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Commit ca01d6dd authored by Tony Luck's avatar Tony Luck
Browse files

pstore: new filesystem interface to platform persistent storage 



Some platforms have a small amount of non-volatile storage that
can be used to store information useful to diagnose the cause of
a system crash.  This is the generic part of a file system interface
that presents information from the crash as a series of files in
/dev/pstore.  Once the information has been seen, the underlying
storage is freed by deleting the files.

Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 90a8a73c

Documentation/ABI/testing/pstore

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Where:		/dev/pstore/...

Date:		January 2011

Kernel Version: 2.6.38

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 - /dev/pstore



		$ ls -l /dev/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 /dev/pstore/dmesg-erst-1



		The expectation is that all files in /dev/pstore

		will be saved elsewhere and erased from persistent store

		soon after boot to free up space ready for the next

		catastrophe.

Documentation/ABI/testing/sysfs-fs-pstore

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What:		/sys/fs/pstore/kmsg_bytes

Date:		January 2011

Kernel Version: 2.6.38

Contact:	"Tony Luck" <tony.luck@intel.com>

Description:

		Controls amount of console log that will be saved

		to persistent store on oops/panic.

fs/Kconfig

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@@ -188,6 +188,7 @@ source "fs/omfs/Kconfig" 
source "fs/hpfs/Kconfig"

source "fs/qnx4/Kconfig"

source "fs/romfs/Kconfig"

source "fs/pstore/Kconfig"

source "fs/sysv/Kconfig"

source "fs/ufs/Kconfig"

source "fs/exofs/Kconfig"

fs/Makefile

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@@ -121,3 +121,4 @@ obj-$(CONFIG_BTRFS_FS) += btrfs/ 
obj-$(CONFIG_GFS2_FS)           += gfs2/

obj-$(CONFIG_EXOFS_FS)          += exofs/

obj-$(CONFIG_CEPH_FS)		+= ceph/

obj-$(CONFIG_PSTORE)		+= pstore/

fs/pstore/Kconfig

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config PSTORE

	bool "Persistant store support"

	default n

	help

	   This option enables generic access to platform level

	   persistent storage via "pstore" filesystem that can

	   be mounted as /dev/pstore.  Only useful if you have

	   a platform level driver that registers with pstore to

	   provide the data, so you probably should just go say "Y"

	   (or "M") to a platform specific persistent store driver

	   (e.g. ACPI_APEI on X86) which will select this for you.

	   If you don't have a platform persistent store driver,

	   say N.