1DMIDECODE(8) System Manager's Manual DMIDECODE(8)
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6 dmidecode - DMI table decoder
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9 dmidecode [OPTIONS]
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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 -H, --handle HANDLE
106 Only display the entry whose handle matches HANDLE. HANDLE is a
107 16-bit integer.
108 -u, --dump
110 Do not decode the entries, dump their contents as hexadecimal
111 instead. Note that this is still a text output, no binary data
112 will be thrown upon you. The strings attached to each entry are
113 displayed as both hexadecimal and ASCII. This option is mainly
114 useful for debugging.
115 --dump-bin FILE
117 Do not decode the entries, instead dump the DMI data to a file
118 in binary form. The generated file is suitable to pass to
119 --from-dump later.
120 --from-dump FILE
122 Read the DMI data from a binary file previously generated using
123 --dump-bin.
124 --no-sysfs
126 Do not attempt to read DMI data from sysfs files. This is mainly
127 useful for debugging.
128 --oem-string N
130 Only display the value of the OEM string number N. The first OEM
131 string has number 1. With special value "count", return the num‐
132 ber of OEM strings instead.
133 -h, --help
135 Display usage information and exit
136 -V, --version
138 Display the version and exit
139 Options --string, --type, --dump-bin and --oem-string determine the
141 output format and are mutually exclusive.
142 Please note in case of dmidecode is run on a system with BIOS that
144 boasts new SMBIOS specification, which is not supported by the tool
145 yet, it will print out relevant message in addition to requested data
146 on the very top of the output. Thus informs the output data is not
147 reliable.
148
151 The SMBIOS specification defines the following DMI types:
152 Type Information
155 ────────────────────────────────────────────
156 0 BIOS
157 1 System
158 2 Baseboard
159 3 Chassis
160 4 Processor
161 5 Memory Controller
162 6 Memory Module
163 7 Cache
164 8 Port Connector
165 9 System Slots
166 10 On Board Devices
167 11 OEM Strings
168 12 System Configuration Options
169 13 BIOS Language
170 14 Group Associations
171 15 System Event Log
172 16 Physical Memory Array
173 17 Memory Device
174 18 32-bit Memory Error
175 19 Memory Array Mapped Address
176 20 Memory Device Mapped Address
177 21 Built-in Pointing Device
178 22 Portable Battery
179 23 System Reset
180 24 Hardware Security
181 25 System Power Controls
182 26 Voltage Probe
183 27 Cooling Device
184 28 Temperature Probe
185 29 Electrical Current Probe
186 30 Out-of-band Remote Access
187 31 Boot Integrity Services
188 32 System Boot
189 33 64-bit Memory Error
190 34 Management Device
191 35 Management Device Component
192 36 Management Device Threshold Data
193 37 Memory Channel
194 38 IPMI Device
195 39 Power Supply
196 40 Additional Information
197 41 Onboard Devices Extended Information
198 42 Management Controller Host Interface
200 Additionally, type 126 is used for disabled entries and type 127 is an
202 end-of-table marker. Types 128 to 255 are for OEM-specific data.
203 dmidecode will display these entries by default, but it can only decode
204 them when the vendors have contributed documentation or code for them.
205 Keywords can be used instead of type numbers with --type. Each keyword
207 is equivalent to a list of type numbers:
208 Keyword Types
211 ──────────────────────────────
212 bios 0, 13
213 system 1, 12, 15, 23, 32
214 baseboard 2, 10, 41
215 chassis 3
216 processor 4
217 memory 5, 6, 16, 17
218 cache 7
219 connector 8
220 slot 9
221 Keywords are matched case-insensitively. The following command lines
223 are equivalent:
224 · dmidecode --type 0 --type 13
226 · dmidecode --type 0,13
228 · dmidecode --type bios
230 · dmidecode --type BIOS
232
235 The binary dump files generated by --dump-bin and read using --from-
236 dump are formatted as follows:
237 · The SMBIOS or DMI entry point is located at offset 0x00. It is
239 crafted to hard-code the table address at offset 0x20.
240 · The DMI table is located at offset 0x20.
242
245 /dev/mem /sys/firmware/dmi/tables/smbios_entry_point (Linux only)
246 /sys/firmware/dmi/tables/DMI (Linux only)
247
249 More often than not, information contained in the DMI tables is inaccu‐
250 rate, incomplete or simply wrong.
251
253 Alan Cox, Jean Delvare
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256 biosdecode(8), mem(4), ownership(8), vpddecode(8)
257dmidecode March 2012 DMIDECODE(8)