| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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 | |