v4.19.13 snapshot.
diff --git a/Documentation/ABI/testing/pstore b/Documentation/ABI/testing/pstore
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+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.
+