qemu-doc.texi

qemu性能直逼VMware的仿真器QEMU 的模擬速度約為實機的 25％；約為 Bochs 的 60 倍。Plex86、User-Mode-Linux、VMware 和 Virtual PC 則比

Debug/Expert options:
@table @option

@item -serial dev
Redirect the virtual serial port to host character device
@var{dev}. The default device is @code{vc} in graphical mode and
@code{stdio} in non graphical mode.

This option can be used several times to simulate up to 4 serials
ports.

Use @code{-serial none} to disable all serial ports.

Available character devices are:
@table @code
@item vc
Virtual console
@item pty
[Linux only] Pseudo TTY (a new PTY is automatically allocated)
@item none
No device is allocated.
@item null
void device
@item /dev/XXX
[Linux only] Use host tty, e.g. @file{/dev/ttyS0}. The host serial port
parameters are set according to the emulated ones.
@item /dev/parportN
[Linux only, parallel port only] Use host parallel port
@var{N}. Currently only SPP parallel port features can be used.
@item file:filename
Write output to filename. No character can be read.
@item stdio
[Unix only] standard input/output
@item pipe:filename
name pipe @var{filename}
@item COMn
[Windows only] Use host serial port @var{n}
@item udp:[remote_host]:remote_port[@@[src_ip]:src_port]
This implements UDP Net Console.  When @var{remote_host} or @var{src_ip} are not specified they default to @code{0.0.0.0}.  When not using a specifed @var{src_port} a random port is automatically chosen.

If you just want a simple readonly console you can use @code{netcat} or
@code{nc}, by starting qemu with: @code{-serial udp::4555} and nc as:
@code{nc -u -l -p 4555}. Any time qemu writes something to that port it
will appear in the netconsole session.

If you plan to send characters back via netconsole or you want to stop
and start qemu a lot of times, you should have qemu use the same
source port each time by using something like @code{-serial
udp::4555@@:4556} to qemu. Another approach is to use a patched
version of netcat which can listen to a TCP port and send and receive
characters via udp.  If you have a patched version of netcat which
activates telnet remote echo and single char transfer, then you can
use the following options to step up a netcat redirector to allow
telnet on port 5555 to access the qemu port.
@table @code
@item Qemu Options:
-serial udp::4555@@:4556
@item netcat options:
-u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
@item telnet options:
localhost 5555
@end table


@item tcp:[host]:port[,server][,nowait][,nodelay]
The TCP Net Console has two modes of operation.  It can send the serial
I/O to a location or wait for a connection from a location.  By default
the TCP Net Console is sent to @var{host} at the @var{port}.  If you use
the @var{server} option QEMU will wait for a client socket application
to connect to the port before continuing, unless the @code{nowait}
option was specified.  The @code{nodelay} option disables the Nagle buffering
algoritm.  If @var{host} is omitted, 0.0.0.0 is assumed. Only
one TCP connection at a time is accepted. You can use @code{telnet} to
connect to the corresponding character device.
@table @code
@item Example to send tcp console to 192.168.0.2 port 4444
-serial tcp:192.168.0.2:4444
@item Example to listen and wait on port 4444 for connection
-serial tcp::4444,server
@item Example to not wait and listen on ip 192.168.0.100 port 4444
-serial tcp:192.168.0.100:4444,server,nowait
@end table

@item telnet:host:port[,server][,nowait][,nodelay]
The telnet protocol is used instead of raw tcp sockets.  The options
work the same as if you had specified @code{-serial tcp}.  The
difference is that the port acts like a telnet server or client using
telnet option negotiation.  This will also allow you to send the
MAGIC_SYSRQ sequence if you use a telnet that supports sending the break
sequence.  Typically in unix telnet you do it with Control-] and then
type "send break" followed by pressing the enter key.

@item unix:path[,server][,nowait]
A unix domain socket is used instead of a tcp socket.  The option works the
same as if you had specified @code{-serial tcp} except the unix domain socket
@var{path} is used for connections.

@end table

@item -parallel dev
Redirect the virtual parallel port to host device @var{dev} (same
devices as the serial port). On Linux hosts, @file{/dev/parportN} can
be used to use hardware devices connected on the corresponding host
parallel port.

This option can be used several times to simulate up to 3 parallel
ports.

Use @code{-parallel none} to disable all parallel ports.

@item -monitor dev
Redirect the monitor to host device @var{dev} (same devices as the
serial port).
The default device is @code{vc} in graphical mode and @code{stdio} in
non graphical mode.

@item -s
Wait gdb connection to port 1234 (@pxref{gdb_usage}). 
@item -p port
Change gdb connection port.  @var{port} can be either a decimal number
to specify a TCP port, or a host device (same devices as the serial port).
@item -S
Do not start CPU at startup (you must type 'c' in the monitor).
@item -d             
Output log in /tmp/qemu.log
@item -hdachs c,h,s,[,t]
Force hard disk 0 physical geometry (1 <= @var{c} <= 16383, 1 <=
@var{h} <= 16, 1 <= @var{s} <= 63) and optionally force the BIOS
translation mode (@var{t}=none, lba or auto). Usually QEMU can guess
all thoses parameters. This option is useful for old MS-DOS disk
images.

@item -L path
Set the directory for the BIOS, VGA BIOS and keymaps.

@item -std-vga
Simulate a standard VGA card with Bochs VBE extensions (default is
Cirrus Logic GD5446 PCI VGA). If your guest OS supports the VESA 2.0
VBE extensions (e.g. Windows XP) and if you want to use high
resolution modes (>= 1280x1024x16) then you should use this option.

@item -no-acpi
Disable ACPI (Advanced Configuration and Power Interface) support. Use
it if your guest OS complains about ACPI problems (PC target machine
only).

@item -no-reboot
Exit instead of rebooting.

@item -loadvm file
Start right away with a saved state (@code{loadvm} in monitor)

@item -semihosting
Enable "Angel" semihosting interface (ARM target machines only).
Note that this allows guest direct access to the host filesystem,
so should only be used with trusted guest OS.
@end table

@c man end

@node pcsys_keys
@section Keys

@c man begin OPTIONS

During the graphical emulation, you can use the following keys:
@table @key
@item Ctrl-Alt-f
Toggle full screen

@item Ctrl-Alt-n
Switch to virtual console 'n'. Standard console mappings are:
@table @emph
@item 1
Target system display
@item 2
Monitor
@item 3
Serial port
@end table

@item Ctrl-Alt
Toggle mouse and keyboard grab.
@end table

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

During emulation, if you are using the @option{-nographic} option, use
@key{Ctrl-a h} to get terminal commands:

@table @key
@item Ctrl-a h
Print this help
@item Ctrl-a x    
Exit emulator
@item Ctrl-a s    
Save disk data back to file (if -snapshot)
@item Ctrl-a b
Send break (magic sysrq in Linux)
@item Ctrl-a c
Switch between console and monitor
@item Ctrl-a Ctrl-a
Send Ctrl-a
@end table
@c man end

@ignore

@c man begin SEEALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
@c man end

@c man begin AUTHOR
Fabrice Bellard
@c man end

@end ignore

@node pcsys_monitor
@section QEMU Monitor

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

@itemize @minus

@item
Remove or insert removable medias images
(such as CD-ROM or floppies)

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

@item Inspect the VM state without an external debugger.

@end itemize

@subsection Commands

The following commands are available:

@table @option

@item help or ? [cmd]
Show the help for all commands or just for command @var{cmd}.

@item commit  
Commit changes to the disk images (if -snapshot is used)

@item info subcommand 
show various information about the system state

@table @option
@item info network
show the various VLANs and the associated devices
@item info block
show the block devices
@item info registers
show the cpu registers
@item info history
show the command line history
@item info pci
show emulated PCI device
@item info usb
show USB devices plugged on the virtual USB hub
@item info usbhost
show all USB host devices
@item info capture
show information about active capturing
@item info snapshots
show list of VM snapshots
@item info mice
show which guest mouse is receiving events
@end table

@item q or quit
Quit the emulator.

@item eject [-f] device
Eject a removable media (use -f to force it).

@item change device filename
Change a removable media.

@item screendump filename
Save screen into PPM image @var{filename}.

@item mouse_move dx dy [dz]
Move the active mouse to the specified coordinates @var{dx} @var{dy}
with optional scroll axis @var{dz}.

@item mouse_button val
Change the active mouse button state @var{val} (1=L, 2=M, 4=R).

@item mouse_set index
Set which mouse device receives events at given @var{index}, index
can be obtained with
@example
info mice
@end example

@item wavcapture filename [frequency [bits [channels]]]
Capture audio into @var{filename}. Using sample rate @var{frequency}
bits per sample @var{bits} and number of channels @var{channels}.

Defaults:
@itemize @minus
@item Sample rate = 44100 Hz - CD quality
@item Bits = 16
@item Number of channels = 2 - Stereo
@end itemize

@item stopcapture index
Stop capture with a given @var{index}, index can be obtained with
@example
info capture
@end example

@item log item1[,...]
Activate logging of the specified items to @file{/tmp/qemu.log}.

@item savevm [tag|id]
Create a snapshot of the whole virtual machine. If @var{tag} is
provided, it is used as human readable identifier. If there is already
a snapshot with the same tag or ID, it is replaced. More info at
@ref{vm_snapshots}.

@item loadvm tag|id
Set the whole virtual machine to the snapshot identified by the tag
@var{tag} or the unique snapshot ID @var{id}.

@item delvm tag|id
Delete the snapshot identified by @var{tag} or @var{id}.

@item stop
Stop emulation.

@item c or cont
Resume emulation.

@item gdbserver [port]
Start gdbserver session (default port=1234)

@item x/fmt addr
Virtual memory dump starting at @var{addr}.

@item xp /fmt addr
Physical memory dump starting at @var{addr}.

@var{fmt} is a format which tells the command how to format the
data. Its syntax is: @option{/@{count@}@{format@}@{size@}}

@table @var
@item count 
is the number of items to be dumped.

@item format
can be x (hexa), d (signed decimal), u (unsigned decimal), o (octal),
c (char) or i (asm instruction).

@item size
can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits). On x86,
@code{h} or @code{w} can be specified with the @code{i} format to
respectively select 16 or 32 bit code instruction size.

@end table

Examples: 
@itemize
@item
Dump 10 instructions at the current instruction pointer:
@example 
(qemu) x/10i $eip
0x90107063:  ret
0x90107064:  sti
0x90107065:  lea    0x0(%esi,1),%esi
0x90107069:  lea    0x0(%edi,1),%edi
0x90107070:  ret
0x90107071:  jmp    0x90107080
0x90107073:  nop
0x90107074:  nop
0x90107075:  nop
0x90107076:  nop
@end example

@item
Dump 80 16 bit values at the start of the video memory.
@smallexample 
(qemu) xp/80hx 0xb8000
0x000b8000: 0x0b50 0x0b6c 0x0b65 0x0b78 0x0b38 0x0b36 0x0b2f 0x0b42
0x000b8010: 0x0b6f 0x0b63 0x0b68 0x0b73 0x0b20 0x0b56 0x0b47 0x0b41
0x000b8020: 0x0b42 0x0b69 0x0b6f 0x0b73 0x0b20 0x0b63 0x0b75 0x0b72
0x000b8030: 0x0b72 0x0b65 0x0b6e 0x0b74 0x0b2d 0x0b63 0x0b76 0x0b73
0x000b8040: 0x0b20 0x0b30 0x0b35 0x0b20 0x0b4e 0x0b6f 0x0b76 0x0b20
0x000b8050: 0x0b32 0x0b30 0x0b30 0x0b33 0x0720 0x0720 0x0720 0x0720
0x000b8060: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8070: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8080: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8090: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
@end smallexample
@end itemize

@item p or print/fmt expr

Print expression value. Only the @var{format} part of @var{fmt} is
used.

@item sendkey keys

Send @var{keys} to the emulator. Use @code{-} to press several keys
simultaneously. Example:
@example
sendkey ctrl-alt-f1
@end example

This command is useful to send keys that your graphical user interface
intercepts at low level, such as @code{ctrl-alt-f1} in X Window.

@item system_reset

Reset the system.

@item usb_add devname

Add the USB device @var{devname}.  For details of available devices see
@ref{usb_devices}

@item usb_del devname

Remove the USB device @var{devname} from the QEMU virtual USB
hub. @var{devname} has the syntax @code{bus.addr}. Use the monitor
command @code{info usb} to see the devices you can remove.

@end table

@subsection Integer expressions

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

@node disk_images
@section Disk Images

Since version 0.6.1, QEMU supports many disk image formats, including
growable disk images (their size increase as non empty sectors are
written), compressed and encrypted disk images. Version 0.8.3 added
the new qcow2 disk image format which is essential to support VM
snapshots.

@menu
* disk_images_quickstart::    Quick start for disk image creation
* disk_images_snapshot_mode:: Snapshot mode
* vm_snapshots::              VM snapshots
* qemu_img_invocation::       qemu-img Invocation
* host_drives::               Using host drives
* disk_images_fat_images::    Virtual FAT disk images
@end menu

@node disk_images_quickstart
@subsection Quick start for disk image creation

You can create a disk image with the command:
@example
qemu-img create myimage.img mysize
@end example
where @var{myimage.img} is the disk image filename and @var{mysize} is its
size in kilobytes. You can add an @code{M} suffix to give the size in
megabytes and a @code{G} suffix for gigabytes.

See @ref{qemu_img_invocation} for more information.

@node disk_images_snapshot_mode
@subsection Snapshot mode

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

@node vm_snapshots
@subsection VM snapshots

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

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

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

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

A VM snapshot is made of a VM state info (its size is shown in
@code{info snapshots}) and a snapshot of every writable disk image.
The VM state info is stored in the first @code{qcow2} non removable
and writable block device. The disk image snapshots are stored in