1What:		/sys/firmware/opal/elog
2Date:		Feb 2014
3Contact:	Stewart Smith <stewart@linux.vnet.ibm.com>
4Description:
5		This directory exposes error log entries retrieved
6		through the OPAL firmware interface.
7
8		Each error log is identified by a unique ID and will
9		exist until explicitly acknowledged to firmware.
10
11		Each log entry has a directory in /sys/firmware/opal/elog.
12
13		Log entries may be purged by the service processor
14		before retrieved by firmware or retrieved/acknowledged by
15		Linux if there is no room for more log entries.
16
17		In the event that Linux has retrieved the log entries
18		but not explicitly acknowledged them to firmware and
19		the service processor needs more room for log entries,
20		the only remaining copy of a log message may be in
21		Linux.
22
23		Typically, a user space daemon will monitor for new
24		entries, read them out and acknowledge them.
25
26		The service processor may be able to store more log
27		entries than firmware can, so after you acknowledge
28		an event from Linux you may instantly get another one
29		from the queue that was generated some time in the past.
30
31		The raw log format is a binary format. We currently
32		do not parse this at all in kernel, leaving it up to
33		user space to solve the problem. In future, we may
34		do more parsing in kernel and add more files to make
35		it easier for simple user space processes to extract
36		more information.
37
38		For each log entry (directory), there are the following
39		files:
40
41		id:		An ASCII representation of the ID of the
42				error log, in hex - e.g. "0x01".
43
44		type:		An ASCII representation of the type id and
45				description of the type of error log.
46				Currently just "0x00 PEL" - platform error log.
47				In the future there may be additional types.
48
49		raw:		A read-only binary file that can be read
50				to get the raw log entry. These are
51				<16kb, often just hundreds of bytes and
52				"average" 2kb.
53
54		acknowledge:	Writing 'ack' to this file will acknowledge
55				the error log to firmware (and in turn
56				the service processor, if applicable).
57				Shortly after acknowledging it, the log
58				entry will be removed from sysfs.
59				Reading this file will list the supported
60				operations (curently just acknowledge).