What: /sys/firmware/opal/elog
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Date: Feb 2014
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Contact: Stewart Smith <stewart@linux.vnet.ibm.com>
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Description:
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This directory exposes error log entries retrieved
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through the OPAL firmware interface.
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Each error log is identified by a unique ID and will
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exist until explicitly acknowledged to firmware.
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Each log entry has a directory in /sys/firmware/opal/elog.
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Log entries may be purged by the service processor
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before retrieved by firmware or retrieved/acknowledged by
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Linux if there is no room for more log entries.
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In the event that Linux has retrieved the log entries
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but not explicitly acknowledged them to firmware and
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the service processor needs more room for log entries,
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the only remaining copy of a log message may be in
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Linux.
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Typically, a user space daemon will monitor for new
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entries, read them out and acknowledge them.
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The service processor may be able to store more log
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entries than firmware can, so after you acknowledge
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an event from Linux you may instantly get another one
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from the queue that was generated some time in the past.
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The raw log format is a binary format. We currently
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do not parse this at all in kernel, leaving it up to
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user space to solve the problem. In future, we may
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do more parsing in kernel and add more files to make
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it easier for simple user space processes to extract
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more information.
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For each log entry (directory), there are the following
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files:
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id: An ASCII representation of the ID of the
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error log, in hex - e.g. "0x01".
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type: An ASCII representation of the type id and
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description of the type of error log.
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Currently just "0x00 PEL" - platform error log.
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In the future there may be additional types.
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raw: A read-only binary file that can be read
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to get the raw log entry. These are
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<16kb, often just hundreds of bytes and
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"average" 2kb.
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acknowledge: Writing 'ack' to this file will acknowledge
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the error log to firmware (and in turn
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the service processor, if applicable).
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Shortly after acknowledging it, the log
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entry will be removed from sysfs.
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Reading this file will list the supported
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operations (currently just acknowledge).
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