together with SDL 1.2 support.
2916 @subsection -rtc-td-hack (since 2.12.0)
2918 The @code{-rtc-td-hack} option has been replaced by
2919 @code{-rtc driftfix=slew}.
2921 @subsection -localtime (since 2.12.0)
2923 The @code{-localtime} option has been replaced by @code{-rtc base=localtime}.
2925 @subsection -startdate (since 2.12.0)
2927 The @code{-startdate} option has been replaced by @code{-rtc base=@var{date}}.
2929 @section qemu-img command line arguments
2931 @subsection convert -s (since 2.0.0)
2933 The ``convert -s snapshot_id_or_name'' argument is obsoleted
2934 by the ``convert -l snapshot_param'' argument instead.
2936 @section QEMU Machine Protocol (QMP) commands
2938 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
2940 "autoload" parameter is now ignored. All bitmaps are automatically loaded
2943 @subsection query-cpus (since 2.12.0)
2945 The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
2947 @subsection query-cpus-fast "arch" output member (since 2.13.0)
2949 The ``arch'' output member of the ``query-cpus-fast'' command is
2950 replaced by the ``target'' output member.
2952 @section System emulator devices
2954 @subsection ivshmem (since 2.6.0)
2956 The ``ivshmem'' device type is replaced by either the ``ivshmem-plain''
2957 or ``ivshmem-doorbell`` device types.
2959 @subsection Page size support < 4k for embedded PowerPC CPUs (since 2.12.0)
2961 qemu-system-ppcemb will be removed. qemu-system-ppc (or qemu-system-ppc64)
2962 should be used instead. That means that embedded 4xx PowerPC CPUs will not
2963 support page sizes < 4096 any longer.
2965 @section System emulator machines
2967 @subsection Xilinx EP108 (since 2.11.0)
2969 The ``xlnx-ep108'' machine has been replaced by the ``xlnx-zcu102'' machine.
2970 The ``xlnx-zcu102'' machine has the same features and capabilites in QEMU.
2972 @section Block device options
2974 @subsection "backing": "" (since 2.12.0)
2976 In order to prevent QEMU from automatically opening an image's backing
2977 chain, use ``"backing": null'' instead.
2982 QEMU is a trademark of Fabrice Bellard.
2984 QEMU is released under the
2985 @url{https://www.gnu.org/licenses/gpl-2.0.txt,GNU General Public License},
2986 version 2. Parts of QEMU have specific licenses, see file
2987 @url{https://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE,LICENSE}.
3001 @section Concept Index
3002 This is the main index. Should we combine all keywords in one index? TODO
3005 @node Function Index
3006 @section Function Index
3007 This index could be used for command line options and monitor functions.
3010 @node Keystroke Index
3011 @section Keystroke Index
3013 This is a list of all keystrokes which have a special function
3014 in system emulation.
3019 @section Program Index
3022 @node Data Type Index
3023 @section Data Type Index
3025 This index could be used for qdev device names and options.
3029 @node Variable Index
3030 @section Variable Index