| What: /sys/fs/pstore/... (or /dev/pstore/...) |
| Date: March 2011 |
| KernelVersion: 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. |
