The tool dmidecode reads the system DMI table to display BIOS and hardware information of the server. Apart from getting current configuration of the system, you can also get information about maximum supported interface slots and memory capacity. dmidecodeis able to give information about the current RAM size on the system and the maximum RAM size supported by the system.
This article will provide you with some practicale tips how to use dmidecode if you do need details on your computer system and the motherboard manual is not available.
1. The dmidecode Command
The DMI table (Desktop Management interface) contains standardised information about computer systems. The Distributed Management Task Force provides intormation abaout the DMI specification and the SMBIOS specification.
Hint: dmidecode accesses memory areas of your system that do require access permissions of privileged users, e.g. the root account. Some Unix/Linux distributions do not provide the password of the root account. In these cases you may use the command sudo to execute single commands in the context of the root account.
The following output shows the principle set-up of the records:
Handle 0x0002, DMI type 2, 8 bytes. Base Board Information
Manufacturer: Intel
Product Name: C440GX+
Version: 727281-001
Serial Number: INCY92700942
Each record has:
- A handle. This is a unique identifier, which allows records to reference each other. For example, processor records usually reference cache memory records using their handles.
- A type. The SMBIOS specification defines different types of elements a computer can be made of. In this example, the type is 2, which means that the record contains “Base Board Information”.
- A size. Each record has a 4-byte header (2 for the handle, 1 for the type, 1 for the size), the rest is used by the record data. This value doesn’t take text strings into account (these are placed at the end of the record), so the actual length of the record may be (and is often) greater than the displayed value.
- Decoded values. The information presented of course depends on the type of record. Here, we learn about the board’s manufacturer, model, version and serial number.
Sample output of the command:
$ sudo dmidecode | head -18
# dmidecode 2.9
SMBIOS 2.3 present.
61 structures occupying 1884 bytes.
Table at 0x000F0450.
Handle 0xDA00, DMI type 218, 53 bytes
OEM-specific Type
Header and Data:
DA 35 00 DA B2 00 17 0B 0E 18 00 00 80 00 80 01
00 02 80 02 80 01 00 00 A0 00 A0 01 00 58 00 58
00 01 00 59 00 59 00 01 00 05 80 05 80 01 00 FF
FF 00 00 00 00
Handle 0xDA01, DMI type 218, 17 bytes
OEM-specific Type
Header and Data:
DA 11 01 DA B2 00 17 0B 0E 18 00 FF FF 00 00 00
00
1.1. DMI types
Each hardware component is organized in a separate records with definite type id’s. The DMI specification defines DMI types as follows:
Type Information
----------------------------------------
0 BIOS
1 System
2 Base Board
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
126 Disabled components
127 EOF (End Of File) marker
128-255 OEM-specific data
Instead of requesting data via type id’s dmidecode provides a number of keywords. Each keyword is equivalent to a list of type numbers:
Keyword Types
──────────────────────────────
bios 0, 13
system 1, 12, 15, 23, 32
baseboard 2, 10
chassis 3
processor 4
memory 5, 6, 16, 17
cache 7
connector 8
slot 9
The following examples show you how to use type id’s and keywords:
# request details about the BIOS $ dmidecode --type 0 # request details about the BIOS language $ dmidecode --type 13 # do the same using the keyword 'BIOS' $ dmidecode --type BIOS
1.2. Fetch values for scripting
If you are interested in using dmidecode in your own scripts there are a number of system properties that can be requested by using one of the following list of keywords:
Valid string keywords are: bios-vendor bios-version bios-release-date system-manufacturer system-product-name system-version system-serial-number system-uuid baseboard-manufacturer baseboard-product-name baseboard-version baseboard-serial-number baseboard-asset-tag chassis-manufacturer chassis-type chassis-version chassis-serial-number chassis-asset-tag processor-family processor-manufacturer processor-version processor-frequency
To fetch details about your processor you may use the following commands:
# sample session with hardware specific output $ dmidecode -s processor-family Pentium 4 $ dmidecode -s processor-frequency 1800 MHz
1.3. Get information on physical memory (RAM)
To fetch details on the maximum supported memory capacity you have to fetch the data for DMI type id 16. Details about the present RAM modules detected by the BIOS are available in DMI type id 17.
The following example shows a sample session where the memory configuration of a computer is requested. Pre-empting the result, there is a maximum supported capacity of 4 GB RAM with a present configuration of 4×1GB RAM in Slots 0…3. Especially type id 17 contains a lot of hardware specific details, that are not available on labels at your mainboard and RAM modules.
# fetch data about the maximum supported RAM configuration
$ dmidecode -t 16
SMBIOS 2.3 present.
Handle 0x0043, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 4 GB <--- Maximum supported RAM !!!
Error Information Handle: Not Provided
Number Of Devices: 4 <--- number of available extension slots
# ----------------
# fetch data on the number and the type of plugged-in RAM modules
# that have been detected by the BIOS
$ dmidecode -t 17
SMBIOS 2.3 present.
Handle 0x0044, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0043
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 1024 MB <--- Slot 0 contains a 1 GB RAM DIMM
Form Factor: DIMM
Set: None
Locator: A0
Bank Locator: Bank0/1
Type: Unknown
Type Detail: None
Speed: 333 MHz (3.0 ns)
Manufacturer: None
Serial Number: None
Asset Tag: None
Part Number: None
Handle 0x0045, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0043
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 1024 MB <--- Slot 1 contains a 1 GB RAM DIMM
Form Factor: DIMM
Set: None
Locator: A1
Bank Locator: Bank2/3
Type: Unknown
Type Detail: None
Speed: 333 MHz (3.0 ns)
Manufacturer: None
Serial Number: None
Asset Tag: None
Part Number: None
Handle 0x0046, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0043
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 1024 MB <--- Slot 2 contains a 1 GB RAM DIMM
Form Factor: DIMM
Set: None
Locator: A2
Bank Locator: Bank4/5
Type: Unknown
Type Detail: None
Speed: 333 MHz (3.0 ns)
Manufacturer: None
Serial Number: None
Asset Tag: None
Part Number: None
Handle 0x0047, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x0043
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 1024 MB <--- Slot 3 contains a 1 GB RAM DIMM
Form Factor: DIMM
Set: None
Locator: A3
Bank Locator: Bank6/7
Type: Unknown
Type Detail: None
Speed: 333 MHz (3.0 ns)
Manufacturer: None
Serial Number: None
Asset Tag: None
Part Number: None
1.4. Get information on your BIOS
Utilizing the keyword BIOS you will get an overview about the BIOS installed in your computer system:
$ dmidecode -t BIOS
SMBIOS 2.3 present.
Handle 0x0000, DMI type 0, 20 bytes
BIOS Information
Vendor: Phoenix Technologies, LTD
Version: ASUS A8N-SLI DELUXE ACPI BIOS Revision 1016
Release Date: 12/01/2005
Address: 0xE0000
Runtime Size: 128 kB
ROM Size: 512 kB
Characteristics:
PCI is supported
PNP is supported
APM is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
BIOS ROM is socketed
EDD is supported
5.25"/360 KB floppy services are supported (int 13h)
5.25"/1.2 MB floppy services are supported (int 13h)
3.5"/720 KB floppy services are supported (int 13h)
3.5"/2.88 MB floppy services are supported (int 13h)
Print screen service is supported (int 5h)
8042 keyboard services are supported (int 9h)
Serial services are supported (int 14h)
Printer services are supported (int 17h)
CGA/mono video services are supported (int 10h)
ACPI is supported
USB legacy is supported
LS-120 boot is supported
ATAPI Zip drive boot is supported
BIOS boot specification is supported
Handle 0x0042, DMI type 13, 22 bytes
BIOS Language Information
Installable Languages: 3
n|US|iso8859-1
n|US|iso8859-1
r|CA|iso8859-1
Currently Installed Language: n|US|iso8859-1
1.5. Get information on your processors
Utilizing the keyword PROCESSOR you will get an overview about your CPU’s and all supported features:
$ dmidecode --type processor
SMBIOS 2.3 present.
Handle 0x0004, DMI type 4, 35 bytes
Processor Information
Socket Designation: Socket 939
Type: Central Processor
Family: Athlon 64
Manufacturer: AMD
ID: 32 0F 02 00 FF FB 8B 17
Signature: Family 15, Model 35, Stepping 2
Flags:
FPU (Floating-point unit on-chip)
VME (Virtual mode extension)
DE (Debugging extension)
PSE (Page size extension)
TSC (Time stamp counter)
MSR (Model specific registers)
PAE (Physical address extension)
MCE (Machine check exception)
CX8 (CMPXCHG8 instruction supported)
APIC (On-chip APIC hardware supported)
SEP (Fast system call)
MTRR (Memory type range registers)
PGE (Page global enable)
MCA (Machine check architecture)
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PAT (Page attribute table)
PSE-36 (36-bit page size extension)
CLFSH (CLFLUSH instruction supported)
MMX (MMX technology supported)
FXSR (Fast floating-point save and restore)
SSE (Streaming SIMD extensions)
SSE2 (Streaming SIMD extensions 2)
HTT (Hyper-threading technology)
Version: AMD Athlon(tm) 64 X2 Dual Core Processor 4400+
Voltage: 1.3 V
External Clock: 200 MHz
Max Speed: 3700 MHz
Current Speed: 2200 MHz
Status: Populated, Enabled
Upgrade: Socket 939
L1 Cache Handle: 0x000A
L2 Cache Handle: 0x000B
L3 Cache Handle: Not Provided
Serial Number:
Asset Tag:
Part Number:
1.6. Get information on Manufacturer, Model and Serial number of the equipment
The keyword SYSTEM subsumes a number of DMI type id’s in a single command. Take a look on the following sample output:
$ dmidecode --type system
SMBIOS 2.3 present.
Handle 0x0100, DMI type 1, 25 bytes
System Information
Manufacturer: Dell Computer Corporation
Product Name: OptiPlex GX240
Version: Not Specified
Serial Number: 5182J0J
UUID: 44454C4C-3100-1038-8032-B5C04F4A304A
Wake-up Type: Power Switch
Handle 0x0F00, DMI type 15, 31 bytes
System Event Log
Area Length: 2049 bytes
Header Start Offset: 0x0000
Header Length: 16 bytes
Data Start Offset: 0x0010
Access Method: Memory-mapped physical 32-bit address
Access Address: 0xFFF82000
Status: Valid, Not Full
Change Token: 0x0000000E
Header Format: Type 1
Supported Log Type Descriptors: 4
Descriptor 1: POST error
Data Format 1: POST results bitmap
Descriptor 2: System limit exceeded
Data Format 2: System management
Descriptor 3: Log area reset/cleared
Data Format 3: None
Descriptor 4: Multi-bit ECC memory error
Data Format 4: Handle
Handle 0x2000, DMI type 32, 11 bytes
System Boot Information
Status: No errors detected
if (document.currentScript) {