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Diffstat (limited to 'Documentation/ABI/testing/sysfs-firmware-dmi')
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diff --git a/Documentation/ABI/testing/sysfs-firmware-dmi b/Documentation/ABI/testing/sysfs-firmware-dmi deleted file mode 100644 index c78f9ab01e56..000000000000 --- a/Documentation/ABI/testing/sysfs-firmware-dmi +++ /dev/null @@ -1,110 +0,0 @@ -What: /sys/firmware/dmi/ -Date: February 2011 -Contact: Mike Waychison <mikew@google.com> -Description: - Many machines' firmware (x86 and ia64) export DMI / - SMBIOS tables to the operating system. Getting at this - information is often valuable to userland, especially in - cases where there are OEM extensions used. - - The kernel itself does not rely on the majority of the - information in these tables being correct. It equally - cannot ensure that the data as exported to userland is - without error either. - - DMI is structured as a large table of entries, where - each entry has a common header indicating the type and - length of the entry, as well as a firmware-provided - 'handle' that is supposed to be unique amongst all - entries. - - Some entries are required by the specification, but many - others are optional. In general though, users should - never expect to find a specific entry type on their - system unless they know for certain what their firmware - is doing. Machine to machine experiences will vary. - - Multiple entries of the same type are allowed. In order - to handle these duplicate entry types, each entry is - assigned by the operating system an 'instance', which is - derived from an entry type's ordinal position. That is - to say, if there are 'N' multiple entries with the same type - 'T' in the DMI tables (adjacent or spread apart, it - doesn't matter), they will be represented in sysfs as - entries "T-0" through "T-(N-1)": - - Example entry directories: - - /sys/firmware/dmi/entries/17-0 - /sys/firmware/dmi/entries/17-1 - /sys/firmware/dmi/entries/17-2 - /sys/firmware/dmi/entries/17-3 - ... - - Instance numbers are used in lieu of the firmware - assigned entry handles as the kernel itself makes no - guarantees that handles as exported are unique, and - there are likely firmware images that get this wrong in - the wild. - - Each DMI entry in sysfs has the common header values - exported as attributes: - - handle : The 16bit 'handle' that is assigned to this - entry by the firmware. This handle may be - referred to by other entries. - length : The length of the entry, as presented in the - entry itself. Note that this is _not the - total count of bytes associated with the - entry_. This value represents the length of - the "formatted" portion of the entry. This - "formatted" region is sometimes followed by - the "unformatted" region composed of nul - terminated strings, with termination signalled - by a two nul characters in series. - raw : The raw bytes of the entry. This includes the - "formatted" portion of the entry, the - "unformatted" strings portion of the entry, - and the two terminating nul characters. - type : The type of the entry. This value is the same - as found in the directory name. It indicates - how the rest of the entry should be interpreted. - instance: The instance ordinal of the entry for the - given type. This value is the same as found - in the parent directory name. - position: The ordinal position (zero-based) of the entry - within the entirety of the DMI entry table. - - === Entry Specialization === - - Some entry types may have other information available in - sysfs. Not all types are specialized. - - --- Type 15 - System Event Log --- - - This entry allows the firmware to export a log of - events the system has taken. This information is - typically backed by nvram, but the implementation - details are abstracted by this table. This entry's data - is exported in the directory: - - /sys/firmware/dmi/entries/15-0/system_event_log - - and has the following attributes (documented in the - SMBIOS / DMI specification under "System Event Log (Type 15)": - - area_length - header_start_offset - data_start_offset - access_method - status - change_token - access_method_address - header_format - per_log_type_descriptor_length - type_descriptors_supported_count - - As well, the kernel exports the binary attribute: - - raw_event_log : The raw binary bits of the event log - as described by the DMI entry. |