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