What: /sys/fs/pstore/... (or /dev/pstore/...)
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Date: March 2011
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KernelVersion: 2.6.39
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Contact: tony.luck@intel.com
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Description: Generic interface to platform dependent persistent storage.
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Platforms that provide a mechanism to preserve some data
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across system reboots can register with this driver to
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provide a generic interface to show records captured in
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the dying moments. In the case of a panic the last part
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of the console log is captured, but other interesting
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data can also be saved::
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# mount -t pstore -o kmsg_bytes=8000 - /sys/fs/pstore
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$ ls -l /sys/fs/pstore/
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total 0
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-r--r--r-- 1 root root 7896 Nov 30 15:38 dmesg-erst-1
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Different users of this interface will result in different
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filename prefixes. Currently two are defined:
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- "dmesg" - saved console log
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- "mce" - architecture dependent data from fatal h/w error
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Once the information in a file has been read, removing
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the file will signal to the underlying persistent storage
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device that it can reclaim the space for later re-use::
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$ rm /sys/fs/pstore/dmesg-erst-1
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The expectation is that all files in /sys/fs/pstore/
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will be saved elsewhere and erased from persistent store
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soon after boot to free up space ready for the next
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catastrophe.
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The 'kmsg_bytes' mount option changes the target amount of
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data saved on each oops/panic. Pstore saves (possibly
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multiple) files based on the record size of the underlying
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persistent storage until at least this amount is reached.
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Default is 10 Kbytes.
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Pstore only supports one backend at a time. If multiple
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backends are available, the preferred backend may be
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set by passing the pstore.backend= argument to the kernel at
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boot time.
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