     [file version.texi not included]

Introduction
************

Features
========

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

QEMU has two operating modes:

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

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

QEMU has the following features:

  * QEMU can run without a host kernel driver and yet gives acceptable performance.  It uses dynamic translation to native code for reasonable speed, with support for self-modifying code and precise exceptions.

  * It is portable to several operating systems (GNU/Linux, *BSD, Mac OS X, Windows) and architectures.

  * It performs accurate software emulation of the FPU.

QEMU user mode emulation has the following features:

  * Generic Linux system call converter, including most ioctls.

  * clone() emulation using native CPU clone() to use Linux scheduler for threads.

  * Accurate signal handling by remapping host signals to target signals.

QEMU full system emulation has the following features:

  * QEMU uses a full software MMU for maximum portability.

  * QEMU can optionally use an in-kernel accelerator, like kvm. The accelerators execute most of the guest code natively, while continuing to emulate the rest of the machine.

  * Various hardware devices can be emulated and in some cases, host devices (e.g. serial and parallel ports, USB, drives) can be used transparently by the guest Operating System. Host device passthrough can be used for talking to external physical peripherals (e.g. a webcam, modem or tape drive).

  * Symmetric multiprocessing (SMP) support.  Currently, an in-kernel accelerator is required to use more than one host CPU for emulation.

QEMU PC System emulator
***********************

Introduction
============

The QEMU PC System emulator simulates the following peripherals:

  - i440FX host PCI bridge and PIIX3 PCI to ISA bridge

  - Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA extensions (hardware level, including all non standard modes).

  - PS/2 mouse and keyboard

  - 2 PCI IDE interfaces with hard disk and CD-ROM support

  - Floppy disk

  - PCI and ISA network adapters

  - Serial ports

  - IPMI BMC, either and internal or external one

  - Creative SoundBlaster 16 sound card

  - ENSONIQ AudioPCI ES1370 sound card

  - Intel 82801AA AC97 Audio compatible sound card

  - Intel HD Audio Controller and HDA codec

  - Adlib (OPL2) - Yamaha YM3812 compatible chip

  - Gravis Ultrasound GF1 sound card

  - CS4231A compatible sound card

  - PCI UHCI, OHCI, EHCI or XHCI USB controller and a virtual USB-1.1 hub.

SMP is supported with up to 255 CPUs.

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

QEMU uses YM3812 emulation by Tatsuyuki Satoh.

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

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

     qemu-system-i386 dos.img -soundhw gus -parallel none

Alternatively:

     qemu-system-i386 dos.img -device gus,irq=5

Or some other unclaimed IRQ.

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

Quick Start
===========

Download and uncompress the linux image (linux.img) and type:

     qemu-system-i386 linux.img

Linux should boot and give you a prompt.

Invocation
==========

     qemu-system-i386 [OPTIONS] [DISK_IMAGE]

DISK_IMAGE is a raw hard disk image for IDE hard disk 0. Some targets do not need a disk image.

     [file qemu-options.texi not included]

Device URL Syntax
-----------------

In addition to using normal file images for the emulated storage devices, QEMU can also use networked resources such as iSCSI devices. These are specified using a special URL syntax.

iSCSI
     iSCSI support allows QEMU to access iSCSI resources directly and use as images for the guest storage. Both disk and cdrom images are supported.

     Syntax for specifying iSCSI LUNs is ``iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>''

     By default qemu will use the iSCSI initiator-name 'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command line or a configuration file.

     Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect stalled requests and force a reestablishment of the session. The timeout is specified in seconds. The default is 0 which means no timeout. Libiscsi 1.15.0 or greater is required for this feature.

     Example (without authentication):

          qemu-system-i386 -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \
                           -cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \
                           -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1

     Example (CHAP username/password via URL):

          qemu-system-i386 -drive file=iscsi://user%password@192.0.2.1/iqn.2001-04.com.example/1

     Example (CHAP username/password via environment variables):

          LIBISCSI_CHAP_USERNAME="user" \
          LIBISCSI_CHAP_PASSWORD="password" \
          qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1

NBD
     QEMU supports NBD (Network Block Devices) both using TCP protocol as well as Unix Domain Sockets.

     Syntax for specifying a NBD device using TCP ``nbd:<server-ip>:<port>[:exportname=<export>]''

     Syntax for specifying a NBD device using Unix Domain Sockets ``nbd:unix:<domain-socket>[:exportname=<export>]''

     Example for TCP

          qemu-system-i386 --drive file=nbd:192.0.2.1:30000

     Example for Unix Domain Sockets

          qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket

SSH
     QEMU supports SSH (Secure Shell) access to remote disks.

     Examples:

          qemu-system-i386 -drive file=ssh://user@host/path/to/disk.img
          qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img

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

Sheepdog
     Sheepdog is a distributed storage system for QEMU. QEMU supports using either local sheepdog devices or remote networked devices.

     Syntax for specifying a sheepdog device

          sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]

     Example

          qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine

     See also https://sheepdog.github.io/sheepdog/.

GlusterFS
     GlusterFS is a user space distributed file system. QEMU supports the use of GlusterFS volumes for hosting VM disk images using TCP, Unix Domain Sockets and RDMA transport protocols.

     Syntax for specifying a VM disk image on GlusterFS volume is

          URI:
          gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...]

          JSON:
          'json:{"driver":"qcow2","file":{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...",
                                           "server":[{"type":"tcp","host":"...","port":"..."},
                                                     {"type":"unix","socket":"..."}]}}'

     Example

          URI:
          qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img,
                                         file.debug=9,file.logfile=/var/log/qemu-gluster.log

          JSON:
          qemu-system-x86_64 'json:{"driver":"qcow2",
                                    "file":{"driver":"gluster",
                                             "volume":"testvol","path":"a.img",
                                             "debug":9,"logfile":"/var/log/qemu-gluster.log",
                                             "server":[{"type":"tcp","host":"1.2.3.4","port":24007},
                                                       {"type":"unix","socket":"/var/run/glusterd.socket"}]}}'
          qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
                                                file.debug=9,file.logfile=/var/log/qemu-gluster.log,
                                                file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
                                                file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket

     See also http://www.gluster.org.

HTTP/HTTPS/FTP/FTPS
     QEMU supports read-only access to files accessed over http(s) and ftp(s).

     Syntax using a single filename:

          <protocol>://[<username>[:<password>]@]<host>/<path>

     where:

     protocol
          'http', 'https', 'ftp', or 'ftps'.

     username
          Optional username for authentication to the remote server.

     password
          Optional password for authentication to the remote server.

     host
          Address of the remote server.

     path
          Path on the remote server, including any query string.

     The following options are also supported:

     url
          The full URL when passing options to the driver explicitly.

     readahead
          The amount of data to read ahead with each range request to the remote server. This value may optionally have the suffix 'T', 'G', 'M', 'K', 'k' or 'b'. If it does not have a suffix, it will be assumed to be in bytes. The value must be a multiple of 512 bytes. It defaults to 256k.

     sslverify
          Whether to verify the remote server's certificate when connecting over SSL. It can have the value 'on' or 'off'. It defaults to 'on'.

     cookie
          Send this cookie (it can also be a list of cookies separated by ';') with each outgoing request.  Only supported when using protocols such as HTTP which support cookies, otherwise ignored.

     timeout
          Set the timeout in seconds of the CURL connection. This timeout is the time that CURL waits for a response from the remote server to get the size of the image to be downloaded. If not set, the default timeout of 5 seconds is used.

     Note that when passing options to qemu explicitly, driver is the value of <protocol>.

     Example: boot from a remote Fedora 20 live ISO image

          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

          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

     Example: boot from a remote Fedora 20 cloud image using a local overlay for writes, copy-on-read, and a readahead of 64k

          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

          qemu-system-x86_64 -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on

     Example: boot from an image stored on a VMware vSphere server with a self-signed certificate using a local overlay for writes, a readahead of 64k and a timeout of 10 seconds.

          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

          qemu-system-x86_64 -drive file=/tmp/test.qcow2

Keys in the graphical frontends
===============================

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

Ctrl-Alt-f
     Toggle full screen

Ctrl-Alt-+
     Enlarge the screen

Ctrl-Alt--
     Shrink the screen

Ctrl-Alt-u
     Restore the screen's un-scaled dimensions

Ctrl-Alt-n
     Switch to virtual console 'n'. Standard console mappings are:

     1
          Target system display

     2
          Monitor

     3
          Serial port

Ctrl-Alt
     Toggle mouse and keyboard grab.

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

Keys in the character backend multiplexer
=========================================

During emulation, if you are using a character backend multiplexer (which is the default if you are using -nographic) then several commands are available via an escape sequence. These key sequences all start with an escape character, which is Ctrl-a by default, but can be changed with -echr. The list below assumes you're using the default.

Ctrl-a h
     Print this help

Ctrl-a x
     Exit emulator

Ctrl-a s
     Save disk data back to file (if -snapshot)

Ctrl-a t
     Toggle console timestamps

Ctrl-a b
     Send break (magic sysrq in Linux)

Ctrl-a c
     Rotate between the frontends connected to the multiplexer (usually this switches between the monitor and the console)

Ctrl-a Ctrl-a
     Send the escape character to the frontend

QEMU Monitor
============

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

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

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

  - Inspect the VM state without an external debugger.

Commands
--------

The following commands are available:

     [file qemu-monitor.texi not included]

     [file qemu-monitor-info.texi not included]

Integer expressions
-------------------

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

CPU models
==========

     [file qemu-cpu-models.texi not included]

Disk Images
===========

QEMU supports many disk image formats, including growable disk images (their size increase as non empty sectors are written), compressed and encrypted disk images.

Quick start for disk image creation
-----------------------------------

You can create a disk image with the command:

     qemu-img create myimage.img mysize

where MYIMAGE.IMG is the disk image filename and MYSIZE is its size in kilobytes. You can add an M suffix to give the size in megabytes and a G suffix for gigabytes.

See qemu_img_invocation for more information.

Snapshot mode
-------------

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

VM snapshots
------------

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

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

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

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

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

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

VM snapshots currently have the following known limitations:

  * They cannot cope with removable devices if they are removed or inserted after a snapshot is done.

  * A few device drivers still have incomplete snapshot support so their state is not saved or restored properly (in particular USB).

qemu-img Invocation
-------------------

     [file qemu-img.texi not included]

qemu-nbd Invocation
-------------------

     [file qemu-nbd.texi not included]

     [file qemu-block-drivers.texi not included]

Network emulation
=================

QEMU can simulate several network cards (e.g. PCI or ISA cards on the PC target) and can connect them to a network backend on the host or an emulated hub. The various host network backends can either be used to connect the NIC of the guest to a real network (e.g. by using a TAP devices or the non-privileged user mode network stack), or to other guest instances running in another QEMU process (e.g. by using the socket host network backend).

Using TAP network interfaces
----------------------------

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

Linux host
..........

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

See sec_invocation to have examples of command lines using the TAP network interfaces.

Windows host
............

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

Using the user mode network stack
---------------------------------

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

          guest (10.0.2.15)  <------>  Firewall/DHCP server <-----> Internet
                                |          (10.0.2.2)
                                |
                                ---->  DNS server (10.0.2.3)
                                |
                                ---->  SMB server (10.0.2.4)

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

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

Note that ICMP traffic in general does not work with user mode networking. ping, aka. ICMP echo, to the local router (10.0.2.2) shall work, however. If you're using QEMU on Linux >= 3.0, it can use unprivileged ICMP ping sockets to allow ping to the Internet. The host admin has to set the ping_group_range in order to grant access to those sockets. To allow ping for GID 100 (usually users group):

     echo 100 100 > /proc/sys/net/ipv4/ping_group_range

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

When using the '-netdev user,hostfwd=...' option, TCP or UDP connections can be redirected from the host to the guest. It allows for example to redirect X11, telnet or SSH connections.

Hubs
----

QEMU can simulate several hubs. A hub can be thought of as a virtual connection between several network devices. These devices can be for example QEMU virtual ethernet cards or virtual Host ethernet devices (TAP devices). You can connect guest NICs or host network backends to such a hub using the -netdev hubport or -nic hubport options. The legacy -net option also connects the given device to the emulated hub with ID 0 (i.e. the default hub) unless you specify a netdev with -net nic,netdev=xxx here.

Connecting emulated networks between QEMU instances
---------------------------------------------------

Using the -netdev socket (or -nic socket or -net socket) option, it is possible to create emulated networks that span several QEMU instances. See the description of the -netdev socket option in the Invocation chapter to have a basic example.

Other Devices
=============

Inter-VM Shared Memory device
-----------------------------

On Linux hosts, a shared memory device is available.  The basic syntax is:

     qemu-system-x86_64 -device ivshmem-plain,memdev=HOSTMEM

where HOSTMEM names a host memory backend.  For a POSIX shared memory backend, use something like

     -object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=HOSTMEM

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

     # First start the ivshmem server once and for all
     ivshmem-server -p PIDFILE -S PATH -m SHM-NAME -l SHM-SIZE -n VECTORS

     # Then start your qemu instances with matching arguments
     qemu-system-x86_64 -device ivshmem-doorbell,vectors=VECTORS,chardev=ID
                      -chardev socket,path=PATH,id=ID

When using the server, the guest will be assigned a VM ID (>=0) that allows guests using the same server to communicate via interrupts.  Guests can read their VM ID from a device register (see ivshmem-spec.txt).

Migration with ivshmem
......................

With device property master=on, the guest will copy the shared memory on migration to the destination host.  With master=off, the guest will not be able to migrate with the device attached.  In the latter case, the device should be detached and then reattached after migration using the PCI hotplug support.

At most one of the devices sharing the same memory can be master.  The master must complete migration before you plug back the other devices.

ivshmem and hugepages
.....................

Instead of specifying the <shm size> using POSIX shm, you may specify a memory backend that has hugepage support:

     qemu-system-x86_64 -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,id=mb1
                      -device ivshmem-plain,memdev=mb1

ivshmem-server also supports hugepages mount points with the -m memory path argument.

Direct Linux Boot
=================

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

The syntax is:

     qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"

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

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

If you do not need graphical output, you can disable it and redirect the virtual serial port and the QEMU monitor to the console with the -nographic option. The typical command line is:

     qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
                      -append "root=/dev/hda console=ttyS0" -nographic

Use Ctrl-a c to switch between the serial console and the monitor (see pcsys_keys).

USB emulation
=============

QEMU can emulate a PCI UHCI, OHCI, EHCI or XHCI USB controller. You can plug virtual USB devices or real host USB devices (only works with certain host operating systems). QEMU will automatically create and connect virtual USB hubs as necessary to connect multiple USB devices.

Connecting USB devices
----------------------

USB devices can be connected with the -device usb-... command line option or the device_add monitor command. Available devices are:

usb-mouse
     Virtual Mouse.  This will override the PS/2 mouse emulation when activated.

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

usb-storage,drive=DRIVE_ID
     Mass storage device backed by DRIVE_ID (see disk_images)

usb-uas
     USB attached SCSI device, see usb-storage.txt (https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt) for details

usb-bot
     Bulk-only transport storage device, see usb-storage.txt (https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb-storage.txt) for details here, too

usb-mtp,rootdir=DIR
     Media transfer protocol device, using DIR as root of the file tree that is presented to the guest.

usb-host,hostbus=BUS,hostaddr=ADDR
     Pass through the host device identified by BUS and ADDR

usb-host,vendorid=VENDOR,productid=PRODUCT
     Pass through the host device identified by VENDOR and PRODUCT ID

usb-wacom-tablet
     Virtual Wacom PenPartner tablet.  This device is similar to the tablet above but it can be used with the tslib library because in addition to touch coordinates it reports touch pressure.

usb-kbd
     Standard USB keyboard.  Will override the PS/2 keyboard (if present).

usb-serial,chardev=ID
     Serial converter. This emulates an FTDI FT232BM chip connected to host character device ID.

usb-braille,chardev=ID
     Braille device.  This will use BrlAPI to display the braille output on a real or fake device referenced by ID.

usb-net[,netdev=ID]
     Network adapter that supports CDC ethernet and RNDIS protocols.  ID specifies a netdev defined with -netdev ...,id=ID. For instance, user-mode networking can be used with

          qemu-system-i386 [...] -netdev user,id=net0 -device usb-net,netdev=net0

usb-ccid
     Smartcard reader device

usb-audio
     USB audio device

usb-bt-dongle
     Bluetooth dongle for the transport layer of HCI. It is connected to HCI scatternet 0 by default (corresponds to -bt hci,vlan=0). Note that the syntax for the -device usb-bt-dongle option is not as useful yet as it was with the legacy -usbdevice option. So to configure an USB bluetooth device, you might need to use "-usbdevice bt[:HCI-TYPE]" instead. This configures a bluetooth dongle whose type is specified in the same format as with the -bt hci option, see allowed HCI types.  If no type is given, the HCI logic corresponds to -bt hci,vlan=0. This USB device implements the USB Transport Layer of HCI.  Example usage:

          qemu-system-i386 [...OPTIONS...] -usbdevice bt:hci,vlan=3 -bt device:keyboard,vlan=3

Using host USB devices on a Linux host
--------------------------------------

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

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

 2. Verify that /proc/bus/usb is working (most Linux distributions should enable it by default). You should see something like that:

          ls /proc/bus/usb
          001  devices  drivers

 3. 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:

          chown -R myuid /proc/bus/usb

 4. Launch QEMU and do in the monitor:

          info usbhost
            Device 1.2, speed 480 Mb/s
              Class 00: USB device 1234:5678, USB DISK

     You should see the list of the devices you can use (Never try to use hubs, it won't work).

 5. Add the device in QEMU by using:

          device_add usb-host,vendorid=0x1234,productid=0x5678

     Normally the guest OS should report that a new USB device is plugged. You can use the option -device usb-host,... to do the same.

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

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

VNC security
============

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

Without passwords
-----------------

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

     qemu-system-i386 [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc

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

With passwords
--------------

The VNC protocol has limited support for password based authentication. Since the protocol limits passwords to 8 characters it should not be considered to provide high security. The password can be fairly easily brute-forced by a client making repeat connections. For this reason, a VNC server using password authentication should be restricted to only listen on the loopback interface or UNIX domain sockets. Password authentication is not supported when operating in FIPS 140-2 compliance mode as it requires the use of the DES cipher. Password authentication is requested with the password option, and then once QEMU is running the password is set with the monitor. Until the monitor is used to set the password all clients will be rejected.

     qemu-system-i386 [...OPTIONS...] -vnc :1,password -monitor stdio
     (qemu) change vnc password
     Password: ********
     (qemu)

With x509 certificates
----------------------

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

     qemu-system-i386 [...OPTIONS...] \
       -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=no \
       -vnc :1,tls-creds=tls0 -monitor stdio

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

With x509 certificates and client verification
----------------------------------------------

Certificates can also provide a means to authenticate the client connecting. The server will request that the client provide a certificate, which it will then validate against the CA certificate. This is a good choice if deploying in an environment with a private internal certificate authority. It uses the same syntax as previously, but with verify-peer set to yes instead.

     qemu-system-i386 [...OPTIONS...] \
       -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
       -vnc :1,tls-creds=tls0 -monitor stdio

With x509 certificates, client verification and passwords
---------------------------------------------------------

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

     qemu-system-i386 [...OPTIONS...] \
       -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
       -vnc :1,tls-creds=tls0,password -monitor stdio
     (qemu) change vnc password
     Password: ********
     (qemu)

With SASL authentication
------------------------

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

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

     qemu-system-i386 [...OPTIONS...] -vnc :1,sasl -monitor stdio

With x509 certificates and SASL authentication
----------------------------------------------

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

     qemu-system-i386 [...OPTIONS...] \
       -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server,verify-peer=yes \
       -vnc :1,tls-creds=tls0,sasl -monitor stdio

Configuring SASL mechanisms
---------------------------

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

If the TLS option is enabled for VNC, then it will provide session encryption, otherwise the SASL mechanism will have to provide encryption. In the latter case the list of possible plugins that can be used is drastically reduced. In fact only the GSSAPI SASL mechanism provides an acceptable level of security by modern standards. Previous versions of QEMU referred to the DIGEST-MD5 mechanism, however, it has multiple serious flaws described in detail in RFC 6331 and thus should never be used any more. The SCRAM-SHA-1 mechanism provides a simple username/password auth facility similar to DIGEST-MD5, but does not support session encryption, so can only be used in combination with TLS.

When not using TLS the recommended configuration is

     mech_list: gssapi
     keytab: /etc/qemu/krb5.tab

This says to use the 'GSSAPI' mechanism with the Kerberos v5 protocol, with the server principal stored in /etc/qemu/krb5.tab. For this to work the administrator of your KDC must generate a Kerberos principal for the server, with a name of 'qemu/somehost.example.com@EXAMPLE.COM' replacing 'somehost.example.com' with the fully qualified host name of the machine running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm.

When using TLS, if username+password authentication is desired, then a reasonable configuration is

     mech_list: scram-sha-1
     sasldb_path: /etc/qemu/passwd.db

The saslpasswd2 program can be used to populate the passwd.db file with accounts.

Other SASL configurations will be left as an exercise for the reader. Note that all mechanisms, except GSSAPI, should be combined with use of TLS to ensure a secure data channel.

TLS setup for network services
==============================

Almost all network services in QEMU have the ability to use TLS for session data encryption, along with x509 certificates for simple client authentication. What follows is a description of how to generate certificates suitable for usage with QEMU, and applies to the VNC server, character devices with the TCP backend, NBD server and client, and migration server and client.

At a high level, QEMU requires certificates and private keys to be provided in PEM format. Aside from the core fields, the certificates should include various extension data sets, including v3 basic constraints data, key purpose, key usage and subject alt name.

The GnuTLS package includes a command called certtool which can be used to easily generate certificates and keys in the required format with expected data present. Alternatively a certificate management service may be used.

At a minimum it is necessary to setup a certificate authority, and issue certificates to each server. If using x509 certificates for authentication, then each client will also need to be issued a certificate.

Assuming that the QEMU network services will only ever be exposed to clients on a private intranet, there is no need to use a commercial certificate authority to create certificates. A self-signed CA is sufficient, and in fact likely to be more secure since it removes the ability of malicious 3rd parties to trick the CA into mis-issuing certs for impersonating your services. The only likely exception where a commercial CA might be desirable is if enabling the VNC websockets server and exposing it directly to remote browser clients. In such a case it might be useful to use a commercial CA to avoid needing to install custom CA certs in the web browsers.

The recommendation is for the server to keep its certificates in either /etc/pki/qemu or for unprivileged users in $HOME/.pki/qemu.

Setup the Certificate Authority
-------------------------------

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

     # certtool --generate-privkey > ca-key.pem

To generate a self-signed certificate requires one core piece of information, the name of the organization. A template file ca.info should be populated with the desired data to avoid having to deal with interactive prompts from certtool:

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

The ca keyword in the template sets the v3 basic constraints extension to indicate this certificate is for a CA, while cert_signing_key sets the key usage extension to indicate this will be used for signing other keys. The generated ca-cert.pem file should be copied to all servers and clients wishing to utilize TLS support in the VNC server. The ca-key.pem must not be disclosed/copied anywhere except the host responsible for issuing certificates.

Issuing server certificates
---------------------------

Each server (or host) needs to be issued with a key and certificate. When connecting the certificate is sent to the client which validates it against the CA certificate. The core pieces of information for a server certificate are the hostnames and/or IP addresses that will be used by clients when connecting. The hostname / IP address that the client specifies when connecting will be validated against the hostname(s) and IP address(es) recorded in the server certificate, and if no match is found the client will close the connection.

Thus it is recommended that the server certificate include both the fully qualified and unqualified hostnames. If the server will have permanently assigned IP address(es), and clients are likely to use them when connecting, they may also be included in the certificate. Both IPv4 and IPv6 addresses are supported. Historically certificates only included 1 hostname in the CN field, however, usage of this field for validation is now deprecated. Instead modern TLS clients will validate against the Subject Alt Name extension data, which allows for multiple entries. In the future usage of the CN field may be discontinued entirely, so providing SAN extension data is strongly recommended.

On the host holding the CA, create template files containing the information for each server, and use it to issue server certificates.

     # cat > server-hostNNN.info <<EOF
     organization = Name  of your organization
     cn = hostNNN.foo.example.com
     dns_name = hostNNN
     dns_name = hostNNN.foo.example.com
     ip_address = 10.0.1.87
     ip_address = 192.8.0.92
     ip_address = 2620:0:cafe::87
     ip_address = 2001:24::92
     tls_www_server
     encryption_key
     signing_key
     EOF
     # certtool --generate-privkey > server-hostNNN-key.pem
     # certtool --generate-certificate \
                --load-ca-certificate ca-cert.pem \
                --load-ca-privkey ca-key.pem \
                --load-privkey server-hostNNN-key.pem \
                --template server-hostNNN.info \
                --outfile server-hostNNN-cert.pem

The dns_name and ip_address fields in the template are setting the subject alt name extension data. The tls_www_server keyword is the key purpose extension to indicate this certificate is intended for usage in a web server. Although QEMU network services are not in fact HTTP servers (except for VNC websockets), setting this key purpose is still recommended. The encryption_key and signing_key keyword is the key usage extension to indicate this certificate is intended for usage in the data session.

The server-hostNNN-key.pem and server-hostNNN-cert.pem files should now be securely copied to the server for which they were generated, and renamed to server-key.pem and server-cert.pem when added to the /etc/pki/qemu directory on the target host. The server-key.pem file is security sensitive and should be kept protected with file mode 0600 to prevent disclosure.

Issuing client certificates
---------------------------

The QEMU x509 TLS credential setup defaults to enabling client verification using certificates, providing a simple authentication mechanism. If this default is used, each client also needs to be issued a certificate. The client certificate contains enough metadata to uniquely identify the client with the scope of the certificate authority. The client certificate would typically include fields for organization, state, city, building, etc.

Once again on the host holding the CA, create template files containing the information for each client, and use it to issue client certificates.

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

The subject alt name extension data is not required for clients, so the the dns_name and ip_address fields are not included. The tls_www_client keyword is the key purpose extension to indicate this certificate is intended for usage in a web client. Although QEMU network clients are not in fact HTTP clients, setting this key purpose is still recommended. The encryption_key and signing_key keyword is the key usage extension to indicate this certificate is intended for usage in the data session.

The client-hostNNN-key.pem and client-hostNNN-cert.pem files should now be securely copied to the client for which they were generated, and renamed to client-key.pem and client-cert.pem when added to the /etc/pki/qemu directory on the target host. The client-key.pem file is security sensitive and should be kept protected with file mode 0600 to prevent disclosure.

If a single host is going to be using TLS in both a client and server role, it is possible to create a single certificate to cover both roles. This would be quite common for the migration and NBD services, where a QEMU process will be started by accepting a TLS protected incoming migration, and later itself be migrated out to another host. To generate a single certificate, simply include the template data from both the client and server instructions in one.

     # cat > both-hostNNN.info <<EOF
     country = GB
     state = London
     locality = City Of London
     organization = Name of your organization
     cn = hostNNN.foo.example.com
     dns_name = hostNNN
     dns_name = hostNNN.foo.example.com
     ip_address = 10.0.1.87
     ip_address = 192.8.0.92
     ip_address = 2620:0:cafe::87
     ip_address = 2001:24::92
     tls_www_server
     tls_www_client
     encryption_key
     signing_key
     EOF
     # certtool --generate-privkey > both-hostNNN-key.pem
     # certtool --generate-certificate \
                --load-ca-certificate ca-cert.pem \
                --load-ca-privkey ca-key.pem \
                --load-privkey both-hostNNN-key.pem \
                --template both-hostNNN.info \
                --outfile both-hostNNN-cert.pem

When copying the PEM files to the target host, save them twice, once as server-cert.pem and server-key.pem, and again as client-cert.pem and client-key.pem.

TLS x509 credential configuration
---------------------------------

QEMU has a standard mechanism for loading x509 credentials that will be used for network services and clients. It requires specifying the tls-creds-x509 class name to the --object command line argument for the system emulators.  Each set of credentials loaded should be given a unique string identifier via the id parameter. A single set of TLS credentials can be used for multiple network backends, so VNC, migration, NBD, character devices can all share the same credentials. Note, however, that credentials for use in a client endpoint must be loaded separately from those used in a server endpoint.

When specifying the object, the dir parameters specifies which directory contains the credential files. This directory is expected to contain files with the names mentioned previously, ca-cert.pem, server-key.pem, server-cert.pem, client-key.pem and client-cert.pem as appropriate. It is also possible to include a set of pre-generated Diffie-Hellman (DH) parameters in a file dh-params.pem, which can be created using the certtool --generate-dh-params command. If omitted, QEMU will dynamically generate DH parameters when loading the credentials.

The endpoint parameter indicates whether the credentials will be used for a network client or server, and determines which PEM files are loaded.

The verify parameter determines whether x509 certificate validation should be performed. This defaults to enabled, meaning clients will always validate the server hostname against the certificate subject alt name fields and/or CN field. It also means that servers will request that clients provide a certificate and validate them. Verification should never be turned off for client endpoints, however, it may be turned off for server endpoints if an alternative mechanism is used to authenticate clients. For example, the VNC server can use SASL to authenticate clients instead.

To load server credentials with client certificate validation enabled

     $QEMU -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=server

while to load client credentials use

     $QEMU -object tls-creds-x509,id=tls0,dir=/etc/pki/qemu,endpoint=client

Network services which support TLS will all have a tls-creds parameter which expects the ID of the TLS credentials object. For example with VNC:

     $QEMU -vnc 0.0.0.0:0,tls-creds=tls0

TLS Pre-Shared Keys (PSK)
-------------------------

Instead of using certificates, you may also use TLS Pre-Shared Keys (TLS-PSK).  This can be simpler to set up than certificates but is less scalable.

Use the GnuTLS psktool program to generate a keys.psk file containing one or more usernames and random keys:

     mkdir -m 0700 /tmp/keys
     psktool -u rich -p /tmp/keys/keys.psk

TLS-enabled servers such as qemu-nbd can use this directory like so:

     qemu-nbd \
       -t -x / \
       --object tls-creds-psk,id=tls0,endpoint=server,dir=/tmp/keys \
       --tls-creds tls0 \
       image.qcow2

When connecting from a qemu-based client you must specify the directory containing keys.psk and an optional USERNAME (defaults to ``qemu''):

     qemu-img info \
       --object tls-creds-psk,id=tls0,dir=/tmp/keys,username=rich,endpoint=client \
       --image-opts \
       file.driver=nbd,file.host=localhost,file.port=10809,file.tls-creds=tls0,file.export=/

GDB usage
=========

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

In order to use gdb, launch QEMU with the '-s' option. It will wait for a gdb connection:

     qemu-system-i386 -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
                         -append "root=/dev/hda"
     Connected to host network interface: tun0
     Waiting gdb connection on port 1234

Then launch gdb on the 'vmlinux' executable:

     > gdb vmlinux

In gdb, connect to QEMU:

     (gdb) target remote localhost:1234

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

     (gdb) c

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

 1. Use info reg to display all the CPU registers.

 2. Use x/10i $eip to display the code at the PC position.

 3. Use set architecture i8086 to dump 16 bit code. Then use x/10i $cs*16+$eip to dump the code at the PC position.

Advanced debugging options:

The default single stepping behavior is step with the IRQs and timer service routines off.  It is set this way because when gdb executes a single step it expects to advance beyond the current instruction.  With the IRQs and 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:

maintenance packet qqemu.sstepbits

     This will display the MASK bits used to control the single stepping IE:

          (gdb) maintenance packet qqemu.sstepbits
          sending: "qqemu.sstepbits"
          received: "ENABLE=1,NOIRQ=2,NOTIMER=4"

maintenance packet qqemu.sstep

     This will display the current value of the mask used when single stepping IE:

          (gdb) maintenance packet qqemu.sstep
          sending: "qqemu.sstep"
          received: "0x7"

maintenance packet Qqemu.sstep=HEX_VALUE

     This will change the single step mask, so if wanted to enable IRQs on the single step, but not timers, you would use:

          (gdb) maintenance packet Qqemu.sstep=0x5
          sending: "qemu.sstep=0x5"
          received: "OK"

Target OS specific information
==============================

Linux
-----

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

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

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

Windows
-------

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

SVGA graphic modes support
..........................

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

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

CPU usage reduction
...................

Windows 9x does not correctly use the CPU HLT instruction. The result is that it takes host CPU cycles even when idle. You can install the utility from https://web.archive.org/web/20060212132151/http://www.user.cityline.ru/~maxamn/amnhltm.zip to solve this problem. Note that no such tool is needed for NT, 2000 or XP.

Windows 2000 disk full problem
..............................

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

Windows 2000 shutdown
.....................

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

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

Share a directory between Unix and Windows
..........................................

See sec_invocation about the help of the option '-netdev user,smb=...'.

Windows XP security problem
...........................

Some releases of Windows XP install correctly but give a security error when booting:

     A problem is preventing Windows from accurately checking the
     license for this computer. Error code: 0x800703e6.

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

MS-DOS and FreeDOS
------------------

CPU usage reduction
...................

DOS does not correctly use the CPU HLT instruction. The result is that it takes host CPU cycles even when idle. You can install the utility from https://web.archive.org/web/20051222085335/http://www.vmware.com/software/dosidle210.zip to solve this problem.

QEMU System emulator for non PC targets
***************************************

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

PowerPC System emulator
=======================

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

QEMU emulates the following PowerMac peripherals:

  - UniNorth or Grackle PCI Bridge

  - PCI VGA compatible card with VESA Bochs Extensions

  - 2 PMAC IDE interfaces with hard disk and CD-ROM support

  - NE2000 PCI adapters

  - Non Volatile RAM

  - VIA-CUDA with ADB keyboard and mouse.

QEMU emulates the following PREP peripherals:

  - PCI Bridge

  - PCI VGA compatible card with VESA Bochs Extensions

  - 2 IDE interfaces with hard disk and CD-ROM support

  - Floppy disk

  - NE2000 network adapters

  - Serial port

  - PREP Non Volatile RAM

  - PC compatible keyboard and mouse.

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

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

The following options are specific to the PowerPC emulation:

-g WxH[xDEPTH]

     Set the initial VGA graphic mode. The default is 800x600x32.

-prom-env STRING

     Set OpenBIOS variables in NVRAM, for example:

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

     These variables are not used by Open Hack'Ware.

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

Sparc32 System emulator
=======================

Use the executable qemu-system-sparc to simulate the following Sun4m architecture machines:

  - SPARCstation 4

  - SPARCstation 5

  - SPARCstation 10

  - SPARCstation 20

  - SPARCserver 600MP

  - SPARCstation LX

  - SPARCstation Voyager

  - SPARCclassic

  - SPARCbook

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

QEMU emulates the following sun4m peripherals:

  - IOMMU

  - TCX or cgthree Frame buffer

  - Lance (Am7990) Ethernet

  - Non Volatile RAM M48T02/M48T08

  - Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboard and power/reset logic

  - ESP SCSI controller with hard disk and CD-ROM support

  - Floppy drive (not on SS-600MP)

  - CS4231 sound device (only on SS-5, not working yet)

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

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

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

The following options are specific to the Sparc32 emulation:

-g WxHx[xDEPTH]

     Set the initial graphics mode. For TCX, the default is 1024x768x8 with the option of 1024x768x24. For cgthree, the default is 1024x768x8 with the option of 1152x900x8 for people who wish to use OBP.

-prom-env STRING

     Set OpenBIOS variables in NVRAM, for example:

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

-M [SS-4|SS-5|SS-10|SS-20|SS-600MP|LX|Voyager|SPARCClassic] [|SPARCbook]

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

Sparc64 System emulator
=======================

Use the executable qemu-system-sparc64 to simulate a Sun4u (UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic Niagara (T1) machine. The Sun4u emulator is mostly complete, being able to run Linux, NetBSD and OpenBSD in headless (-nographic) mode. The Sun4v emulator is still a work in progress.

The Niagara T1 emulator makes use of firmware and OS binaries supplied in the S10image/ directory of the OpenSPARC T1 project http://download.oracle.com/technetwork/systems/opensparc/OpenSPARCT1_Arch.1.5.tar.bz2 and is able to boot the disk.s10hw2 Solaris image.

     qemu-system-sparc64 -M niagara -L /path-to/S10image/ \
                         -nographic -m 256 \
                         -drive if=pflash,readonly=on,file=/S10image/disk.s10hw2

QEMU emulates the following peripherals:

  - UltraSparc IIi APB PCI Bridge

  - PCI VGA compatible card with VESA Bochs Extensions

  - PS/2 mouse and keyboard

  - Non Volatile RAM M48T59

  - PC-compatible serial ports

  - 2 PCI IDE interfaces with hard disk and CD-ROM support

  - Floppy disk

The following options are specific to the Sparc64 emulation:

-prom-env STRING

     Set OpenBIOS variables in NVRAM, for example:

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

-M [sun4u|sun4v|niagara]

     Set the emulated machine type. The default is sun4u.

MIPS System emulator
====================

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

  - A generic ISA PC-like machine "mips"

  - The MIPS Malta prototype board "malta"

  - An ACER Pica "pica61". This machine needs the 64-bit emulator.

  - MIPS emulator pseudo board "mipssim"

  - A MIPS Magnum R4000 machine "magnum". This machine needs the 64-bit emulator.

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

  - A range of MIPS CPUs, default is the 24Kf

  - PC style serial port

  - PC style IDE disk

  - NE2000 network card

The Malta emulation supports the following devices:

  - Core board with MIPS 24Kf CPU and Galileo system controller

  - PIIX4 PCI/USB/SMbus controller

  - The Multi-I/O chip's serial device

  - PCI network cards (PCnet32 and others)

  - Malta FPGA serial device

  - Cirrus (default) or any other PCI VGA graphics card

The ACER Pica emulation supports:

  - MIPS R4000 CPU

  - PC-style IRQ and DMA controllers

  - PC Keyboard

  - IDE controller

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

  - A range of MIPS CPUs, default is the 24Kf

  - PC style serial port

  - MIPSnet network emulation

The MIPS Magnum R4000 emulation supports:

  - MIPS R4000 CPU

  - PC-style IRQ controller

  - PC Keyboard

  - SCSI controller

  - G364 framebuffer

nanoMIPS System emulator
------------------------

Executable qemu-system-mipsel also covers simulation of 32-bit nanoMIPS system in little endian mode:

  - nanoMIPS I7200 CPU

Example of qemu-system-mipsel usage for nanoMIPS is shown below:

Download <disk_image_file> from https://mipsdistros.mips.com/LinuxDistro/nanomips/buildroot/index.html.

Download <kernel_image_file> from https://mipsdistros.mips.com/LinuxDistro/nanomips/kernels/v4.15.18-432-gb2eb9a8b07a1-20180627102142/index.html.

Start system emulation of Malta board with nanoMIPS I7200 CPU:

     qemu-system-mipsel -cpu I7200 -kernel <kernel_image_file> \
         -M malta -serial stdio -m <memory_size> -hda <disk_image_file> \
         -append "mem=256m@0x0 rw console=ttyS0 vga=cirrus vesa=0x111 root=/dev/sda"

ARM System emulator
===================

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

  - ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU

  - Two PL011 UARTs

  - SMC 91c111 Ethernet adapter

  - PL110 LCD controller

  - PL050 KMI with PS/2 keyboard and mouse.

  - PL181 MultiMedia Card Interface with SD card.

The ARM Versatile baseboard is emulated with the following devices:

  - ARM926E, ARM1136 or Cortex-A8 CPU

  - PL190 Vectored Interrupt Controller

  - Four PL011 UARTs

  - SMC 91c111 Ethernet adapter

  - PL110 LCD controller

  - PL050 KMI with PS/2 keyboard and mouse.

  - PCI host bridge.  Note the emulated PCI bridge only provides access to PCI memory space.  It does not provide access to PCI IO space. This means some devices (eg. ne2k_pci NIC) are not usable, and others (eg. rtl8139 NIC) are only usable when the guest drivers use the memory mapped control registers.

  - PCI OHCI USB controller.

  - LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices.

  - PL181 MultiMedia Card Interface with SD card.

Several variants of the ARM RealView baseboard are emulated, including the EB, PB-A8 and PBX-A9.  Due to interactions with the bootloader, only certain Linux kernel configurations work out of the box on these boards.

Kernels for the PB-A8 board should have CONFIG_REALVIEW_HIGH_PHYS_OFFSET enabled in the kernel, and expect 512M RAM.  Kernels for The PBX-A9 board should have CONFIG_SPARSEMEM enabled, CONFIG_REALVIEW_HIGH_PHYS_OFFSET disabled and expect 1024M RAM.

The following devices are emulated:

  - ARM926E, ARM1136, ARM11MPCore, Cortex-A8 or Cortex-A9 MPCore CPU

  - ARM AMBA Generic/Distributed Interrupt Controller

  - Four PL011 UARTs

  - SMC 91c111 or SMSC LAN9118 Ethernet adapter

  - PL110 LCD controller

  - PL050 KMI with PS/2 keyboard and mouse

  - PCI host bridge

  - PCI OHCI USB controller

  - LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices

  - PL181 MultiMedia Card Interface with SD card.

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

  - Intel PXA270 System-on-chip (ARM V5TE core)

  - NAND Flash memory

  - IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in "Akita"

  - On-chip OHCI USB controller

  - On-chip LCD controller

  - On-chip Real Time Clock

  - TI ADS7846 touchscreen controller on SSP bus

  - Maxim MAX1111 analog-digital converter on I^2C bus

  - GPIO-connected keyboard controller and LEDs

  - Secure Digital card connected to PXA MMC/SD host

  - Three on-chip UARTs

  - WM8750 audio CODEC on I^2C and I^2S busses

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

  - Texas Instruments OMAP310 System-on-chip (ARM 925T core)

  - ROM and RAM memories (ROM firmware image can be loaded with -option-rom)

  - On-chip LCD controller

  - On-chip Real Time Clock

  - TI TSC2102i touchscreen controller / analog-digital converter / Audio CODEC, connected through MicroWire and I^2S busses

  - GPIO-connected matrix keypad

  - Secure Digital card connected to OMAP MMC/SD host

  - Three on-chip UARTs

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

  - Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)

  - RAM and non-volatile OneNAND Flash memories

  - Display connected to EPSON remote framebuffer chip and OMAP on-chip display controller and a LS041y3 MIPI DBI-C controller

  - TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen controllers driven through SPI bus

  - National Semiconductor LM8323-controlled qwerty keyboard driven through I^2C bus

  - Secure Digital card connected to OMAP MMC/SD host

  - Three OMAP on-chip UARTs and on-chip STI debugging console

  - A Bluetooth(R) transceiver and HCI connected to an UART

  - Mentor Graphics "Inventra" dual-role USB controller embedded in a TI TUSB6010 chip - only USB host mode is supported

  - TI TMP105 temperature sensor driven through I^2C bus

  - TI TWL92230C power management companion with an RTC on I^2C bus

  - Nokia RETU and TAHVO multi-purpose chips with an RTC, connected through CBUS

The Luminary Micro Stellaris LM3S811EVB emulation includes the following devices:

  - Cortex-M3 CPU core.

  - 64k Flash and 8k SRAM.

  - Timers, UARTs, ADC and I^2C interface.

  - OSRAM Pictiva 96x16 OLED with SSD0303 controller on I^2C bus.

The Luminary Micro Stellaris LM3S6965EVB emulation includes the following devices:

  - Cortex-M3 CPU core.

  - 256k Flash and 64k SRAM.

  - Timers, UARTs, ADC, I^2C and SSI interfaces.

  - OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via SSI.

The Freecom MusicPal internet radio emulation includes the following elements:

  - Marvell MV88W8618 ARM core.

  - 32 MB RAM, 256 KB SRAM, 8 MB flash.

  - Up to 2 16550 UARTs

  - MV88W8xx8 Ethernet controller

  - MV88W8618 audio controller, WM8750 CODEC and mixer

  - 128×64 display with brightness control

  - 2 buttons, 2 navigation wheels with button function

The Siemens SX1 models v1 and v2 (default) basic emulation. The emulation includes the following elements:

  - Texas Instruments OMAP310 System-on-chip (ARM 925T core)

  - ROM and RAM memories (ROM firmware image can be loaded with -pflash) V1 1 Flash of 16MB and 1 Flash of 8MB V2 1 Flash of 32MB

  - On-chip LCD controller

  - On-chip Real Time Clock

  - Secure Digital card connected to OMAP MMC/SD host

  - Three on-chip UARTs

A Linux 2.6 test image is available on the QEMU web site. More information is available in the QEMU mailing-list archive.

The following options are specific to the ARM emulation:

-semihosting
     Enable semihosting syscall emulation.

     On ARM this implements the "Angel" interface.

     Note that this allows guest direct access to the host filesystem, so should only be used with trusted guest OS.

ColdFire System emulator
========================

Use the executable qemu-system-m68k to simulate a ColdFire machine. The emulator is able to boot a uClinux kernel.

The M5208EVB emulation includes the following devices:

  - MCF5208 ColdFire V2 Microprocessor (ISA A+ with EMAC).

  - Three Two on-chip UARTs.

  - Fast Ethernet Controller (FEC)

The AN5206 emulation includes the following devices:

  - MCF5206 ColdFire V2 Microprocessor.

  - Two on-chip UARTs.

The following options are specific to the ColdFire emulation:

-semihosting
     Enable semihosting syscall emulation.

     On M68K this implements the "ColdFire GDB" interface used by libgloss.

     Note that this allows guest direct access to the host filesystem, so should only be used with trusted guest OS.

Cris System emulator
====================

TODO

Microblaze System emulator
==========================

TODO

SH4 System emulator
===================

TODO

Xtensa System emulator
======================

Two executables cover simulation of both Xtensa endian options, qemu-system-xtensa and qemu-system-xtensaeb. Two different machine types are emulated:

  - Xtensa emulator pseudo board "sim"

  - Avnet LX60/LX110/LX200 board

The sim pseudo board emulation provides an environment similar to one provided by the proprietary Tensilica ISS. It supports:

  - A range of Xtensa CPUs, default is the DC232B

  - Console and filesystem access via semihosting calls

The Avnet LX60/LX110/LX200 emulation supports:

  - A range of Xtensa CPUs, default is the DC232B

  - 16550 UART

  - OpenCores 10/100 Mbps Ethernet MAC

The following options are specific to the Xtensa emulation:

-semihosting
     Enable semihosting syscall emulation.

     Xtensa semihosting provides basic file IO calls, such as open/read/write/seek/select. Tensilica baremetal libc for ISS and linux platform "sim" use this interface.

     Note that this allows guest direct access to the host filesystem, so should only be used with trusted guest OS.

QEMU Guest Agent invocation
***************************

     [file qemu-ga.texi not included]

QEMU User space emulator
************************

Supported Operating Systems
===========================

The following OS are supported in user space emulation:

  - Linux (referred as qemu-linux-user)

  - BSD (referred as qemu-bsd-user)

Features
========

QEMU user space emulation has the following notable features:

System call translation:
     QEMU includes a generic system call translator.  This means that the parameters of the system calls can be converted to fix endianness and 32/64-bit mismatches between hosts and targets. IOCTLs can be converted too.

POSIX signal handling:
     QEMU can redirect to the running program all signals coming from the host (such as SIGALRM), as well as synthesize signals from virtual CPU exceptions (for example SIGFPE when the program executes a division by zero).

     QEMU relies on the host kernel to emulate most signal system calls, for example to emulate the signal mask.  On Linux, QEMU supports both normal and real-time signals.

Threading:
     On Linux, QEMU can emulate the clone syscall and create a real host thread (with a separate virtual CPU) for each emulated thread. Note that not all targets currently emulate atomic operations correctly. x86 and ARM use a global lock in order to preserve their semantics.

QEMU was conceived so that ultimately it can emulate itself. Although it is not very useful, it is an important test to show the power of the emulator.

Linux User space emulator
=========================

Quick Start
-----------

In order to launch a Linux process, QEMU needs the process executable itself and all the target (x86) dynamic libraries used by it.

  * On x86, you can just try to launch any process by using the native libraries:

          qemu-i386 -L / /bin/ls

     -L / tells that the x86 dynamic linker must be searched with a / prefix.

  * Since QEMU is also a linux process, you can launch QEMU with QEMU (NOTE: you can only do that if you compiled QEMU from the sources):

          qemu-i386 -L / qemu-i386 -L / /bin/ls

  * On non x86 CPUs, you need first to download at least an x86 glibc (qemu-runtime-i386-XXX-.tar.gz on the QEMU web page). Ensure that LD_LIBRARY_PATH is not set:

          unset LD_LIBRARY_PATH

     Then you can launch the precompiled ls x86 executable:

          qemu-i386 tests/i386/ls

     You can look at scripts/qemu-binfmt-conf.sh so that QEMU is automatically launched by the Linux kernel when you try to launch x86 executables. It requires the binfmt_misc module in the Linux kernel.

  * The x86 version of QEMU is also included. You can try weird things such as:

          qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 \
                    /usr/local/qemu-i386/bin/ls-i386

Wine launch
-----------

  * Ensure that you have a working QEMU with the x86 glibc distribution (see previous section). In order to verify it, you must be able to do:

          qemu-i386 /usr/local/qemu-i386/bin/ls-i386

  * Download the binary x86 Wine install (qemu-XXX-i386-wine.tar.gz on the QEMU web page).

  * Configure Wine on your account. Look at the provided script /usr/local/qemu-i386/bin/wine-conf.sh. Your previous ${HOME}/.wine directory is saved to ${HOME}/.wine.org.

  * Then you can try the example putty.exe:

          qemu-i386 /usr/local/qemu-i386/wine/bin/wine \
                    /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe

Command line options
--------------------

     qemu-i386 [-h] [-d] [-L PATH] [-s SIZE] [-cpu MODEL] [-g PORT] [-B OFFSET] [-R SIZE] PROGRAM [ARGUMENTS...]

-h
     Print the help

-L path
     Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)

-s size
     Set the x86 stack size in bytes (default=524288)

-cpu model
     Select CPU model (-cpu help for list and additional feature selection)

-E VAR=VALUE
     Set environment VAR to VALUE.

-U VAR
     Remove VAR from the environment.

-B offset
     Offset guest address by the specified number of bytes.  This is useful when the address region required by guest applications is reserved on the host. This option is currently only supported on some hosts.

-R size
     Pre-allocate a guest virtual address space of the given size (in bytes). "G", "M", and "k" suffixes may be used when specifying the size.

Debug options:

-d item1,...
     Activate logging of the specified items (use '-d help' for a list of log items)

-p pagesize
     Act as if the host page size was 'pagesize' bytes

-g port
     Wait gdb connection to port

-singlestep
     Run the emulation in single step mode.

Environment variables:

QEMU_STRACE
     Print system calls and arguments similar to the 'strace' program (NOTE: the actual 'strace' program will not work because the user space emulator hasn't implemented ptrace).  At the moment this is incomplete.  All system calls that don't have a specific argument format are printed with information for six arguments.  Many flag-style arguments don't have decoders and will show up as numbers.

Other binaries
--------------

qemu-alpha TODO.

qemu-armeb TODO.

qemu-arm is also capable of running ARM "Angel" semihosted ELF binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB configurations), and arm-uclinux bFLT format binaries.

qemu-m68k is capable of running semihosted binaries using the BDM (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and coldfire uClinux bFLT format binaries.

The binary format is detected automatically.

qemu-cris TODO.

qemu-i386 TODO. qemu-x86_64 TODO.

qemu-microblaze TODO.

qemu-mips executes 32-bit big endian MIPS binaries (MIPS O32 ABI).

qemu-mipsel executes 32-bit little endian MIPS binaries (MIPS O32 ABI).

qemu-mips64 executes 64-bit big endian MIPS binaries (MIPS N64 ABI).

qemu-mips64el executes 64-bit little endian MIPS binaries (MIPS N64 ABI).

qemu-mipsn32 executes 32-bit big endian MIPS binaries (MIPS N32 ABI).

qemu-mipsn32el executes 32-bit little endian MIPS binaries (MIPS N32 ABI).

qemu-nios2 TODO.

qemu-ppc64abi32 TODO. qemu-ppc64 TODO. qemu-ppc TODO.

qemu-sh4eb TODO. qemu-sh4 TODO.

qemu-sparc can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).

qemu-sparc32plus can execute Sparc32 and SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).

qemu-sparc64 can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).

BSD User space emulator
=======================

BSD Status
----------

  - target Sparc64 on Sparc64: Some trivial programs work.

Quick Start
-----------

In order to launch a BSD process, QEMU needs the process executable itself and all the target dynamic libraries used by it.

  * On Sparc64, you can just try to launch any process by using the native libraries:

          qemu-sparc64 /bin/ls

Command line options
--------------------

     qemu-sparc64 [-h] [-d] [-L PATH] [-s SIZE] [-bsd TYPE] PROGRAM [ARGUMENTS...]

-h
     Print the help

-L path
     Set the library root path (default=/)

-s size
     Set the stack size in bytes (default=524288)

-ignore-environment
     Start with an empty environment. Without this option, the initial environment is a copy of the caller's environment.

-E VAR=VALUE
     Set environment VAR to VALUE.

-U VAR
     Remove VAR from the environment.

-bsd type
     Set the type of the emulated BSD Operating system. Valid values are FreeBSD, NetBSD and OpenBSD (default).

Debug options:

-d item1,...
     Activate logging of the specified items (use '-d help' for a list of log items)

-p pagesize
     Act as if the host page size was 'pagesize' bytes

-singlestep
     Run the emulation in single step mode.

System requirements
*******************

KVM kernel module
=================

On x86_64 hosts, the default set of CPU features enabled by the KVM accelerator require the host to be running Linux v4.5 or newer.

The OpteronG[345] CPU models require KVM support for RDTSCP, which was added with Linux 4.5 which is supported by the major distros. And even if RHEL7 has kernel 3.10, KVM there has the required functionality there to make it close to a 4.5 or newer kernel.

     [file qemu-tech.texi not included]

     [file qemu-deprecated.texi not included]

Supported build platforms
*************************

QEMU aims to support building and executing on multiple host OS platforms. This appendix outlines which platforms are the major build targets. These platforms are used as the basis for deciding upon the minimum required versions of 3rd party software QEMU depends on. The supported platforms are the targets for automated testing performed by the project when patches are submitted for review, and tested before and after merge.

If a platform is not listed here, it does not imply that QEMU won't work. If an unlisted platform has comparable software versions to a listed platform, there is every expectation that it will work. Bug reports are welcome for problems encountered on unlisted platforms unless they are clearly older vintage than what is described here.

Note that when considering software versions shipped in distros as support targets, QEMU considers only the version number, and assumes the features in that distro match the upstream release with the same version. In other words, if a distro backports extra features to the software in their distro, QEMU upstream code will not add explicit support for those backports, unless the feature is auto-detectable in a manner that works for the upstream releases too.

The Repology site https://repology.org is a useful resource to identify currently shipped versions of software in various operating systems, though it does not cover all distros listed below.

Linux OS
========

For distributions with frequent, short-lifetime releases, the project will aim to support all versions that are not end of life by their respective vendors. For the purposes of identifying supported software versions, the project will look at Fedora, Ubuntu, and openSUSE distros. Other short- lifetime distros will be assumed to ship similar software versions.

For distributions with long-lifetime releases, the project will aim to support the most recent major version at all times. Support for the previous major version will be dropped 2 years after the new major version is released. For the purposes of identifying supported software versions, the project will look at RHEL, Debian, Ubuntu LTS, and SLES distros. Other long-lifetime distros will be assumed to ship similar software versions.

Windows
=======

The project supports building with current versions of the MinGW toolchain, hosted on Linux.

macOS
=====

The project supports building with the two most recent versions of macOS, with the current homebrew package set available.

FreeBSD
=======

The project aims to support the all the versions which are not end of life.

NetBSD
======

The project aims to support the most recent major version at all times. Support for the previous major version will be dropped 2 years after the new major version is released.

OpenBSD
=======

The project aims to support the all the versions which are not end of life.

License
*******

QEMU is a trademark of Fabrice Bellard.

QEMU is released under the GNU General Public License (https://www.gnu.org/licenses/gpl-2.0.txt), version 2. Parts of QEMU have specific licenses, see file LICENSE (https://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE).

Index
*****

Concept Index
=============

This is the main index. Should we combine all keywords in one index? TODO

Function Index
==============

This index could be used for command line options and monitor functions.

Keystroke Index
===============

This is a list of all keystrokes which have a special function in system emulation.

Data Type Index
===============

This index could be used for qdev device names and options.