1 What: /sys/firmware/dmi/entries/
2 Date: February 2011
3 Contact: Mike Waychison <mikew@google.co
4 Description:
5 Many machines' firmware (x86 a
6 SMBIOS tables to the operating
7 information is often valuable
8 cases where there are OEM exte
9
10 The kernel itself does not rel
11 information in these tables be
12 cannot ensure that the data as
13 without error either.
14
15 DMI is structured as a large t
16 each entry has a common header
17 length of the entry, as well a
18 'handle' that is supposed to b
19 entries.
20
21 Some entries are required by t
22 others are optional. In gener
23 never expect to find a specifi
24 system unless they know for ce
25 is doing. Machine to machine
26
27 Multiple entries of the same t
28 to handle these duplicate entr
29 assigned by the operating syst
30 derived from an entry type's o
31 to say, if there are 'N' multi
32 'T' in the DMI tables (adjacen
33 doesn't matter), they will be
34 entries "T-0" through "T-(N-1)
35
36 Example entry directories::
37
38 /sys/firmware/dmi/entr
39 /sys/firmware/dmi/entr
40 /sys/firmware/dmi/entr
41 /sys/firmware/dmi/entr
42 ...
43
44 Instance numbers are used in l
45 assigned entry handles as the
46 guarantees that handles as exp
47 there are likely firmware imag
48 the wild.
49
50 Each DMI entry in sysfs has th
51 exported as attributes:
52
53 ======== ====================
54 handle The 16bit 'handle' t
55 entry by the firmwar
56 referred to by other
57 length The length of the en
58 entry itself. Note
59 total count of bytes
60 entry. This value r
61 the "formatted" port
62 "formatted" region i
63 the "unformatted" re
64 terminated strings,
65 by a two nul charact
66 raw The raw bytes of the
67 "formatted" portion
68 "unformatted" string
69 and the two terminat
70 type The type of the entr
71 as found in the dire
72 how the rest of the
73 instance The instance ordinal
74 given type. This va
75 in the parent direct
76 position The ordinal position
77 within the entirety
78 ======== ====================
79
80 **Entry Specialization**
81
82 Some entry types may have othe
83 sysfs. Not all types are spec
84
85 **Type 15 - System Event Log**
86
87 This entry allows the firmware
88 events the system has taken.
89 typically backed by nvram, but
90 details are abstracted by this
91 is exported in the directory::
92
93 /sys/firmware/dmi/entries/15
94
95 and has the following attribut
96 SMBIOS / DMI specification und
97
98 - area_length
99 - header_start_offset
100 - data_start_offset
101 - access_method
102 - status
103 - change_token
104 - access_method_address
105 - header_format
106 - per_log_type_descriptor_leng
107 - type_descriptors_supported_c
108
109 As well, the kernel exports th
110
111 ============= ============
112 raw_event_log The raw bina
113 as described
114 ============= ============
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