Provided by: bochs_2.3.7-1ubuntu1_i386
bochsrc - Configuration file for Bochs.
Bochsrc is the configuration file that specifies where Bochs
should look for disk images, how the Bochs emulation layer should
work, etc. The syntax used for bochsrc can also be used as
command line arguments for Bochs. The .bochsrc file should be placed
either in the current directory before running Bochs or in your home
Starting with Bochs 1.3, you can use environment variables in the
bochsrc file, for example:
floppya: 1_44="$IMAGES/bootdisk.img", status=inserted
Starting with version 2.0, two environment variables have a built-in
default value which is set at compile time. $BXSHARE points to the
"share" directory which is typically /usr/local/share/bochs on UNIX
machines. See the $(sharedir) variable in the Makefile for the exact
value. $BXSHARE is used by disk images to locate the directory where
the BIOS images and keymaps can be found. If $BXSHARE is not defined,
Bochs will supply the default value. Also, $LTDL_LIBRARY_PATH points
to a list of directories (separated by colons if more than one) to
search in for Bochs plugins. A compile-time default is provided if
this variable is not defined by the user.
This option includes another configuration file. It is possible
to put installation defaults in a global config file (e.g.
location of rom images).
The configuration interface is a series of menus or dialog boxes
that allows you to change all the settings that control Bochs’s
behavior. There are two choices of configuration interface: a
text mode version called "textconfig" and a graphical version
called "wx". The text mode version uses stdin/stdout and is
always compiled in. The graphical version is only available
when you use "--with-wx" on the configure command. If you do
not write a config_interface line, Bochs will choose a default
NOTE: if you use the "wx" configuration interface, you must also
use the "wx" display library.
The display library is the code that displays the Bochs VGA
screen. Bochs has a selection of about 10 different display
library implementations for different platforms. If you run
configure with multiple --with-* options, the display_library
command lets you choose which one you want to run with. If you
do not write a display_library line, Bochs will choose a default
The choices are:
x X windows interface, cross platform
win32 native win32 libraries
carbon Carbon library (for MacOS X)
beos native BeOS libraries
macintosh MacOS pre-10
amigaos native AmigaOS libraries
sdl SDL library, cross platform
term text only, uses curses/ncurses library, cross
rfb provides an interface to AT&T’s VNC viewer, cross
wx wxWidgets library, cross platform
nogui no display at all
Some display libraries now support specific option to control
their behaviour. See the examples below for currently supported
NOTE: if you use the "wx" configuration interface, you must also
use the "wx" display library.
display_library: rfb, options="timeout=60" # time to wait for
display_library: sdl, options="fullscreen" # startup in
display_library: x, options="hideIPS" # disable IPS output in
The ROM BIOS controls what the PC does when it first powers on.
Normally, you can use a precompiled BIOS in the source or binary
distribution called BIOS-bochs-latest. The default ROM BIOS is
usually loaded starting at address 0xe0000, and it is exactly
128k long. The legacy version of the Bochs BIOS is usually
loaded starting at address 0xf0000, and it is exactly 64k long.
You can also use the environment variable $BXSHARE to specify
the location of the BIOS. The usage of external large BIOS
images (up to 512k) at memory top is now supported, but we still
recommend to use the BIOS distributed with Bochs. The start
address is optional, since it can be calculated from image size.
romimage: file=mybios.bin, address=0xfff80000
cpu: This defines cpu-related parameters inside Bochs:
Set the number of processors:cores per processor:threads per
core when Bochs is compiled for SMP emulation. Bochs currently
supports up to 8 processors. If Bochs is compiled without SMP
support, it won’t accept values different from 1.
Maximum amount of instructions allowed to execute by processor
before returning control to another cpu. This option exists only
in Bochs binary compiled with SMP support.
Reset the CPU when triple fault occur (highly recommended)
rather than PANIC. Remember that if you trying to continue after
triple fault the simulation will be completely bogus !
Emulated Instructions Per Second. This is the number of IPS
that Bochs is capable of running on your machine. You can
recompile Bochs with --enable-show-ips option enabled, to find
your workstation’s capability. Measured IPS value will then be
logged into your log file or status bar (if supported by the
IPS is used to calibrate many time-dependent events within
the bochs simulation. For example, changing IPS affects the
frequency of VGA updates, the duration of time before a key
starts to autorepeat, and the measurement of BogoMips and
Bochs Machine/Compiler Mips
2.3.7 3.2Ghz Intel Core 2 Q9770 with WinXP/g++ 3.4 50 to 55 Mips
2.3.7 2.6Ghz Intel Core 2 Duo with WinXP/g++ 3.4 38 to 43 Mips
2.2.6 2.6Ghz Intel Core 2 Duo with WinXP/g++ 3.4 21 to 25 Mips
2.2.6 2.1Ghz Athlon XP with Linux 2.6/g++ 3.4 12 to 15 Mips
2.0.1 1.6Ghz Intel P4 with Win2000/g++ 3.3 5 to 7 Mips
 IPS measurements depend on OS and compiler configuration
in addition to processor clock speed.
cpu: count=2, ips=10000000
megs: Set the number of Megabytes of physical memory you want to
emulate. The default is 32MB, most OS’s won’t need more than
that. The maximum amount of memory supported is 2048Mb.
optromimage1: , optromimage2: , optromimage3: or optromimage4:
You may now load up to 4 optional ROM images. Be sure to use a
read-only area, typically between C8000 and EFFFF. These
optional ROM images should not overwrite the rombios (located at
F0000-FFFFF) and the videobios (located at C0000-C7FFF). Those
ROM images will be initialized by the bios if they contain the
right signature (0x55AA). It can also be a convenient way to
upload some arbitrary code/data in the simulation, that can be
retrieved by the boot loader
optromimage1: file=optionalrom.bin, address=0xd0000
You also need to load a VGA ROM BIOS into 0xC0000.
vga: Here you can specify the display extension to be used. With the
value ’none’ you can use standard VGA with no extension. Other
supported values are ’vbe’ for Bochs VBE and ’cirrus’ for Cirrus
floppya: or floppyb:
Point this to the pathname of a floppy image file or device.
Floppya is the first drive, and floppyb is the second drive.
If you’re booting from a floppy, floppya should point to a
You can set the initial status of the media to ’ejected’ or
’inserted’. Usually you will want to use ’inserted’.
2.88M 3.5" Floppy:
floppya: 2_88=path, status=ejected
1.44M 3.5" Floppy:
floppya: 1_44=path, status=inserted
1.2M 5.25" Floppy:
floppyb: 1_2=path, status=ejected
720K 3.5" Floppy:
floppya: 720k=path, status=inserted
360K 5.25" Floppy:
floppya: 360k=path, status=inserted
Autodetect Floppy type:
floppya: image=path, status=inserted
ata0: , ata1: , ata2: or ata3:
These options enables up to 4 ata channels. For each channel the
two base io addresses and the irq must be specified. ata0 and
ata1 are enabled by default, with the values shown below.
ata0: enabled=1, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
ata1: enabled=1, ioaddr1=0x170, ioaddr2=0x370, irq=15
ata2: enabled=1, ioaddr1=0x1e8, ioaddr2=0x3e0, irq=11
ata3: enabled=1, ioaddr1=0x168, ioaddr2=0x360, irq=9
ata[0-3]-master: or ata[0-3]-slave:
This defines the type and characteristics of all attached ata
type= type of attached device [disk|cdrom]
path= path of the image
mode= image mode
only valid for disks
cylinders= only valid for disks
heads= only valid for disks
spt= only valid for disks
status= only valid for cdroms [inserted|ejected]
biosdetect= type of biosdetection [none|auto], only for disks
on ata0 [cmos]
translation=type of translation of the bios, only for disks
model= string returned by identify device command
journal= optional filename of the redolog for undoable and
Point this at a hard disk image file, cdrom iso file, or a
physical cdrom device. To create a hard disk image, try running
bximage. It will help you choose the size and then suggest a
line that works with it.
In UNIX it is possible to use a raw device as a Bochs hard disk,
but WE DON’T RECOMMEND IT.
The path is always mandatory. Disk geometry autodetection works
with images created by bximage if CHS is set to 0/0/0 (cylinders
are calculated using heads=16 and spt=63). For other hard disk
images and modes the cylinders, heads, and spt are mandatory.
The mode option defines how the disk image is handled. Disks can
be defined as:
- flat : one file flat layout
- concat : multiple files layout
- external : developer’s specific, through a C++ class
- dll : developer’s specific, through a DLL
- sparse : stackable, commitable, rollbackable
- vmware3 : vmware3 disk support
- undoable : flat file with commitable redolog
- growing : growing file
- volatile : flat file with volatile redolog
The disk translation scheme (implemented in legacy int13 bios
functions, and used by older operating systems like MS-DOS), can
be defined as:
- none : no translation, for disks up to 528MB (1032192
- large : a standard bitshift algorithm, for disks up to 4.2GB
- rechs : a revised bitshift algorithm, using a 15 heads fake
physical geometry, for disks up to 7.9GB (15482880 sectors).
(don’t use this unless you understand what you’re doing)
- lba : a standard lba-assisted algorithm, for disks up to
8.4GB (16450560 sectors)
- auto : autoselection of best translation scheme. (it should
be changed if system does not boot)
Default values are:
mode=flat, biosdetect=auto, translation=auto, model="Generic
The biosdetect option has currently no effect on the bios
ata0-master: type=disk, path=10M.sample, cylinders=306,
ata0-slave: type=disk, path=20M.sample, cylinders=615,
ata1-master: type=disk, path=30M.sample, cylinders=615,
ata1-slave: type=disk, path=46M.sample, cylinders=940,
ata2-master: type=disk, path=62M.sample, cylinders=940,
ata2-slave: type=disk, path=112M.sample, cylinders=900,
ata3-master: type=disk, path=483M.sample, cylinders=1024,
ata3-slave: type=cdrom, path=iso.sample, status=inserted
com1: , com2: , com3: or com4:
This defines a serial port (UART type 16550A). In the ’term’ you
can specify a device to use as com1. This can be a real serial
line, or a pty. To use a pty (under X/Unix), create two windows
(xterms, usually). One of them will run bochs, and the other
will act as com1. Find out the tty the com1 window using the
‘tty’ command, and use that as the ‘dev’ parameter. Then do
‘sleep 1000000’ in the com1 window to keep the shell from
messing with things, and run bochs in the other window. Serial
I/O to com1 (port 0x3f8) will all go to the other window.
Other serial modes are ’null’ (no input/output), ’file’ (output
to a file specified as the ’dev’ parameter), ’raw’ (use the real
serial port - under construction for win32) and ’mouse’
(standard serial mouse - requires mouse option setting
’type=serial’ or ’type=serial_wheel’)
com1: enabled=term, dev=/dev/ttyp7
com2: enabled=1, mode=file, dev=serial.out
com1: enabled=1, mode=mouse
parport1: or parport2:
This defines a parallel (printer) port. When turned on and an
output file is defined the emulated printer port sends
characters printed by the guest OS into the output file. On some
platforms a device filename can be used to send the data to the
real parallel port (e.g. "/dev/lp0" on Linux).
parport1: enabled=1, file=parport.out
parport2: enabled=1, file="/dev/lp0"
boot: This defines the boot sequence. Now you can specify up to 3 boot
drives, which can be ’floppy’, ’disk’, ’cdrom’ or ’network’
(boot ROM). Legacy ’a’ and ’c’ are also supported.
boot: cdrom, floppy, disk
This disables the 0xaa55 signature check on boot floppies The
check is enabled by default.
log: Give the path of the log file you’d like Bochs debug and misc.
verbiage to be written to. If you really don’t want it, make
log: /dev/tty (unix only)
log: /dev/null (unix only)
This handles the format of the string prepended to each log line
: You may use those special tokens :
%t : 11 decimal digits timer tick
%i : 8 hexadecimal digits of cpu0 current eip
%e : 1 character event type (’i’nfo, ’d’ebug, ’p’anic,
%d : 5 characters string of the device, between brackets
Default : %t%e%d
panic: If Bochs reaches a condition where it cannot emulate
correctly, it does a panic. This can be a configuration
problem (like a misspelled bochsrc line) or an emulation
problem (like an unsupported video mode). The "panic" setting
in bochsrc tells Bochs how to respond to a panic. You can
set this to fatal (terminate the session), report (print
information to the console), or ignore (do nothing).
The safest setting is action=fatal. If you are getting panics,
you can try action=report instead. If you allow Bochs to
continue after a panic, don’t be surprised if you get strange
behavior or crashes if a panic occurs. Please report panic
messages unless it is just a configuration problem like
"could not find hard drive image."
error: Bochs produces an error message when it finds a condition that
really shouldn’t happen, but doesn’t endanger the simulation.
An example of an error might be if the emulated software
produces an illegal disk command.
The "error" setting tells Bochs how to respond to an error
condition. You can set this to fatal (terminate the
session), report (print information to the console), or
ignore (do nothing).
info: This setting tells Bochs what to do when an event occurs
that generates informational messages. You can set this to
fatal (that would not be very smart though), report (print
information to the console), or ignore (do nothing). For
general usage, the "report" option is probably a good choice.
debug: This setting tells Bochs what to do with messages intended
to assist in debugging. You can set this to fatal (but you
shouldn’t), report (print information to the console), or
ignore (do nothing). You should generally set this to ignore,
unless you are trying to diagnose a particular problem.
NOTE: When action=report, Bochs may spit out thousands of
debug messages per second, which can impact performance and fill
up your disk.
Give the path of the log file you’d like Bochs to log debugger
output. If you really don’t want it, make it ’/dev/null’, or
log: /dev/null (unix only)
sb16: This defines the SB16 sound emulation. It can have several of
the following properties. All properties are in this format:
PROPERTIES FOR sb16:
The filename is where the midi data is sent. This can be a
device or just a file if you want to record the midi data.
0 = No data should be output.
1 = output to device (system dependent - midi
denotes the device driver).
2 = SMF file output, including headers.
3 = Output the midi data stream to the file
(no midi headers and no delta times, just
command and data bytes).
This is the device/file where wave output is stored.
0 = no data
1 = output to device (system dependent - wave
denotes the device driver).
2 = VOC file output, including headers.
3 = Output the raw wave stream to the file.
The file to write the sb16 emulator messages to.
0 = No log.
1 = Resource changes, midi program and bank changes.
2 = Severe errors.
3 = All errors.
4 = All errors plus all port accesses.
5 = All errors and port accesses plus a lot
of extra information.
It is possible to change the loglevel at runtime.
Microseconds per second for a DMA cycle. Make it smaller to fix
non-continuous sound. 750000 is usually a good value. This
needs a reasonably correct setting for the IPS parameter
of the CPU option. It is possible to adjust the dmatimer at
sb16: midimode=1, midi=/dev/midi00,
wavemode=1, wave=/dev/dsp, loglevel=2,
NOTE: The example is wrapped onto three lines for formatting
reasons, but it should all be on one line in the actual
Video memory is scanned for updates and screen updated every so
many virtual seconds. The default value is 40000, about 25Hz.
Keep in mind that you must tweak the ’cpu: ips=N’ directive to
be as close to the number of emulated instructions-per-second
your workstation can do, for this to be accurate.
Approximate time in microseconds that it takes one character
to be transfered from the keyboard to controller over the
Approximate time in microseconds between attempts to paste
characters to the keyboard controller. This leaves time for the
guest os to deal with the flow of characters. The ideal setting
depends on how your operating system processes characters. The
default of 100000 usec (.1 seconds) was chosen because it works
consistently in Windows.
If your OS is losing characters during a paste, increase the
paste delay until it stops losing characters.
clock: This defines the parameters of the clock inside Bochs.
TO BE COMPLETED (see Greg explanation in feature request
Specifies the start (boot) time of the virtual machine. Use a
time value as returned by the time(2) system call. If no time0
value is set or if time0 equal to 1 (special case) or if time0
equal ’local’, the simulation will be started at the current
local host time. If time0 equal to 2 (special case) or if time0
equal ’utc’, the simulation will be started at the current utc
Default value are sync=none, time0=local
clock: sync=realtime, time0=938581955 # Wed Sep 29 07:12:35
mouse: This option prevents Bochs from creating mouse "events" unless a
mouse is enabled. The hardware emulation itself is not disabled
by this. You can turn the mouse on by setting enabled to 1, or
turn it off by setting enabled to 0. Unless you have a
particular reason for enabling the mouse by default, it is
recommended that you leave it off. You can also toggle the mouse
usage at runtime (control key + middle mouse button). With the
mouse type option you can select the type of mouse to emulate.
The default value is ’ps2’. The other choices are ’imps2’ (wheel
mouse on PS/2), ’serial’, ’serial_wheel’ (one com port requires
setting ’mode=mouse’) and ’usb’ (3-button mouse - one of the USB
ports must be connected with the ’mouse’ device - requires PCI
and USB support).
mouse: enabled=1, type=imps2
Requests that the GUI create and use it’s own non-shared
colormap. This colormap will be used when in the bochs
window. If not enabled, a shared colormap scheme may be used.
Once again, enabled=1 turns on this feature and 0 turns it
This option controls the presence of the i440FX PCI chipset. You
can also specify the devices connected to PCI slots. Up to 5
slots are available now. These devices are currently supported:
ne2k, pcivga, pcidev and pcipnic. If Bochs is compiled with
Cirrus SVGA support you’ll have the additional choice ’cirrus’.
i440fxsupport: enabled=1, slot1=pcivga, slot2=ne2k
Enables the mapping of a host PCI hardware device within the PCI
subsystem of the Bochs x86 emulator. This feature requires Linux
as a host OS.
pcidev: vendor=0x1234, device=0x5678
The vendor and device arguments should contain the vendor ID
respectively the device ID of the PCI device you want to map
within Bochs. The PCI mapping is still very experimental.
ne2k: Defines the characteristics of an attached ne2000 isa card :
PROPERTIES FOR ne2k:
ioaddr, irq: You probably won’t need to change ioaddr and irq,
unless there are IRQ conflicts. These parameters are ignored if
the NE2000 is assigned to a PCI slot.
mac: The MAC address MUST NOT match the address of any machine
on the net. Also, the first byte must be an even number (bit 0
set means a multicast address), and you cannot use
ff:ff:ff:ff:ff:ff because that’s the broadcast address. For the
ethertap module, you must use fe:fd:00:00:00:01. There may be
other restrictions too. To be safe, just use the b0:c4...
ethmod: The ethmod value defines which low level OS specific
module to be used to access physical ethernet interface. Current
implemented values include
- fbsd : ethernet on freebsd and openbsd
- linux : ethernet on linux
- win32 : ethernet on win32
- tap : ethernet through a linux tap interface
- tuntap : ethernet through a linux tuntap interface
If you don’t want to make connections to any physical networks,
you can use the following ’ethmod’s to simulate a virtual
- null : All packets are discarded, but logged to a few files
- arpback: ARP is simulated (disabled by default)
- vde : Virtual Distributed Ethernet
- vnet : ARP, ICMP-echo(ping), DHCP and TFTP are simulated
The virtual host uses 192.168.10.1
DHCP assigns 192.168.10.2 to the guest
The TFTP server use ethdev for the root directory
ethdev: The ethdev value is the name of the network interface on
your host platform. On UNIX machines, you can get the name by
running ifconfig. On Windows machines, you must run niclist to
get the name of the ethdev. Niclist source code is in
misc/niclist.c and it is included in Windows binary releases.
script: The script value is optional, and is the name of a
script that is executed after bochs initialize the network
interface. You can use this script to configure this network
interface, or enable masquerading. This is mainly useful for
the tun/tap devices that only exist during Bochs execution. The
network interface name is supplied to the script as first
ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:00, ethmod=fbsd,
ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:00,
ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:01,
ne2k: ioaddr=0x300, irq=9, mac=fe:fd:00:00:00:01, ethmod=tap,
ne2k: ioaddr=0x300, irq=9, mac=fe:fd:00:00:00:01,
ethmod=tuntap, ethdev=/dev/net/tun0, script=./tunconfig
ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:01, ethmod=vde,
ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:01, ethmod=vnet,
This enables a remap of a physical localized keyboard to a
virtualized us keyboard, as the PC architecture expects. If
enabled, the keymap file must be specified.
keyboard_mapping: enabled=1, map=gui/keymaps/x11-pc-de.map
Type of emulated keyboard sent back to the OS to a "keyboard
identify" command. It must be one of "xt", "at" or "mf".
This defines the keyboard shortcut to be sent when you press the
"user" button in the header bar. The shortcut string is a
combination of maximum 3 key names (listed below) separated with
a ’-’ character.
Valid key names:
"alt", "bksl", "bksp", "ctrl", "del", "down", "end", "enter",
"esc", "f1", ... "f12", "home", "ins", "left", "menu", "minus",
"pgdwn", "pgup", "plus", "right", "shift", "space", "tab", "up",
"win", "print" and "power".
This defines image file that can be loaded into the CMOS RAM at
startup. The rtc_init parameter controls whether initialize the
RTC with values stored in the image. By default the time0
argument given to the clock option is used. With
’rtc_init=image’ the image is the source for the initial time.
cmosimage: file=cmos.img, rtc_init=time0
usb1: This option controls the presence of the USB root hub which is a
part of the i440FX PCI chipset. With the portX option you can
connect devices to the hub (currently supported: ’mouse’ and
’keypad’). If you connect the mouse to one of the ports and use
the mouse option ’type=usb’ you’ll have a 3-button USB mouse.
usb1: enabled=1, port1=mouse, port2=keypad
This program is distributed under the terms of the GNU Lesser
General Public License as published by the Free Software
Foundation. See the COPYING file located in
/usr/local/share/doc/bochs/ for details on the license and the lack of
The latest version of this program can be found at:
bochs(1), bochs-dlx(1), bximage(1), bxcommit(1)
The Bochs IA-32 Emulator site on the World Wide Web:
Online Bochs Documentation
The Bochs emulator was created by Kevin Lawton
(firstname.lastname@example.org), and is currently maintained by the
members of the Bochs x86 Emulator Project. You can see a current
roster of members at:
Please report all bugs to the bug tracker on our web site. Just go
to http://bochs.sourceforge.net, and click "Bug Reports" on the sidebar
Provide a detailed description of the bug, the version of the program
you are running, the operating system you are running the program on
and the operating system you are running in the emulator.