Bochs User Manual
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# bochsrc

Bochs uses a configuration file called `bochsrc` to know where to look for disk images, how the Bochs emulation layer should work, etc. When you first start up Bochs, it looks around for its configuration file (see the Section called Search order for the configuration file in the Chapter called Using Bochs), and parses it. Here are a few lines from a sample file:

      ata0-master: type=disk, path="30M.sample", cylinders=615, heads=6, spt=17
      boot: disk

The format is very strict, so be sure to put the right number of spaces and use lowercase letters. As you can see, most lines have a keyword telling what is being configured, followed by a colon, followed by a few `variable`=`value` pairs, separated by commas. For very simple options, sometimes just a single value is needed. The source and binary distributions come with a sample `bochsrc`, so you can just copy the sample file and edit the settings you need to change.

The syntax used for `bochsrc` can also be used as command line arguments for Bochs. If you have any spaces in your command line arguments, they should be enclosed in single quotes, for example:

      bochs 'boot:floppy' 'floppya: 1_44=a.img, status=inserted'

For other arguments, see section Command line arguments.

Starting with version 1.3, you can use environment variables in the `bochsrc` file, for example:

      floppya: 1_44="$IMAGES/bootdisk.img", status=inserted
      boot: floppy

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. On Win32 and MacOSX, the default for the share directory is determined by a platform-specific specific algorithm. On Win32, we use the registry to see what directory Bochs and its support files were installed in. On MacOSX, the share directory is the directory where the application is located.

Starting with version 2.0, you can can use #include in the bochsrc to read the configuration from other files. Now it is possible to put platform or installation defaults in a global config file (e.g. location of rom images). Put this on top of your config file if the global configuration is stored in /etc:

     #include /etc/bochsrc

The section below lists all the supported `bochsrc` options.

## megs

Examples:

      megs: 32
      megs: 128

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.

| Due to limitations in the host OS, Bochs fails to allocated even 1024MB on most systems.

## cpu

Example:

      cpu: count=2, ips=10000000

This defines the parameters of the cpu inside Bochs:

count

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. For more information on SMP see the Section called Simulating a Symmetric Multiprocessor (SMP) Machine in the Chapter called Tips and Techniques.

quantum

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-on-triple-fault

Reset the CPU when triple fault occur (highly recommended) rather than PANIC. Remember that if you are trying to continue after triple fault the simulation will be completely bogus !

ips

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 in the status bar (if supported by the gui).

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 other benchmarks. The table below lists some typical IPS settings for different machines[1].

Table 1. Example IPS Settings

Bochs | Speed | Machine/Compiler | Typical IPS
--- | --- | --- | ---
2.2.6 | 2.6Ghz | Intel Core 2 Duo with WinXP/g++ 3.4 | 21 to 25 million
2.2.6 | 2.1Ghz | Athlon XP with Linux 2.6/g++ 3.4 | 12 to 15 million
2.0.1 | 1.6Ghz | Intel P4 with Win2000/g++ 3.3 | 5 to 7 million
1.4 | 650MHz | Athlon K-7 with Linux 2.4.x | 2 to 2.5 million
1.4 | 400MHz | Pentium II with Linux 2.0.x | 1 to 1.8 million

## romimage

Examples:

      romimage: file=bios/BIOS-bochs-latest, address=0xe0000
      romimage: file=$BXSHARE/BIOS-bochs-legacy, address=0xf0000
      romimage: file=mybios.bin, address=0xfff80000
      romimage: file=mybios.bin

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 now optional, since it can be calculated from image size.

## optromimage1, optromimage2, optromimage3 or optromimage4

Example:

       optromimage1: file=optionalrom.bin, address=0xd0000

This enables Bochs to 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

## vgaromimage

Examples:

      vgaromimage: file=bios/VGABIOS-elpin-2.40
      vgaromimage: file=$BXSHARE/VGABIOS-lgpl-latest
      vgaromimage: file=$BXSHARE/VGABIOS-lgpl-latest-cirrus

This tells Bochs what VGA ROM BIOS to load (at 0xC0000).

A VGA BIOS from Elpin Systems, Inc. as well as a free LGPL'd VGA BIOS are provided in the source and binary distributions.

| Please check with the vga option to decide what VGA BIOS to use.

## vga

Examples:

      vga: extension=cirrus
      vga: extension=vbe

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 (needs `VGABIOS-lgpl-latest` as VGA BIOS, see vgaromimage option) and 'cirrus' for Cirrus SVGA support (needs `VGABIOS-lgpl-latest-cirrus` as VGA BIOS).

## floppya/floppyb

Examples:

    2.88M 3.5" Floppy:
      floppya: 2_88=a:, status=inserted
    1.44M 3.5" Floppy:
      floppya: 1_44=floppya.img, status=inserted
    1.2M  5.25" Floppy:
      floppyb: 1_2=/dev/fd0, status=inserted
    720K  3.5" Floppy:
      floppya: 720k=/usr/local/bochs/images/win95.img, status=inserted
    auto-detect:
      floppya: image=floppy.img, status=inserted

Floppya is the first drive, and floppyb is the second drive. If you're booting from a floppy, floppya should point to a bootable disk. To read from a disk image, write the name of the image file. In many operating systems Bochs can read directly from a raw floppy drive. For raw disk access, use the device name (Unix systems) or the drive letter and a colon (Windows systems).

Following floppy disk types are supported: 2_88, 1_44, 1_2, 720k, 360k, 320k, 180k, 160k, as well as "image" to let Bochs auto-detect the type of floppy disk (does only work with images, not with raw floppy drives).

You can set the initial status of the media to `ejected` or `inserted`. Usually you will want to use `inserted`. In fact Bryce can't think of any reason to ever write `ejected` in your `bochsrc`.

## ata0, ata1, ata2, ata3

Examples:

    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

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 areenabled by default, with the values shown above.

## ata0-master, ata0-slave, ata1-*, ata2-*, ata3-*

Examples:

    ata0-master: type=disk, path=10M.img, mode=flat, cylinders=306, heads=4, spt=17, translation=none
    ata1-master: type=disk, path=2GB.cow, mode=vmware3, cylinders=5242, heads=16, spt=50, translation=echs
    ata1-slave:  type=disk, path=3GB.img, mode=sparse, cylinders=6541, heads=16, spt=63, translation=auto
    ata2-master: type=disk, path=7GB.img, mode=undoable, cylinders=14563, heads=16, spt=63, translation=lba
    ata2-slave:  type=cdrom, path=iso.sample, status=inserted

This defines the type and characteristics of all attached ata devices:

Table 2. ata devices configuration options

Option | Comments | Possible values
--- | --- | ---
type | type of attached device | [disk | cdrom]
path | path of the image |
mode | image type, only valid for disks | [flat | concat | external | dll | sparse | vmware3 | vmware4 | undoable | growing | volatile ]
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 done by the BIOS (legacy int13), only for disks | [none | lba | large | rechs | auto]
model | string returned by identify device ATA command |

You have to tell the type of the attached device. For Bochs 2.0 or later, it can be `disk` or `cdrom`.

You have to point the "path" at a hard disk image file, cdrom iso file, or physical cdrom device. To create a hard disk image, try running bximage (see the Section called How to make a simple disk image in the Chapter called Tips and Techniques). 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 for safety reasons. In Windows, there is no easy way.

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 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 sectors)

- large : a standard bitshift algorithm, for disks up to 4.2GB (8257536 sectors)

- 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)

Please see the Section called Disk translation in the Chapter called Tips and Techniques for a discussion on translation scheme.

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 : vmware version 3 disk support

- vmware4 : vmware version 4 disk support

- undoable : flat file with commitable redolog

- growing : growing file

- volatile : flat file with volatile redolog

Please see the Section called Disk Image Modes in the Chapter called Tips and Techniques for a discussion on disk modes.

Default values are:

       mode=flat, biosdetect=auto, translation=auto, model="Generic 1234"

The `biosdetect` option has currently no effect on the BIOS.

| Make sure the proper ata option is enabled when using a device on that ata channel.

## boot

Examples:

      boot: floppy
      boot: cdrom, disk
      boot: network, disk
      boot: cdrom, floppy, disk

This defines the boot sequence. 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.

## floppy_bootsig_check

Example:

      floppy_bootsig_check: disabled=1

This disables the 0xaa55 signature check on boot floppies The check is enabled by default.

## config_interface

The configuration interface is a series of menus or dialog boxes that allows you to edit all the settings that control Bochs' 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 available while the graphical version is only available when Bochs is compiled with wxWidgets support, see the Section called Compiling with the wxWidgets interface in the Chapter called Installation. If you do not use a config_interface line, Bochs will choose a default for you (usually textconfig).

| wxWidgets provides both a configuration interface and a display library. So if you use the "wx" configuration interface, you must also use the "wx" display library, see display_library option.

Examples:

      config_interface: textconfig
      config_interface: 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 option lets you choose which one you want to run with. If you do not use a display_library line, Bochs will choose a default for you.

| wxWidgets provides both a configuration interface and a display library. So if you use the "wx" display library, you must also use the "wx" configuration interface, see config_interface option.

Examples:

      display_library: x
      display_library: sdl

Starting with version 2.2, some display libraries support specific options:

      display_library: rfb, options="timeout=60"  # time to wait for client
      display_library: sdl, options="fullscreen"  # startup in fullscreen mode
      display_library: win32, options="legacyF12" # use F12 to toggle mouse
      display_library: win32, options="windebug" # use experimental debugger gui

Table 3. display_library values

Option | Description
--- | ---
x | use X windows interface, cross platform
win32 | use native win32 libraries
carbon | use Carbon library (for MacOS X)
beos | use native BeOS libraries
macintosh | use MacOS pre-10
amigaos | use native AmigaOS libraries
sdl | use SDL library, cross platform, details in the Section called Compiling with the SDL interface in the Chapter called Installation
svga | use SVGALIB library for Linux, allows graphics without X windows
term | text only, uses curses/ncurses library, cross platform
rfb | provides an interface to AT&T's VNC viewer, cross platform, details in the Section called Compiling with the RFB interface in the Chapter called Installation
wx | use wxWidgets library, cross platform, details in the Section called Compiling with the wxWidgets interface in the Chapter called Installation
nogui | no display at all

## log

Examples:

      log: bochsout.txt
      log: -
      log: /dev/tty               (Unix only)
      log: /dev/null              (Unix only)
      log: nul                    (win32 only)

Give the path of the log file you'd like Bochs debug and misc. verbiage to be to be written to. If you don't use this option or set the filename to '-' the output is written to the console. If you really don't want it, make it "/dev/null" (Unix) or "nul" (win32). :^(

## logprefix

Examples:

       logprefix: %t-%e-@%i-%d
       logprefix: %i%e%d

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 current cpu eip (ignored in SMP configuration)
      %e : 1 character event type ('i'nfo, 'd'ebug, 'p'anic, 'e'rror)
      %d : 5 characters string of the device, between brackets

Default is %t%e%d

## debug/info/error/panic

Examples:

      debug: action=ignore
      info: action=report
      error: action=report
      panic: action=ask

During simulation, Bochs encounters certain events that the user might want to know about. These events are divided into four levels of importance: debug, info, error, and panic. Debug messages are usually only useful when writing Bochs code or when trying to locate a problem. There may be thousands of debug messages per second, so be careful before turning them on. Info messages tell about interesting events that don't happen that frequently. 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. Panic messages mean that Bochs cannot simulate correctly and should probably shut down. A panic can be a configuration problem (like a misspelled bochsrc line) or an emulation problem (like an unsupported video mode).

The debug, info, error, and panic lines in the bochsrc control what Bochs will do when it encounters each type of event. The allowed actions are: fatal (terminate bochs), ask (ask the user what to do), report (print information to the console or log file), or ignore (do nothing). The recommended settings are listed in the sample above.

| The safest action for panics is "fatal" or "ask". If you are getting lots of panics and get tired of telling it to continue each time, 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 after a panic occurs. Please report panic messages to the bochs-developers mailing list unless it is just a configuration problem like "could not find hard drive image."

## debugger_log

Examples:

      debugger_log: debugger.out
      debugger_log: /dev/null              (Unix only)
      debugger_log: -

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 '-'.

## com[1-4]

Examples:

      com1: enabled=1, mode=null
      com1: enabled=1, mode=mouse
      com1: enabled=1, mode=term, dev=/dev/ttyp9
      com2: enabled=1, mode=file, dev=serial.out
      com3: enabled=1, mode=raw, dev=com1
      com3: enabled=1, mode=socket, dev=localhost:8888

This defines a serial port (UART type 16550A).

When using the mode '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 of 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), 'mouse' (standard serial mouse - requires mouse option setting 'type=serial' or 'type=serial_wheel') and 'socket' (connect a networking socket).

## parport[1-2]

Examples:

      parport1: enabled=1, file="parport.out"
      parport2: enabled=1, file="/dev/lp0"
      parport1: enabled=0

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, "lpt1" on win32 platforms).

## sb16

Example:

      sb16: midimode=1, midi=/dev/midi00, wavemode=1, wave=/dev/dsp,
            loglevel=2, log=sb16.log, dmatimer=600000

| The example is wrapped onto several lines for formatting reasons, but it should all be on one line in the actual `bochsrc` file.

This defines the Sound Blaster 16 emulation, see the Section called Sound Blaster 16 Emulation for more information. It can have several of the following properties. All properties are in the usual "property=value" format.

- midi: The filename is where the midi data is sent to. This can be a device or just a file if you want to record the midi data. On a Windows host this parameter is ignored when using output to the sound device.

- midimode:

         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).

- wave: This is the device/file where wave output is stored. On a Windows host this parameter is ignored when using output to the sound device.

- wavemode:

         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.

- log: The file to write the sb16 emulator messages to.

- loglevel:

         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.

- dmatimer: 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 paramter of the cpu option. It is possible to adjust the dmatimer value at runtime.

## vga_update_interval

Examples:

      vga_update_interval: 40000 # default
      vga_update_interval: 250000

Video memory is scanned for updates and screen updated every so many virtual microseconds. Keep in mind that you must tweak the ips parameter of the cpu option to be as close to the number of emulated instructions-per-second your workstation can do, for this to be accurate.

## keyboard_serial_delay

Example:

      keyboard_serial_delay: 250 # default

Approximate time in microseconds that it takes one character to be transfered from the keyboard to controller over the serial path.

## keyboard_paste_delay

Example:

      keyboard_paste_delay: 100000 # default

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.

## ips

Examples:

      ips: 2000000 # default
      ips: 10000000

Emulated Instructions Per Second. This option is deprecated. Use the ips parameter of the cpu option instead.

## clock

This defines the parameters of the clock inside Bochs:

sync

TO BE COMPLETED (see Greg's explanation in feature request #536329)

time0

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 time.

    Syntax:
      clock: sync=[none|slowdown|realtime|both], time0=[timeValue|local|utc]

    Examples:
      clock: sync=none,     time0=local       # Now (localtime)
      clock: sync=slowdown, time0=315529200   # Tue Jan  1 00:00:00 1980
      clock: sync=none,     time0=631148400   # Mon Jan  1 00:00:00 1990
      clock: sync=realtime, time0=938581955   # Wed Sep 29 07:12:35 1999
      clock: sync=realtime, time0=946681200   # Sat Jan  1 00:00:00 2000
      clock: sync=none,     time0=1           # Now (localtime)
      clock: sync=none,     time0=utc         # Now (utc/gmt)

    Default value are sync=none, time0=local

## mouse

Examples:

      mouse: enabled=1
      mouse: enabled=1, type=imps2
      mouse: enabled=1, type=serial
      mouse: enabled=0

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 (see headerbar).

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' and 'serial_msys' (one com port requires setting 'mode=mouse', see com option). To connect a mouse to an USB port, see the usb1 option (requires PCI and USB support).

## private_colormap

Example:

      private_colormap: enabled=1

Requests that the GUI creates and uses its 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 off.

## i440fxsupport

Examples:

      i440fxsupport: enabled=1 # default if compiled with PCI support
      i440fxsupport: enabled=1, slot1=pcivga, slot2=ne2k

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. 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'.

## pcidev

Example:

      pcidev: vendor=0xbabe, device=0x2bad

Enables the mapping of a host PCI hardware device within the virtual PCI subsystem of the Bochs x86 emulator. The arguments `vendor` and `device` should contain the PCI vendor ID respectively the PCI device ID of the host PCI device you want to map within Bochs.

| The PCI device mapping is still in a very early stage of development and thus it is very experimental. This feature requires Linux as a host operating system.

Besides the `pcidev` config line you will need to load a pcidev kernel module within your Linux host OS. This kernel module is located in the `bochs/host/linux/pcidev/` directory.

## usb1

Examples:

      usb1: enabled=1, port1=mouse, port2=keypad
      usb1: enabled=1, port1=tablet, port2=disk:usbdisk.img

This option controls the presence of the USB root hub which is a part of the i440FX PCI chipset.

With the port`X` option you can connect devices to the hub (currently supported: 'mouse', 'tablet', 'keypad' and 'disk'). If you connect the mouse or tablet to one of the ports, Bochs forwards the mouse movement data to the USB device instead of the selected mouse type. When connecting the keypad to one of the ports, Bochs forwards the input of the numeric keypad to the USB device instead of the PS/2 keyboard. To connect a flat image as an USB hardisk you can use the 'disk' device with the path to the image separated with a colon (see above).

| PCI support must be enabled.

## gdbstub

Example:

      gdbstub: enabled=1, port=1234, text_base=0, data_base=0, bss_base=0

Default:

      gdbstub: enabled=0

This enables the GDB stub. See the Section called Using Bochs and the remote GDB stub in the Chapter called Tips and Techniques.

## ne2k

The ne2k line configures an emulated NE2000-compatible Ethernet adapter, which allows the guest machine to communicate on the network. To disable the NE2000 just comment out the ne2k line.

Examples:

    ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:00, ethmod=fbsd, ethdev=xl0
    ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:00, ethmod=fbsd, ethdev=en0 #macosx
    ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:00, ethmod=linux, ethdev=eth0
    ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:01, ethmod=win32, ethdev=MYCARD
    ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:01, ethmod=vde, ethdev="/tmp/vde.ctl"
    ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:01, ethmod=vnet, ethdev="c:/temp"
    ne2k: ioaddr=0x300, irq=9, mac=fe:fd:00:00:00:01, ethmod=tap, ethdev=tap0
    ne2k: ioaddr=0x300, irq=9, mac=fe:fd:00:00:00:01, ethmod=tuntap, ethdev=/dev/net/tun0, script=./tunconfig

    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... address.

    ethmod: The ethmod value defines which low level OS specific module to be
    used to access physical ethernet interface. You can also specify a network
    simulator or a module with no input/output ("null"). See the table below for
    currently supported values.

    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 parameter

The following table shows the available ethernet modules with description, whether the "ethdev" and "script" parameters are used or not and the Bochs version where this module was added.

Table 4. Ethernet modules

Module | Description | ethdev | script | Bochs version
--- | --- | --- | --- | ---
arpback | ARP simulator - disabled by default. | No | No | 1.3
fbsd | FreeBSD / OpenBSD packetmover. | Yes | No | 1.0
linux | Linux packetmover - 'root' privileges required, no connection to the host machine. | Yes | No | 1.3
null | Null packetmover. All packets are discarded, but logged to a few files. | No | No | 1.0
tap | TAP packetmover. | Yes | Yes | 1.4
tuntap | TUN/TAP packetmover - see Configuring and using a tuntap network interface. | Yes | Yes | 2.0
vde | Virtual Distributed Ethernet packetmover. | Yes | Yes | 2.2
vnet | ARP, ping (ICMP-echo), DHCP and read/write TFTP simulation. The virtual host uses 192.168.10.1. DHCP assigns 192.168.10.2 to the guest. The TFTP server uses the ethdev value for the root directory and doesn't overwrite files. | Yes, for TFTP | No | 2.2
win32 | Win32 packetmover - WinPCap driver required. | Yes | No | 1.3

## keyboard_mapping

Examples:

      keyboard_mapping: enabled=0, map=
      keyboard_mapping: enabled=1, map=gui/keymaps/x11-pc-de.map

This enables a remap of a physical localized keyboard to a virtualized U.S. keyboard, as the PC architecture expects. If enabled, the keymap file must be specified. Keyboard mapping is available for X windows, SDL (Linux port) and wxWidgets (GTK port). For SDL you have to use keymaps designed for SDL, the wxWidgets GUI uses the keymaps for X windows.

## keyboard_type

Examples:

      keyboard_type: xt
      keyboard_type: at
      keyboard_type: mf

Type of keyboard returned by a "identify keyboard" command to the keyboard controller. It must be one of "xt", "at" or "mf". Defaults to "mf". It should be ok for almost everybody. A known exception is French macs, that do have a "at"-like keyboard.

## user_shortcut

Examples:

      user_shortcut: keys=ctrl-alt-del
      user_shortcut: keys=ctrl-alt-esc

This defines the keyboard shortcut to be sent when you press the "user" button in the headerbar. The shortcut string is a combination of maximum 3 key names (listed below) separated with a '-' character. The old-style syntax (without the '-') still works for the key combinations supported in Bochs 2.2.1.

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" and "print".

## cmosimage

Example:

      cmosimage: file=cmos.img, rtc_init=time0

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.

## magic_break

Example:

      magic_break: enabled=1

This enables the "magic breakpoint" feature when using the debugger. The useless cpu instruction XCHG BX, BX causes Bochs to enter the debugger mode. This might be useful for software development.

### Notes

[1] | IPS measurements depend on OS and compiler configuration in addition to processor clock speed.

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