1DMIDECODE(8) System Manager's Manual DMIDECODE(8)
2
6 dmidecode - DMI table decoder
7
9 dmidecode [OPTIONS]
10
13 dmidecode is a tool for dumping a computer's DMI (some say SMBIOS) ta‐
14 ble contents in a human-readable format. This table contains a descrip‐
15 tion of the system's hardware components, as well as other useful
16 pieces of information such as serial numbers and BIOS revision. Thanks
17 to this table, you can retrieve this information without having to
18 probe for the actual hardware. While this is a good point in terms of
19 report speed and safeness, this also makes the presented information
20 possibly unreliable.
21 The DMI table doesn't only describe what the system is currently made
23 of, it also can report the possible evolutions (such as the fastest
24 supported CPU or the maximal amount of memory supported).
25 SMBIOS stands for System Management BIOS, while DMI stands for Desktop
27 Management Interface. Both standards are tightly related and developed
28 by the DMTF (Desktop Management Task Force).
29 As you run it, dmidecode will try to locate the DMI table. It will
31 first try to read the DMI table from sysfs, and next try reading
32 directly from memory if sysfs access failed. If dmidecode succeeds in
33 locating a valid DMI table, it will then parse this table and display a
34 list of records like this one:
35 Handle 0x0002, DMI type 2, 8 bytes. Base Board Information
37 Manufacturer: Intel
38 Product Name: C440GX+
39 Version: 727281-001
40 Serial Number: INCY92700942
41 Each record has:
43 · A handle. This is a unique identifier, which allows records to refer‐
45 ence each other. For example, processor records usually reference
46 cache memory records using their handles.
47 · A type. The SMBIOS specification defines different types of elements
49 a computer can be made of. In this example, the type is 2, which
50 means that the record contains "Base Board Information".
51 · A size. Each record has a 4-byte header (2 for the handle, 1 for the
53 type, 1 for the size), the rest is used by the record data. This
54 value doesn't take text strings into account (these are placed at the
55 end of the record), so the actual length of the record may be (and is
56 often) greater than the displayed value.
57 · Decoded values. The information presented of course depends on the
59 type of record. Here, we learn about the board's manufacturer, model,
60 version and serial number.
61
64 -d, --dev-mem FILE
65 Read memory from device FILE (default: /dev/mem)
66 -q, --quiet
68 Be less verbose. Unknown, inactive and OEM-specific entries are
69 not displayed. Meta-data and handle references are hidden.
70 -s, --string KEYWORD
72 Only display the value of the DMI string identified by KEYWORD.
73 KEYWORD must be a keyword from the following list: bios-vendor,
74 bios-version, bios-release-date, system-manufacturer, system-
75 product-name, system-version, system-serial-number, system-uuid,
76 system-family, baseboard-manufacturer, baseboard-product-name,
77 baseboard-version, baseboard-serial-number, baseboard-asset-tag,
78 chassis-manufacturer, chassis-type, chassis-version, chassis-
79 serial-number, chassis-asset-tag, processor-family, processor-
80 manufacturer, processor-version, processor-frequency. Each key‐
81 word corresponds to a given DMI type and a given offset within
82 this entry type. Not all strings may be meaningful or even
83 defined on all systems. Some keywords may return more than one
84 result on some systems (e.g. processor-version on a multi-pro‐
85 cessor system). If KEYWORD is not provided or not valid, a list
86 of all valid keywords is printed and dmidecode exits with an
87 error. This option cannot be used more than once.
88 Note: on Linux, most of these strings can alternatively be read
90 directly from sysfs, typically from files under
91 /sys/devices/virtual/dmi/id. Most of these files are even read‐
92 able by regular users.
93 -t, --type TYPE
95 Only display the entries of type TYPE. TYPE can be either a DMI
96 type number, or a comma-separated list of type numbers, or a
97 keyword from the following list: bios, system, baseboard, chas‐
98 sis, processor, memory, cache, connector, slot. Refer to the DMI
99 TYPES section below for details. If this option is used more
100 than once, the set of displayed entries will be the union of all
101 the given types. If TYPE is not provided or not valid, a list
102 of all valid keywords is printed and dmidecode exits with an
103 error.
104 -u, --dump
106 Do not decode the entries, dump their contents as hexadecimal
107 instead. Note that this is still a text output, no binary data
108 will be thrown upon you. The strings attached to each entry are
109 displayed as both hexadecimal and ASCII. This option is mainly
110 useful for debugging.
111 --dump-bin FILE
113 Do not decode the entries, instead dump the DMI data to a file
114 in binary form. The generated file is suitable to pass to
115 --from-dump later.
116 --from-dump FILE
118 Read the DMI data from a binary file previously generated using
119 --dump-bin.
120 --no-sysfs
122 Do not attempt to read DMI data from sysfs files. This is mainly
123 useful for debugging.
124 --oem-string N
126 Only display the value of the OEM string number N. The first OEM
127 string has number 1. With special value "count", return the num‐
128 ber of OEM strings instead.
129 -h, --help
131 Display usage information and exit
132 -V, --version
134 Display the version and exit
135 Options --string, --type, --dump-bin and --oem-string determine the
137 output format and are mutually exclusive.
138 Please note in case of dmidecode is run on a system with BIOS that
140 boasts new SMBIOS specification, which is not supported by the tool
141 yet, it will print out relevant message in addition to requested data
142 on the very top of the output. Thus informs the output data is not
143 reliable.
144
147 The SMBIOS specification defines the following DMI types:
148 Type Information
151 ────────────────────────────────────────────
152 0 BIOS
153 1 System
154 2 Baseboard
155 3 Chassis
156 4 Processor
157 5 Memory Controller
158 6 Memory Module
159 7 Cache
160 8 Port Connector
161 9 System Slots
162 10 On Board Devices
163 11 OEM Strings
164 12 System Configuration Options
165 13 BIOS Language
166 14 Group Associations
167 15 System Event Log
168 16 Physical Memory Array
169 17 Memory Device
170 18 32-bit Memory Error
171 19 Memory Array Mapped Address
172 20 Memory Device Mapped Address
173 21 Built-in Pointing Device
174 22 Portable Battery
175 23 System Reset
176 24 Hardware Security
177 25 System Power Controls
178 26 Voltage Probe
179 27 Cooling Device
180 28 Temperature Probe
181 29 Electrical Current Probe
182 30 Out-of-band Remote Access
183 31 Boot Integrity Services
184 32 System Boot
185 33 64-bit Memory Error
186 34 Management Device
187 35 Management Device Component
188 36 Management Device Threshold Data
189 37 Memory Channel
190 38 IPMI Device
191 39 Power Supply
192 40 Additional Information
193 41 Onboard Devices Extended Information
194 42 Management Controller Host Interface
195 Additionally, type 126 is used for disabled entries and type 127 is an
197 end-of-table marker. Types 128 to 255 are for OEM-specific data.
198 dmidecode will display these entries by default, but it can only decode
199 them when the vendors have contributed documentation or code for them.
200 Keywords can be used instead of type numbers with --type. Each keyword
202 is equivalent to a list of type numbers:
203 Keyword Types
206 ──────────────────────────────
207 bios 0, 13
208 system 1, 12, 15, 23, 32
209 baseboard 2, 10, 41
210 chassis 3
211 processor 4
212 memory 5, 6, 16, 17
213 cache 7
214 connector 8
215 slot 9
216 Keywords are matched case-insensitively. The following command lines
218 are equivalent:
219 · dmidecode --type 0 --type 13
221 · dmidecode --type 0,13
223 · dmidecode --type bios
225 · dmidecode --type BIOS
227
230 The binary dump files generated by --dump-bin and read using --from-
231 dump are formatted as follows:
232 · The SMBIOS or DMI entry point is located at offset 0x00. It is
234 crafted to hard-code the table address at offset 0x20.
235 · The DMI table is located at offset 0x20.
237
240 /dev/mem /sys/firmware/dmi/tables/smbios_entry_point (Linux only)
241 /sys/firmware/dmi/tables/DMI (Linux only)
242
244 More often than not, information contained in the DMI tables is inaccu‐
245 rate, incomplete or simply wrong.
246
248 Alan Cox, Jean Delvare
249
251 biosdecode(8), mem(4), ownership(8), vpddecode(8)
252dmidecode March 2012 DMIDECODE(8)