1 What:		/sys/firmware/opal/elog
2 Date:		Feb 2014
3 Contact:	Stewart Smith <stewart@linux.vnet.ibm.com>
4 Description:
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 		==============  ================================================
42 		id:		An ASCII representation of the ID of the
43 				error log, in hex - e.g. "0x01".
44 
45 		type:		An ASCII representation of the type id and
46 				description of the type of error log.
47 				Currently just "0x00 PEL" - platform error log.
48 				In the future there may be additional types.
49 
50 		raw:		A read-only binary file that can be read
51 				to get the raw log entry. These are
52 				<16kb, often just hundreds of bytes and
53 				"average" 2kb.
54 
55 		acknowledge:	Writing 'ack' to this file will acknowledge
56 				the error log to firmware (and in turn
57 				the service processor, if applicable).
58 				Shortly after acknowledging it, the log
59 				entry will be removed from sysfs.
60 				Reading this file will list the supported
61 				operations (currently just acknowledge).
62 		==============  ================================================
63