1Where: /sys/fs/pstore/... (or /dev/pstore/...) 2Date: March 2011 3Kernel Version: 2.6.39 4Contact: tony.luck@intel.com 5Description: 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 48