The PNPDUMP.8 manual

Dated 05 Jan 2001


pnpdump - Dump ISA Plug-And-Play devices resource information


pnpdump [ --help ] [ --config ] [ --script[=outputfile] ] [ --reset ] [ --ignorecsum ] [ --masks ] [ --dumpregs ] [ --max-realtime=t ] [ --version ] [ --debug-isolate ] [ --outputfile=outputfile] [ [ devs ] readport ]


pnpdump will scan all the ISA PnP cards, dumping their resource data to stdout. The resource data is supposed to be a description of the resources (IO ports, interrupts, DMA channels) that the card would like, or needs, to use to work. It is stored in a small ROM on the card, which can be read as part of the Plug and Play configuration process.

Note that some manufacturers are rather lax about the contents of this ROM, particularly if the card is not required for booting, so the resource data may not be accurate. As they also typically provide a DOS/Windows driver for the card, they really only need to be able to recognise it, as the driver can then complete the configuration.

The output of pnpdump is in a form that can be used by isapnp, except that the actual configuration statements are commented out. See isapnp.conf(5) for details of the format.

By default, pnpdump will reset all the Card Serial Numbers, then ISOLATE each one and allocate it a handle (Card Select Number). This process will include trying different readport addresses until a suitable one is found avoiding conflicts with other hardware. For a description of what the readport is, see the relevant entry in isapnp.conf(5). As of the isapnptools 1.12 release, any existing configuration settings will be unaffected.

If a single parameter is provided, this will be used as the minimum readport address to start scanning. This may be chosen to avoid an unfortunate conflict.

To skip the Isolation process, both additional parameters may be supplied:


devs is the number of PnP cards that the BIOS has found,
ISOLATEd and allocated CSNs to in the system. Note that if this is greater than the actual number of cards in the system, pnpdump will stop scanning when it receives a first serial identifier byte of 0xff (this is what happens when there isn't a card with that CSN).

If this parameter is provided, then pnpdump will not ISOLATE each card and assign CSNs, however, the readport provided must be the same as the one the BIOS used. This could be difficult to determine if it is not assigned via a BIOS setup screen.

readport is the address of the readport to use for the
Plug-And-Play access. The number base is determined by the format: a leading 0x implies hex, a leading 0 implies octal, otherwise decimal is assumed.

The address of the readport must be chosen to avoid any conflicts with existing (non Plug and Play) hardware, and must be in the range 0x203..0x3ff.

If the readport is specified without devs, then this is the minimum readport to use when scanning for a suitable one. Note that for the two parameter option to work, you must have a PnP BIOS which has already carried out the ISOLATION process correctly, and you must know what readport address the BIOS used.

pnpdump will run with real-time scheduling if possible to achieve the required IO timings. This will lock out all normal programs while it executes. In version 1.19 and later of isapnptools, pnpdump will only run in this mode for 5 seconds (or as set on the command line), it then reverts to standard scheduling like any other program. Previous versions should only be run from a standard console as ^C will kill it from there. If you run the command remotely (and X counts as remote), you will not be able to kill it as no other programs can run.


-h, --help
Show a help summary.
-c, --config
attempt to determine safe settings to which the devices can be set, and uncomment those settings in the output. pnpdump will use information in the /proc filesystem and the contents of the /etc/isapnp.gone file to discover system resources that have already been allocated, if these facilities are available on the system.

Note that if the resource allocation is impossible, pnpdump is not intelligent enough to realise this and may hang trying to find a solution.

-d, --dumpregs
this will cause pnpdump will dump all the standard configuration registers for each board.

Note that this dump is dumping the physical registers, and will thus show the settings that have been put in there by the BIOS, or some cards will put a default setting in. Unused registers read back as 0.

-D, --debug-isolate
this will cause pnpdump to output loads of extra information, showing the actual data received during the isolation process. You'll probably need the ISAPnP spec to work out what it means.
-i, --ignorecsum
this will cause pnpdump will ignore checksum errors when deciding if the readport address is good. Section 3.3.2 of the spec suggests that a bad checksum should cause the readport to be rejected. In reality, it seems to be possible for the checksum to be bad for reasons other than a readport address conflict, and in this situation all readport addresses will be rejected resulting in no boards found.

Using this flag allows the boards to still be found. Boards with a bad identifier checksum will have the identifier corrected by the resource data if the resource data identifier has a good checksum.

-r, --reset
Carry out a full configuration reset, rather than just resetting the CSNs. DANGEROUS as this could reset PnP boards in active use by the kernel, resulting in a lockup or worse.
-m, --masks
Print the lists of acceptable interrupts and direct memory access (DMA) channels as binary bitmasks. For example, print "IRQ mask 0x03" instead of "IRQ 1, 2, or 3".
-o, --outputfile=filename
write all output to the file specified, rather than stdout. This option is not available in the DOS version.
-t t, --max-realtime=t
Set the maximum time the process can run at real-time priority to t seconds. If t is set to 0, the timeout is disabled; in this case you must run the program from a normal text console to allow it to be aborted via control-C if it hangs. The default timeout is 5 seconds. After the timeout has expired, the process runs with normal scheduling, which means it may go a lot slower, but will prevent locking up the comupter (if it hangs while running under X windows for example). This option is only available when compiled with real time scheduling support.
-s, --script[=outputscript]
write a shell script to the specified file that can be used to configure the system based on what ISA PnP boards were found and how they were configured. Note that the script generated uses array variables, so you need bash version 2 and later to run them. This option is not available in the DOS version.

If --script is specified without an argument, then the script is piped (using popen) directly into a shell (sh) process. This is really useful only with --config.

For each card, the script tries to execute the shell script /etc/pnp/config-scripts/isa/PRODUCT_ID or, failing that, /usr/share/pnp/config-scripts/isa/PRODUCT_ID. The generated shell script will try the compatible device ID's if any can any are in the ISA PnP information and no script for the device itself can be found.

The /usr/share directory contents are the standard location, while the /etc directory is for you to put your customized versions of these scripts. You should write these shell scripts to generate the file /etc/conf.modules.isapnp at boot time, and then do something like "cat /etc/conf.modules.isapnp /etc/conf.modules.base > /etc/conf.modules", so that you can automatically configure the modules for the devices that you have.

-v, --version
Print the isapnptools version number on stderr.


The executable.
The resting place of the editted output. /etc/isapnp.gone The standard place for describing resources that are unavailable, but not flagged as such in /proc/* etc. The format of this file is explained in the example provided with isapnptools.


If the resource allocation is impossible, pnpdump -c is not intelligent enough to realise this and may hang trying to find a solution.

Check for latest information and FAQ.

If you think you have found one not mentioned in the latest version, please send a report to


This program can reset all your Plug-and-Play devices. It can also lock up your machine. Use at your own risk.


pnpdump has been written by Peter Fox <>, the creator and maintainer of isapnptools.


The latest version of the sources may be obtained by ftp from

Or follow the pointer from my web page at


Plug and Play ISA Specification, Version 1.0a, May 5, 1994. Available from


isapnp(8), isapnp.conf(5)