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    Subject[RFC Patch 0/6] slimdump: Enable slimdump if crashing kernel memory is not required
    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:// 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

    Patch 5 - Create a SlimDump by discarding old kernel's memory

    Patch 6 - Patch for 'crash' tool
    ( to recognise the
    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).

    Normal vmcore
    # ls -lh /home/prasadkr/vmcore.usual
    -r-------- 1 root root 1.6G May 17 01:07 /home/prasadkr/vmcore.usual

    # 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
    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

    "System crashed due to a hardware memory error. No coredump available."

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