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 directory.
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/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).
Controls the presence of optional device plugins. These plugins are loaded directly with this option and some of them install a config option that is only available when the plugin device is loaded. The value "1" means to load the plugin and "0" will unload it (if loaded before).
These plugins will be loaded by default (if present): 'biosdev', 'extfpuirq', 'gameport', 'iodebug','parallel', 'serial', 'speaker' and 'unmapped'.
These plugins are also supported, but they are usually loaded directly with their bochsrc option: 'e1000', 'es1370', 'ne2k', 'pcidev', 'pcipnic', 'sb16', 'usb_ehci', 'usb_ohci', 'usb_uhci', 'usb_xhci' and 'voodoo'.
plugin_ctrl: unmapped=0, e1000=1 # unload 'unmapped' and load 'e1000'
The configuration interface is a series of menus or dialog boxes that allows you to change all the settings that control Bochs's behavior. Depending on the platform there are up to 3 choices of configuration interface: a text mode version called "textconfig" and two graphical versions called "win32config" and "wx". The text mode version uses stdin/stdout or gui console (if available / runtime config) and is always compiled in, unless Bochs is compiled for wx only. The choice "win32config" is only available on win32/win64 and it is the default on these platforms. The choice "wx" is only available when Bochs is compiled with wxWidgets support. If you do not write a config_interface line, Bochs will choose a default for you.
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 for you.
The choices are:
x X windows interface, cross platform
win32 native win32 libraries
carbon Carbon library (for MacOS X)
macintosh MacOS pre-10
amigaos native AmigaOS libraries
sdl SDL 1.2.x library, cross platform
sdl2 SDL 2.x library, cross platform
term text only, uses curses/ncurses library, cross platform
rfb provides an interface to AT&T's VNC viewer, cross platform
vncsrv use LibVNCServer for extended RFB(VNC) support
wx wxWidgets library, cross platform
nogui no display at all
NOTE: If you use the "wx" configuration interface, you must also use the "wx" display library.
Specific options: Some display libraries now support specific options to control their behaviour. These options are supported by more than one display library:
"cmdmode" - call a headerbar button handler after pressing F7 (x, sdl, sdl2)
"fullscreen" - startup in fullscreen mode (sdl, sdl2)
"gui_debug" - use GTK debugger gui (sdl, sdl2, x)
"hideIPS" - disable IPS output in status bar (rfb, sdl, sdl2, term, vncsrv, wx, x)
"nokeyrepeat" - turn off host keyboard repeat (sdl, sdl2, x)
"no_gui_console" - use system console instead of builtin gui console (rfb, sdl, sdl2, vncsrv, x)
"timeout" - time (in seconds) to wait for client (rfb, vncsrv)
NOTE: Setting up options without specifying display library is also supported.
display_library: sdl2, options=fullscreen,hideIPS
This defines cpu-related parameters inside Bochs:
Selects CPU configuration to emulate from pre-defined list of all supported configurations. When this option is used and the value is different from 'bx_generic', the parameters of the CPUID option have no effect anymore. See the bochsrc sample for supported values.
Set the number of processors:cores per processor:threads per core when Bochs is compiled for SMP emulation. Bochs currently supports up to 14 threads (legacy APIC) or 254 threads (xAPIC or higher) running simultaniosly. 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 !
Determine whether to limit maximum CPUID function to 2. This mode is required to workaround WinNT installation and boot issues.
When this option is enabled MWAIT will not put the CPU into a sleep state. This option exists only if Bochs compiled with --enable-monitor-mwait.
Define path to user CPU Model Specific Registers (MSRs) specification. See example in msrs.def.
Ignore MSR references that Bochs does not understand; print a warning message instead of generating #GP exception. This option is enabled by default but will not be available if configurable MSRs are enabled.
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 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.
Bochs Machine/Compiler Mips 2.4.6 3.4Ghz Core i7 2600 w/ Win7x64/g++ 4.5.2 85-95 Mips 2.3.7 3.2Ghz Core 2 Q9770 w/ WinXP/g++ 3.4 50-55 Mips 2.3.7 2.6Ghz Core 2 Duo w/ WinXP/g++ 3.4 38-43 Mips 2.2.6 2.6Ghz Core 2 Duo w/ WinXP/g++ 3.4 21-25 Mips 2.2.6 2.1Ghz Athlon XP w/ Linux 2.6/g++ 3.4 12-15 Mips
 IPS measurements depend on OS and compiler configuration in addition to processor clock speed.
cpu: count=2, ips=10000000, msrs="msrs.def"
This defines features and functionality supported by Bochs emulated CPU:
Set emulated CPU level information returned by CPUID. Default value is determined by configure option --enable-cpu-level. Currently supported values are 5 (for Pentium and similar processors) and 6 (for P6 and later processors).
Set family information returned by CPUID. Default family value determined by configure option --enable-cpu-level.
Set model information returned by CPUID. Default model value is 3.
Set stepping information returned by CPUID. Default stepping value is 3.
Set the CPUID vendor string returned by CPUID(0x0). This should be a twelve-character ASCII string.
Set the CPUID vendor string returned by CPUID(0x80000002 .. 0x80000004). This should be at most a forty-eight-character ASCII string.
Select MMX instruction set support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 5.
Select APIC configuration (LEGACY/XAPIC/XAPIC_EXT/X2APIC). This option exists only if Bochs compiled with BX_CPU_LEVEL >= 5.
Select SYSENTER/SYSEXIT instruction set support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select SIMD instructions support. Any of NONE/SSE/SSE2/SSE3/SSSE3/SSE4_1/SSE4_2/AVX/AVX2/AVX512 could be selected.
This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6. The AVX choises exists only if Bochs compiled with --enable-avx option.
Select AMD SSE4A instructions support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select AMD Misaligned SSE mode support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select AES instruction set support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select SHA instruction set support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select MOVBE Intel(R) Atom instruction support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select ADCX/ADOX instructions support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select XSAVE extensions support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select XSAVEOPT instruction support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select AVX float16 convert instructions support. This option exists only if Bochs compiled with --enable-avx option.
Select AVX fused multiply add (FMA) instructions support. This option exists only if Bochs compiled with --enable-avx option.
Select BMI1/BMI2 instructions support. This option exists only if Bochs compiled with --enable-avx option.
Select AMD four operand FMA instructions support. This option exists only if Bochs compiled with --enable-avx option.
Select AMD XOP instructions support. This option exists only if Bochs compiled with --enable-avx option.
Select AMD TBM instructions support. This option exists only if Bochs compiled with --enable-avx option.
Enable x85-64 and long mode support. This option exists only if Bochs compiled with x86-64 support.
Enable 1G page size support in long mode. This option exists only if Bochs compiled with x86-64 support.
Enable Process-Context Identifiers (PCID) support in long mode. This option exists only if Bochs compiled with x86-64 support.
Enable Supervisor Mode Execution Protection (SMEP) support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Enable Supervisor Mode Access Prevention (SMAP) support. This option exists only if Bochs compiled with BX_CPU_LEVEL >= 6.
Select MONITOR/MWAIT instructions support. This option exists only if Bochs compiled with --enable-monitor-mwait.
Select VMX extensions emulation support. This option exists only if Bochs compiled with --enable-vmx option.
Select AMD SVM (Secure Virtual Machine) extensions emulation support. This option exists only if Bochs compiled with --enable-svm option.
cpuid: mmx=1, sep=1, sse=sse4_2, xapic=1, aes=1, movbe=1, xsave=1
Set the amount of physical memory you want to emulate.
Set amount of guest physical memory to emulate. The default is 32MB, the maximum amount limited only by physical address space limitations.
Set amount of host memory you want to allocate for guest RAM emulation. It is possible to allocate less memory than you want to emulate in guest system. This will fake guest to see the non-existing memory. Once guest system touches new memory block it will be dynamically taken from the memory pool. You will be warned (by FATAL PANIC) in case guest already used all allocated host memory and wants more.
memory: guest=512, host=256
The 'megs:' option sets the 'guest' and 'host' memory parameters to the same value. In all other cases the 'memory' option should be used instead.
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 0xfffe0000, and it is exactly 128k long. The legacy version of the Bochs BIOS is usually loaded starting at address 0xffff0000, and it is exactly 64k long. You can 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. The Bochs BIOS currently supports only the option "fastboot" to skip the boot menu delay.
romimage: file=bios/BIOS-bochs-latest, options=fastboot
romimage: file=mybios.bin, address=0xfff80000
You also need to load a VGA ROM BIOS into 0xC0000.
- 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
This defines parameters related to the VGA display.
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, 'cirrus' for Cirrus SVGA support and 'voodoo' for Voodoo Graphics support (see 'voodoo' option).
This parameter specifies the number of display updates per second. The VGA update timer by default uses the realtime engine with a value of 5. This parameter can be changed at runtime.
If set to 1 (default), the VGA timer is based on realtime, otherwise it is driven by the cpu and depends on the ips setting. If the host is slow (low ips, update_freq) and the guest uses HLT appropriately, setting this to 0 and "clock: sync=none" may improve the responsiveness of the guest GUI when the guest is otherwise idle.
This parameter defines the behaviour of the DDC emulation that returns the monitor EDID data. By default the 'builtin' values for 'Bochs Screen' are used. Other choices are 'disabled' (no DDC emulation) and 'file' (read monitor EDID from file / path name separated with a colon).
vga: extension=none, update_freq=10, realtime=0, ddc=disabled
vga: extension=cirrus, update_freq=30, ddc=file:monitor.bin
This defines the Voodoo Graphics emulation (experimental). Currently supported models are 'voodoo1', 'voodoo2', 'banshee' and 'voodoo3'. The Voodoo2 support is not yet complete, but almost usable. The Banshee / Voodoo3 support is under construction, but basically usable. The 2D/3D cards require an external VGA BIOS the vga extension option to be set to 'voodoo'. If the i440BX PCI chipset is selected, they can be assigned to AGP (slot #5). The gui screen update timing for all models is controlled by the related 'vga' options.
voodoo: enabled=1, model=voodoo1
This defines parameters related to the emulated keyboard:
Type of keyboard return 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.
Approximate time in microseconds that it takes one character to be transferred from the keyboard to controller over the serial path.
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.
This enables a remap of a physical localized keyboard to a virtualized us keyboard, as the PC architecture expects.
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", "power", "print", "right", "scrlck", "shift", "space", "tab", "up" and "win".
keyboard: type=mf, serial_delay=200, paste_delay=100000
This defines parameters for the emulated mouse type, the initial status of the mouse capture and the runtime method to toggle it.
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', 'serial_msys' (one com port requires setting 'mode=mouse') 'inport' and 'bus' (if present). To connect a mouse to a USB port, see the 'usb_uhci', 'usb_ohci', 'usb_ehci' or 'usb_xhci' option (requires PCI and USB support).
The Bochs gui creates mouse "events" unless the 'enabled' option is set to 0. The hardware emulation itself is not disabled by this. 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 (RFB, SDL, Win32, wxWidgets and X11 - see below).
The default method to toggle the mouse capture at runtime is to press the CTRL key and the middle mouse button ('ctrl+mbutton'). This option allows to change the method to 'ctrl+f10' (like DOSBox), 'ctrl+alt' (like QEMU) or 'f12'.
mouse: type=imps2, enabled=1
mouse: type=serial, enabled=1
mouse: enabled=0, toggle=ctrl+f10
This defines the parameters to set up the Bochs PCI emulation:
If Bochs is compiled with PCI support, it is enabled by default.
Currently the chipsets i430FX, i440FX and i440BX (limited) are supported and the default is i440FX.
It is possible to specify the devices connected to PCI slots. Up to 5 slots are available. For combined PCI/ISA devices assigning to slot is mandatory if the PCI model should be emulated (cirrus, ne2k and pcivga). Setting up slot for PCI-only devices is also supported, but they are auto-assigned if not specified (e1000, es1370, pcidev, pcipnic, usb_ehci, usb_ohci, usb_xhci, voodoo). All device models except the network devices ne2k and e1000 can be used only once in the slot configuration. In case of the i440BX chipset, the slot #5 is the AGP slot. Currently only the 'voodoo' device can be assigned to AGP.
With the advanced PCI options it is possible to control the behaviour of the PCI chipset. These options can be specified as comma-separated values. By default the "Bochs i440FX" chipset enables the ACPI and HPET devices, but original i440FX doesn't support them. The options 'noacpi' and 'nohpet' make it possible to disable them. The option 'noagp' disables the incomplete AGP subsystem of the i440BX chipset.
pci: enabled=1, chipset=i440fx, slot1=pcivga, slot2=ne2k, advopts=noacpi
This defines the parameters of the clock inside Bochs.
This defines the method how to synchronize the Bochs internal time with realtime. With the value 'none' the Bochs time relies on the IPS value and no host time synchronization is used. The 'slowdown' method sacrifices performance to preserve reproducibility while allowing host time correlation. The 'realtime' method sacrifices reproducibility to preserve performance and host-time correlation. It is possible to enable both synchronization methods.
If this option is enabled together with the realtime synchronization, the RTC runs at realtime speed. This feature is disabled by default.
Specifies the start (boot) time of the virtual machine. Use a time value as returned by the time(2) system call or a string as returned by the ctime(3) 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.
clock: sync=[none|slowdown|realtime|both], time0=[timeValue|local|utc]
Default value are sync=none, rtc_sync=0, time0=local
clock: sync=realtime, time0=938581955 # Wed Sep 29 07:12:35 1999
clock: sync=realtime, time0="Sat Jan 1 00:00:00 2000" # 946681200
This defines a binary image file with size 128 bytes 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
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 off.
- 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 bootable disk.
You can set the initial status of the media to 'ejected' or 'inserted'. Usually you will want to use 'inserted'.
The parameter 'type' can be used to enable the floppy drive without media and status specified. Usually the drive type is set up based on the media type.
The optional parameter 'write_protected' can be used to control the media write protect switch. By default it is turned off.
2.88M 3.5" media:
floppya: 2_88=path, status=ejected
1.44M 3.5" media (write protected):
floppya: 1_44=path, status=inserted, write_protected=1
1.2M 5.25" media:
floppyb: 1_2=path, status=ejected
720K 3.5" media:
floppya: 720k=path, status=inserted
360K 5.25" media:
floppya: 360k=path, status=inserted
Autodetect floppy media type:
floppya: image=path, status=inserted
Use directory as 1.44M VFAT media:
floppya: 1_44=vvfat:path, status=inserted
1.44M 3.5" floppy drive, no media:
- 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 devices:
type= type of attached device [disk|cdrom]
path= path of the image
mode= image mode [flat|concat|sparse|vmware3|vmware4|undoable|growing|volatile|vpc|vbox|vvfat], 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 [auto|cmos|none]
translation=type of translation of the bios, only for disks [none|lba|large|rechs|auto]
model= string returned by identify device command
journal= optional filename of the redolog for undoable, volatile and vvfat disks
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 mandatory for hard disks. 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. In all cases the disk size reported from the image must be exactly C*H*S*512.
The mode option defines how the disk image is handled. Disks can be defined as:
- flat : one file flat layout
- concat : multiple files layout
- sparse : stackable, commitable, rollbackable
- vmware3 : vmware3 disk support
- vmware4 : vmware4 disk support (aka VMDK)
- undoable : flat file with commitable redolog
- growing : growing file
- volatile : flat file with volatile redolog
- vpc : fixed / dynamic size VirtualPC image
- vbox : fixed / dynamic size Oracle(tm) VM VirtualBox image (VDI version 1.1)
- vvfat: local directory appears as read-only VFAT disk (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 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)
Default values are:
mode=flat, biosdetect=auto, translation=auto, model="Generic 1234"
The biosdetect option has currently no effect on the bios
ata0-master: type=disk, path=10M.sample, cylinders=306, heads=4, spt=17
ata0-slave: type=disk, path=20M.sample, cylinders=615, heads=4, spt=17
ata1-master: type=disk, path=30M.sample, cylinders=615, heads=6, spt=17
ata1-slave: type=disk, path=46M.sample, cylinders=940, heads=6, spt=17
ata2-master: type=disk, path=62M.sample, cylinders=940, heads=8, spt=17
ata2-slave: type=disk, path=112M.sample, cylinders=900, heads=15, spt=17
ata3-master: type=disk, path=483M.sample, cylinders=1024, heads=15, spt=63
ata3-slave: type=cdrom, path=iso.sample, status=inserted
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.
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 it /dev/null.
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, 'e'rror)
%d : 5 characters string of the device, between brackets
Default : %t%e%d
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), ask (ask user how to proceed) or report (print information to the log file).
The safest setting is action=fatal or action=ask. 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."
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), ask (ask user how to proceed), warn (show dialog with message and continue), report (print information to the log file), or ignore (do nothing).
This setting tells Bochs what to do when an event occurs that generates informational messages. You can set this to report (print information to the log file), or ignore (do nothing). For general usage, the "report" option is probably a good choice.
This setting tells Bochs what to do with messages intended to assist in debugging. You can set this to report (print information to the log file), 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)
- com1: , com2: , com3: or com4:
This defines a serial port (UART type 16550A). In the 'term' mode 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.
In socket* and pipe* (win32 only) modes Bochs becomes either socket/named pipe client or server. In client mode it connects to an already running server (if connection fails Bochs treats com port as not connected). In server mode it opens socket/named pipe and waits until a client application connects to it before starting simulation. This mode is useful for remote debugging (e.g. with gdb's "target remote host:port" command or windbg's command line option -k com:pipe,port=\.pipepipename). Socket modes use simple TCP communication, pipe modes use duplex byte mode pipes.
Other serial modes are 'null' (no input/output), 'file' (output to a file specified as the 'dev' parameter and changeable at runtime), 'raw' (use the real serial port - partly implemented on win32) and 'mouse' (standard serial mouse - requires mouse option setting 'type=serial', 'type=serial_wheel' or 'type=serial_msys')
com1: enabled=1, mode=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). The output file can be changed at runtime.
parport1: enabled=1, file=parport.out
parport2: enabled=1, file="/dev/lp0"
This defines the lowlevel sound driver(s) for the wave (PCM) input / output and the MIDI output feature and (if necessary) the devices to be used. It can have several of the following properties. All properties are in the format sound: property=value
This defines the driver to be used for the waveout feature.
Possible values are 'file' (all wave data sent to file), 'dummy' (no
output) and the platform-dependant drivers 'alsa', 'oss', 'osx', 'sdl'
This defines the device to be used for wave output (if necessary) or
the output file for the 'file' driver.
This defines the driver to be used for the wavein feature.
Possible values are 'dummy' (recording silence) and platform-dependent
drivers 'alsa', 'oss', 'sdl' and 'win'.
This defines the device to be used for wave input (if necessary).
This defines the driver to be used for the MIDI output feature.
Possible values are 'file' (all MIDI data sent to file), 'dummy' (no
output) and platform-dependent drivers 'alsa', 'oss', 'osx' and 'win'.
This defines the device to be used for MIDI output (if necessary).
This defines the driver to be used for all sound features with one
property. Possible values are 'default' (platform default) and all
other choices described above. Overriding one or more settings with
the specific driver parameter is possible.
Example for one driver (uses platform-default):
sound: driver=default, waveout=/dev/dsp Example for different drivers:
sound: waveoutdrv=sdl, waveindrv=alsa, midioutdrv=dummy
This defines the PC speaker output mode. In the 'sound' mode the beep is generated by the square wave generator which is a part of the lowlevel sound support. In this mode the 'volume' parameter can be used to set the output volume (0 - 15). The 'system' mode is only available on Linux and Windows. On Linux /dev/console is used for output and on Windows the Beep() function. The 'gui' mode forwards the beep to the related gui methods (currently only used by the Carbon gui).
speaker: enabled=1, mode=sound, volume=15
This defines the SB16 sound emulation. It can have several of the following properties. All properties are in this format:
PROPERTIES FOR sb16:
This optional property controls the presence of the SB16 emulation.
The emulation is turned on unless this property is used and set to 0.
This parameter specifies what to do with the MIDI output.
0 = no output
1 = output to device specified with the sound option (system dependent)
2 = MIDI or raw data output to file (depends on file name extension)
3 = dual output (mode 1 and 2 at the same time)
This is the file where the midi output is stored (midimode 2 or 3).
This parameter specifies what to do with the PCM output.
0 = no output
1 = output to device specified with the sound option (system dependent)
2 = VOC, WAV or raw data output to file (depends on file name extension)
3 = dual output (mode 1 and 2 at the same time)
This is the file where the wave output is stored (wavemode 2 or 3).
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 runtime.
Examples for output modes:
sb16: midimode=2, midifile="output.mid", wavemode=1 # MIDI to file
sb16: midimode=1, wavemode=3, wavefile="output.wav" # wave to file and device
This defines the ES1370 sound emulation (recording and playback - except DAC1+DAC2 output at the same time). The parameter 'enabled' controls the presence of the device. The wave and MIDI output can be sent to device, file or both using the parameters 'wavemode', 'wavefile', 'midimode' and 'midifile'. See the description of these parameters at the SB16 directive.
Example for using 'sound' parameters:
es1370: enabled=1, wavemode=1 Example for sending output to file:
es1370: enabled=1, wavemode=2, wavefile=output.voc
Defines the characteristics of an attached ne2000 isa card :
PROPERTIES FOR ne2k:
CARD: This is the zero-based card number to configure with this ne2k config line. Up to 4 devices are supported now (0...3). If not specified, the following parameters apply to card #0.
TYPE: This is the card type to emulate ('isa' or 'pci'). If not specified, card #0 defaults to 'pci' if assigned to a pci slot. For the additional cards the type parameter should be set up.
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. 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
- slirp : built-in Slirp support with DHCP / TFTP servers
If you don't want to make connections to any physical networks, you can use the following 'ethmod's to simulate a virtual network.
- null : All packets are discarded, but logged to a few files
- vde : Virtual Distributed Ethernet
- vnet : ARP, ICMP-echo(ping), DHCP, DNS, FTP and TFTP are simulated
The virtual host uses 192.168.10.1
DHCP assigns 192.168.10.15 to the guest
The FTP and TFTP servers use 'ethdev' for the root directory
TFTP doesn't overwrite files, DNS for server and client only
- socket : Connect up to 6 Bochs instances with external program 'bxhub'
(simulating an ethernet hub). It provides the same services as the
'vnet' module and assigns IP addresses like 'slirp' (10.0.2.x).
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. The 'socket' module uses this parameter to specify the UDP port for receiving packets and (optional) the host to connect.
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 'slirp' module uses this parameter to specify a config file for setting up an alternative IP configuration or additional features. The 'vnet' module also uses this parameter to specify a config file similar to slirp, but with only a few settings.
BOOTROM: The bootrom value is optional, and is the name of the ROM image to load. Note that this feature is only implemented for the PCI version of the NE2000.
ne2k: ioaddr=0x300, irq=9, mac=b0:c4:20:00:00:00, ethmod=fbsd, ethdev=xlo
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=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
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: mac=b0:c4:20:00:00:01, ethmod=socket, ethdev=40000 # use localhost
ne2k: card=0, mac=b0:c4:20:00:00:01, ethmod=socket, ethdev=mymachine:40000
ne2k: mac=b0:c4:20:00:00:01, ethmod=slirp, script=slirp.conf, bootrom=ne2k_pci.rom
To support the Bochs/Etherboot pseudo-NIC, Bochs must be compiled with the --enable-pnic configure option. It accepts the same syntax (for mac, ethmod, ethdev, script, bootrom) and supports the same networking modules as the NE2000 adapter.
pnic: enabled=1, mac=b0:c4:20:00:00:00, ethmod=vnet
To support the Intel(R) 82540EM Gigabit Ethernet adapter, Bochs must be compiled with the --eanble-e1000 configure option. The E1000 accepts the same syntax (for card, mac, ethmod, ethdev, script, bootrom) and supports the same networking modules as the NE2000 adapter.
e1000: card=0, enabled=1, mac=52:54:00:12:34:56, ethmod=slirp, script=slirp.conf
This option controls the presence of the USB root hub which is a part of the i440FX PCI chipset. With the portX parameter you can connect devices to the hub (currently supported: 'mouse', 'tablet', 'keypad', 'keyboard', 'disk', 'cdrom', 'floppy', 'hub' and 'printer').
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. If the keyboard is selected, all key events are sent to the USB device.
To connect a disk image as a USB hardisk you can use the 'disk' device. Use the 'path' option in the optionsX parameter to specify the path to the image separated with a colon. To use other disk image modes similar to ATA disks the syntax 'path:mode:filename' must be used (see below).
To emulate a USB cdrom you can use the 'cdrom' device and the path to an ISO image or raw device name can be set with the 'path' option in the optionsX parameter also separated with a colon. An option to insert/eject media is available in the runtime configuration.
To emulate a USB floppy you can use the 'floppy' device and the path to a floppy image can be set with the 'path' option in the optionsX parameter separated with a colon. To use the VVFAT image mode similar to the legacy floppy the syntax 'path:vvfat:directory' must be used (see below). An option to insert/eject media is available in the runtime configuration.
The device name 'hub' connects an external hub with max. 8 ports (default: 4) to the root hub. To specify the number of ports you have to use the 'ports' option in the optionsX parameter with the value separated with a colon. Connecting devices to the external hub ports is only available in the runtime configuration.
The device 'printer' emulates the HP Deskjet 920C printer. The PCL data is sent to a file specified in the 'file' option with the optionsX parameter. The current code appends the PCL code to the file if the file already existed. The output file can be changed at runtime.
The optionsX parameter can be used to assign specific options to the device connected to the corresponding USB port. The option 'speed' can be used to set the speed reported by device ('low', 'full', 'high' or 'super'). The available speed choices depend on both HC and device. The option 'debug' turns on debug output for the device at connection time. The option 'pcap' turns on packet logging in PCAP format. For the USB 'disk' device the optionsX parameter can be used to specify an alternative redolog file (journal) of some image modes. For 'vvfat' mode USB disks the optionsX parameter can be used to specify the disk size (range 128M ... 128G). If the size is not specified, it defaults to 504M. For the USB 'floppy' device the optionsX parameter can be used to specify an alternative device ID to be reported. Currently only the model "teac" is supported (can fix hw detection in some guest OS). The USB floppy also accepts the parameter "write_protected" with valid values 0 and 1 to select the access mode (default is 0).
usb_uhci: port1=mouse, port2=disk, options2="path:usbstick.img"
usb_uhci: port1=hub, options1="ports:6"
usb_uhci: port2=disk, options2="path:undoable:usbdisk.img, journal:u.redolog"
usb_uhci: port2=disk, options2=""path:usbdisk2.img, sect_size:1024"
usb_uhci: port2=disk, options2="path:vvfat:vvfat, debug, speed:full"
usb_uhci: port2=cdrom, options2="path:image.iso"
usb_uhci: port1=printer, options1="file:printdata.bin"
usb_uhci: port2=floppy, options2="path:vvfat:diskette, model:teac"
This option controls the presence of the USB OHCI host controller with a 2-port hub. The portX parameter accepts the same device types with the same syntax as the UHCI controller (see above). The optionsX parameter is also available on OHCI.
This option controls the presence of the USB EHCI host controller with a 6-port hub. The portX parameter accepts the same device types with the same syntax as the UHCI controller (see above). The optionsX parameter is also available on EHCI.
usb_ehci: enabled=1, port1=tablet, options1="speed:high"
This option controls the presence of the USB xHCI host controller with a 4-port hub. The portX parameter accepts the same device types with the same syntax as the UHCI controller (see above). The optionsX parameter is also available on xHCI. NOTE: port 1 and 2 are USB3 and only support super-speed devices, but port 3 and 4 are USB2 and support speed settings low, full and high.
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 and not maintained yet.
This program is distributed under the terms of the GNU Lesser General Public License as published by the Free Software Foundation. See the LICENSE and COPYING files located in /usr/share/doc/bochs/ for details on the license and the lack of warranty.
The latest version of this program can be found at:
bochs(1), bochs-dlx(1), bximage(1)
The Bochs IA-32 Emulator site on the World Wide Web: http://bochs.sourceforge.net Online Bochs Documentation http://bochs.sourceforge.net/doc/docbook
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 under "Feedback".
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.