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 (currently just acknowledge). 61