1What: /sys/fs/pstore/... 2What: /dev/pstore/... 3Date: March 2011 4KernelVersion: 2.6.39 5Contact: tony.luck@intel.com 6Description: Generic interface to platform dependent persistent storage. 7 8 Platforms that provide a mechanism to preserve some data 9 across system reboots can register with this driver to 10 provide a generic interface to show records captured in 11 the dying moments. In the case of a panic the last part 12 of the console log is captured, but other interesting 13 data can also be saved:: 14 15 # mount -t pstore -o kmsg_bytes=8000 - /sys/fs/pstore 16 17 $ ls -l /sys/fs/pstore/ 18 total 0 19 -r--r--r-- 1 root root 7896 Nov 30 15:38 dmesg-erst-1 20 21 Different users of this interface will result in different 22 filename prefixes. Currently two are defined: 23 24 - "dmesg" - saved console log 25 - "mce" - architecture dependent data from fatal h/w error 26 27 Once the information in a file has been read, removing 28 the file will signal to the underlying persistent storage 29 device that it can reclaim the space for later re-use:: 30 31 $ rm /sys/fs/pstore/dmesg-erst-1 32 33 The expectation is that all files in /sys/fs/pstore/ 34 will be saved elsewhere and erased from persistent store 35 soon after boot to free up space ready for the next 36 catastrophe. 37 38 The 'kmsg_bytes' mount option changes the target amount of 39 data saved on each oops/panic. Pstore saves (possibly 40 multiple) files based on the record size of the underlying 41 persistent storage until at least this amount is reached. 42 Default is 10 Kbytes. 43 44 Pstore only supports one backend at a time. If multiple 45 backends are available, the preferred backend may be 46 set by passing the pstore.backend= argument to the kernel at 47 boot time. 48