|To:||Linux Kernel Mailing List <email@example.com>|
|Subject:||[RFC Patch 0/6] slimdump: Enable slimdump if crashing kernel memory is not required|
|Date:||Thu, 26 May 2011 22:37:22 +0530|
|Cc:||Andi Kleen <firstname.lastname@example.org>, "Luck, Tony" <email@example.com>, Vivek Goyal <firstname.lastname@example.org>, email@example.com, "Eric W. Biederman" <firstname.lastname@example.org>, email@example.com|
Hi All, Please find a patchset that implements 'slimdump' - a new type of coredump (captured through kdump) which will retain only essential debugging information but will discard old kernel memory (which is mostly irrelevant) in case of system crashes triggered through fatal hardware errors. When a system crashes due to an unrecoverable memory error, kdump would ordinarily attempt to read/capture the crashing kernel's memory which has the following undesirable consequences: - The old kernel memory is irrelevant for debugging crashes initiated due to hardware errors (such as physical memory corruption causing fatal machine check exceptions - MCE). - The kdump capture kernel might experience a second MCE when attempting to read the corrupt memory area having fatal results (and failure to capture the coredump). 'slimdump' is particularly useful in avoiding the above hazards. It is a light-weight dump and increases the reliability of the system by avoiding unsafe operations. In essence slimdump enables light-weight coredumps and increases the reliability of the system by avoiding unsafe operations. Summary of the patches ---- Patch 1, 2 - Patches from Andi Kleen's tree git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6.git which introduce an enhanced panic function - xpanic(). Patch 3 - Introduces a new PANIC_MCE flag to signal the need for SlimDump for MCE initiated panic calls. Patch 4 - Append a new elf-note inside coredump containing MCE related registers Patch 5 - Create a SlimDump by discarding old kernel's memory Patch 6 - Patch for 'crash' tool (http://people.redhat.com/anderson/crash-5.1.5.tar.gz) to recognise the new elf-notes section. The patches have been tested from inside a VM and have been found to work fine. The user-space tool used for copying the coredump is 'cp' (makedumpfile testing will be done soon). Example -------- Normal vmcore ----------- # ls -lh /home/prasadkr/vmcore.usual -r-------- 1 root root 1.6G May 17 01:07 /home/prasadkr/vmcore.usual slimdump ----------- # ls -lh /home/prasadkr/vmcore.SlimDump -r-------- 1 root root 1.8K May 18 23:28 /home/prasadkr/vmcore.SlimDump # ./crash vmlinux vmcore.SlimDump crash 5.1.5 Copyright (C) 2002-2011 Red Hat, Inc. Copyright (C) 2004, 2005, 2006 IBM Corporation Copyright (C) 1999-2006 Hewlett-Packard Co Copyright (C) 2005, 2006 Fujitsu Limited Copyright (C) 2006, 2007 VA Linux Systems Japan K.K. Copyright (C) 2005 NEC Corporation Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc. Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc. This program is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Enter "help copying" to see the conditions. This program has absolutely no warranty. Enter "help warranty" for details. "System crashed due to a hardware memory error. No coredump available." # # Thanks, K.Prasad _______________________________________________________ ltcras mailing list firstname.lastname@example.org To unsubscribe from the list, change your list options or if you have forgotten your list password visit: http://lists.linux.ibm.com/mailman/listinfo/ltcras
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