0001 What: /sys/fs/pstore/...
0002 What: /dev/pstore/...
0003 Date: March 2011
0004 KernelVersion: 2.6.39
0005 Contact: tony.luck@intel.com
0006 Description: Generic interface to platform dependent persistent storage.
0007
0008 Platforms that provide a mechanism to preserve some data
0009 across system reboots can register with this driver to
0010 provide a generic interface to show records captured in
0011 the dying moments. In the case of a panic the last part
0012 of the console log is captured, but other interesting
0013 data can also be saved::
0014
0015 # mount -t pstore -o kmsg_bytes=8000 - /sys/fs/pstore
0016
0017 $ ls -l /sys/fs/pstore/
0018 total 0
0019 -r--r--r-- 1 root root 7896 Nov 30 15:38 dmesg-erst-1
0020
0021 Different users of this interface will result in different
0022 filename prefixes. Currently two are defined:
0023
0024 - "dmesg" - saved console log
0025 - "mce" - architecture dependent data from fatal h/w error
0026
0027 Once the information in a file has been read, removing
0028 the file will signal to the underlying persistent storage
0029 device that it can reclaim the space for later re-use::
0030
0031 $ rm /sys/fs/pstore/dmesg-erst-1
0032
0033 The expectation is that all files in /sys/fs/pstore/
0034 will be saved elsewhere and erased from persistent store
0035 soon after boot to free up space ready for the next
0036 catastrophe.
0037
0038 The 'kmsg_bytes' mount option changes the target amount of
0039 data saved on each oops/panic. Pstore saves (possibly
0040 multiple) files based on the record size of the underlying
0041 persistent storage until at least this amount is reached.
0042 Default is 10 Kbytes.
0043
0044 Pstore only supports one backend at a time. If multiple
0045 backends are available, the preferred backend may be
0046 set by passing the pstore.backend= argument to the kernel at
0047 boot time.
