Dmidecode is a free and open source utility we can use to retrieve hardware information on Linux. The tool is available in the repositories of all the major Linux distributions, and is able to inspect and dump the content of the SMBIOS table.
In this tutorial we learn how to install dmidecode, and how to use it to retrieve information about the hardware configuration on Linux.
In this tutorial you will learn:
- How to install dmidecode on the major Linux distributions
- How information records reported by dmidecode are organized
- How to use dmidecode to retrieve specific hardware information
| Category | Requirements, Conventions or Software Version Used |
|---|---|
| System | Distribution independent |
| Software | dmidecode |
| Other | None |
| Conventions | # – requires given linux-commands to be executed with root privileges either directly as a root user or by use of sudo command $ – requires given linux-commands to be executed as a regular non-privileged user |
Installation
The dmidecode tool is available in the default repositories of all the major Linux distributions; chances are the utility is already installed in your system. If for some reasons it is not, here are the commands we can use it to install it on Archlinux and distributions member of the Fedora and Debian family:
| DISTRIBUTION | COMMAND |
|---|---|
| Fedora/Rhel/Rocky | $ sudo dnf install dmidecode |
| Debian/Ubuntu | $ sudo apt install dmidecode |
| Archlinux | $ sudo pacman -S dmidecode |
The DMI/SMBIOS table
DMI is the acronym of Desktop Management Interface; SMBIOS, instead stands for: System Management Bios. The two standards are developed by the Desktop MAnagement Task Force (DMTF). Their purpose is to let an Operating System easily access hardware information.
On boot, the table containing those information is loaded in memory, and can be parsed by dedicated utilities like dmidecode. The table contains information such as the hardware vendor, configuration, serial numbers, list of ports, etc.
Using dmidecode
Let’s see some examples of how to use the dmidecode tool. When the utility is invoked without any options, it just produces an output which contains all the information it is able to retrieve. Information are organized in records. Here is an example:
$ sudo dmidecode [...] Handle 0x0003, DMI type 16, 23 bytes Physical Memory Array Location: System Board Or Motherboard Use: System Memory Error Correction Type: None Maximum Capacity: 32 GB Error Information Handle: Not Provided [...]
[ADLSOT2]The one above is, for obvious reasons, just a little extract of the output produced by the utility, and describes the memory configuration on my machine. Let’s analyze how the record is composed. Each record has:
- A Handle or unique identifier (0x0003 in this case)
- A DMI type, which in this case is 16, which refers to the Physical Memory Array. The SMBIOS specification encodes and associates a list of types in a table (more on this later). We can instruct dmidecode to return information related on specific types only.
- The Size used to store the record, which, in this case is 23 bytes.
- The actual values of the record, which varies depending on the record itself.
The DMI Types
As we already said, information are organized in types. The table below contains their associations:
| DMI TYPE | INFORMATION |
|---|---|
| 0 | Bios |
| 1 | System |
| 2 | Baseboard |
| 3 | Chassis |
| 4 | Processor |
| 5 | Memory Controller |
| 6 | Memory Module |
| 7 | Cache |
| 8 | Port Connector |
| 9 | System Slots |
| 10 | On Board Devices |
| 11 | OEM Strings |
| 12 | System Configuration Options |
| 13 | Bios Language |
| 14 | Group Associations |
| 15 | System Event Log |
| 16 | Physical Memory Array |
| 17 | Memory Device |
| 18 | 32-bit Memory Error |
| 19 | Memory Array Mapped Address |
| 20 | Memory Device Mapped Address |
| 21 | Built-in Pointing Device |
| 22 | Portable Battery |
| 23 | System Reset |
| 24 | Hardware Security |
| 25 | System Power Controls |
| 26 | Voltage Probe |
| 27 | Cooling Device |
| 28 | Temperature Probe |
| 29 | Electrical Current Probe |
| 30 | Out-of-band Remote Access |
| 31 | Boot Integrity Services |
| 32 | System Boot |
| 33 | 64-bit Memory Error |
| 34 | Management Device |
| 35 | Management Device Component |
| 36 | Management Device Threshold Data |
| 37 | Memory Channel |
| 38 | IPMI Device |
| 39 | Power Supply |
| 40 | Additional Information |
| 41 | Onboard Devices Extended Information |
| 42 | Management Controller Host Interface |
DMI Types can be used to retrieve and filter specific information with dmidecode. All we have to do is to invoke the utility with the -t option (short for --type), and provide the DMI type we want to query as argument. Supposing we want to gather memory devices (17) information, we would run:
$ sudo dmidecode -t 17
On my machine, the output produced by the command, is the following:
# dmidecode 3.4 Getting SMBIOS data from sysfs. SMBIOS 3.0.0 present. Handle 0x0004, DMI type 17, 40 bytes Memory Device Array Handle: 0x0003 Error Information Handle: Not Provided Total Width: 64 bits Data Width: 64 bits Size: 8 GB Form Factor: SODIMM Set: None Locator: ChannelA-DIMM0 Bank Locator: BANK 0 Type: DDR4 Type Detail: Synchronous Unbuffered (Unregistered) Speed: 2133 MT/s Manufacturer: Micron Serial Number: 00000000 Asset Tag: None Part Number: 4ATS1G64HZ-2G3A1 Rank: 1 Configured Memory Speed: 2133 MT/s Minimum Voltage: Unknown Maximum Voltage: Unknown Configured Voltage: 1.2 V Handle 0x0005, DMI type 17, 40 bytes Memory Device Array Handle: 0x0003 Error Information Handle: Not Provided Total Width: Unknown Data Width: Unknown Size: No Module Installed Form Factor: Unknown Set: None Locator: ChannelB-DIMM0 Bank Locator: BANK 2 Type: Unknown
As you can see, there are two DDR4 memory banks available, and only one of 8GB is used (soldered). We can see that other precious information as the “Part Number” are also reported: this can be useful in case we want to be sure we buy compatible hardware.
Multiple DMI types can be query we just one command: we can either repeat the option, or provide a comma-separated list of type numbers as argument. To query both BIOS (0) and memory devices (17), for example, we would run:
$ sudo dmidecode --type 0,17
Conclusions
In this tutorial we learned how to install and use the dmidecode utility to retrieve hardware information on Linux. The tool is open source and available on all the major distributions: it is able to read and parse the SMBIOS table. We saw how each record displayed by the application is composed, and how to query specific information, which are organized in DMI Types.