Documentation/ABI/testing/pstore

   1 Where:          /sys/fs/pstore/... (or /dev/pstore/...)
   2 Date:           March 2011
   3 Kernel Version: 2.6.39
   4 Contact:        tony.luck@intel.com
   5 Description:    Generic interface to platform dependent persistent storage.
   6
   7                 Platforms that provide a mechanism to preserve some data
   8                 across system reboots can register with this driver to
   9                 provide a generic interface to show records captured in
  10                 the dying moments.  In the case of a panic the last part
  11                 of the console log is captured, but other interesting
  12                 data can also be saved.
  13
  14                 # mount -t pstore -o kmsg_bytes=8000 - /sys/fs/pstore
  15
  16                 $ ls -l /sys/fs/pstore/
  17                 total 0
  18                 -r--r--r-- 1 root root 7896 Nov 30 15:38 dmesg-erst-1
  19
  20                 Different users of this interface will result in different
  21                 filename prefixes.  Currently two are defined:
  22
  23                 "dmesg" - saved console log
  24                 "mce"   - architecture dependent data from fatal h/w error
  25
  26                 Once the information in a file has been read, removing
  27                 the file will signal to the underlying persistent storage
  28                 device that it can reclaim the space for later re-use.
  29
  30                 $ rm /sys/fs/pstore/dmesg-erst-1
  31
  32                 The expectation is that all files in /sys/fs/pstore/
  33                 will be saved elsewhere and erased from persistent store
  34                 soon after boot to free up space ready for the next
  35                 catastrophe.
  36
  37                 The 'kmsg_bytes' mount option changes the target amount of
  38                 data saved on each oops/panic. Pstore saves (possibly
  39                 multiple) files based on the record size of the underlying
  40                 persistent storage until at least this amount is reached.
  41                 Default is 10 Kbytes.
  42
  43                 Pstore only supports one backend at a time. If multiple
  44                 backends are available, the preferred backend may be
  45                 set by passing the pstore.backend= argument to the kernel at
  46                 boot time.
  47