** INTRODUCTION **
Dmidecode reports information about your system's hardware as described in your system BIOS according to the SMBIOS/DMI standard. This information typically includes system manufacturer, model name, serial number, BIOS version, asset tag as well as a lot of other details of varying level of interest and reliability depending on the manufacturer. This will often include usage status for the CPU sockets, expansion slots (e.g. AGP, PCI, ISA) and memory module slots, and the list of I/O ports (e.g. serial, parallel, USB).
Part of the dmidecode code can be found in the Linux kernel, where DMI data is used to enable or disable specific portions of code depending on the specific hardware. Thus, one use of dmidecode is for kernel developers to detect system "signatures" and add them to the kernel source code when needed.
Beware that DMI data have proven to be too unreliable to be blindly trusted. Dmidecode does not scan your hardware, it only reports what the BIOS told it to.
** INSTALLATION **
The home web page for dmidecode is hosted on Savannah:
You will find the latest version (including CVS) there, as well as fresh news and other interesting material, such as a list of related projects and articles.
This program was first written for Linux, and has since been reported to work on FreeBSD, NetBSD, BeOS and Cygwin as well.
There's no configure script, so simply run "make" to build dmidecode, and "make install" to install it. You also can use "make uninstall" to remove all files you installed. By default, files are installed in /usr/local but you can change this behavior by editing the Makefile file and setting prefix to wherever you want. You may change the C compiler and the compilation flags as well.
Optionally, you can run "make strip" prior to "make install" if you want smaller binaries. However, know that this will prevent any further attempt to debug programs.
Two parameters can be set in the Makefile file to make dmidecode work on non-i386 systems. They should be used if your system uses the big endian byte ordering (Motorola) or doesn't support unaligned memory accesses, respectively. For example, compiling for a SPARC processor would require both. Note that this hasn't been much tested though, because the data manipulated by dmidecode and the other tools is only found on i386 and neighbour architectures (x86_64, ia64) anyway.
** DOCUMENTATION **
Each tool has a manual page, found in the "man" subdirectory. Manual pages are installed by "make install". See these manual pages for command line interface details and tool specific information.
For an history of the changes made to dmidecode, see the CHANGELOG file.
If you need help, your best chances are to visit the web page (see the INSTALLATION section above) or to get in touch with the developers directly. Have a look at the AUTHORS file and contact one of the maintainers.
If you want to help with the development of dmidecode, please consider joining the dmidecode-devel discussion list: http://lists.nongnu.org/mailman/listinfo/dmidecode-devel
The most common problems are detailed in the COMMON PROBLEMS section right below.
** COMMON PROBLEMS **
MODEL SPECIFIC ISSUES
Dmidecode used not to work on IBM T-series laptops nor on Fujitsu-Siemens S-series laptops under Linux. This was due to the fact that the DMI table is at a memory location we couldn't seem to reach through /dev/mem. Although I believe this reveals a problem in the Linux kernel, which should be fixed, a workaround was found by Chad Smith, and we are using it for now. See the IA-64 subsection below for more details. I posted about this problem on the LKML but did not have any answer. Since then, the list of affected systems was extended to IBM X-series laptops and xSeries x445 servers.
Dmidecode used to have problems on IA-64 systems. The first reason for this is that dmidecode accesses the DMI table through /dev/mem, and reading this file on an IA-64 system sometimes leads to a crash. A second reason is that the method for locating the above-mentioned table differs on IA-64 (compared to x86), so dmidecode was likely to miss the table entry point. This complex issue was reported by Glen Foster and Chad Smith from HP. We have since been working on a solution, and dmidecode now supports IA-64 systems. Chad Smith noticed that, for some obscure reason, accessing the /dev/mem file using mmap() instead of read() would work. Then, he wrote a patch to export the DMI table address from the internal EFI table to /proc, so dmidecode doesn't have to scan /dev/mem for it anymore. This patch was since integrated into the main ia64 patch. Finally, I added the required code to make it all work. So, in order to have dmidecode work on your IA-64 system, you need two things:
- dmidecode version 2.2 or later;
- an ia64 patched 2.4 kernel, using linux-2.4.21-ia64-030702.diff or any later version, or a 2.6 kernel. Chad Smith tested dmidecode successfully on two different IA-64 systems, and successes have been reported by other users too. Non-Linux systems are not supported.
Note that mmap() is now used by default wherever possible, since this seems to solve a number of problems. This default behavior can be changed in config.h. Just to make sure this is clear, mmap() is not used for performance reasons but to increase the number of systems on which dmidecode can be successfully run. See the IA-64 subsection above for details.
Dmidecode was reported to work under Cygwin. It seems that /dev/mem doesn't work properly before version 1.5.10 though, so you will need to use at least this version.
** MISCELLANEOUS TOOLS **
Three other tools come along with dmidecode: biosdecode, ownership and vpddecode.
This one prints all BIOS related information it can find in /dev/mem. It used to be part of dmidecode itself, but as dmidecode was growing, we felt that the non-DMI part had to be moved to a separate tool.
This tool was written on a request by Luc Van de Velde for use with Novell tools in his company. It retrieves the "ownership tag" that can be set on most Compaq computers. Since it uses the same mechanisms dmidecode and biosdecode use, and could be of some use for other people as well, we decided to make it part of the project.
This tool prints the contents of the "vital product data" structure as found in most IBM computers. It has a lookup table for the machine name and a command line interface.