core_collector doc basic fix
Update core_collector in kdump.conf[.5]: 1. accept <command> not limited to makedumpfile 2. add notes about default core_collector 3. add notes about flattened vmcore Signed-off-by: Dave Young <dyoung@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
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Dave Young
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26
kdump.conf
26
kdump.conf
@ -34,14 +34,22 @@
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# dumping to. Ignored for raw device dumps.
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# If unset, will default to /var/crash.
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#
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# core_collector makedumpfile <options>
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# - This directive allows you to use the dump filtering
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# program makedumpfile to retrieve your core, which on
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# some arches can drastically reduce core file size.
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# See /sbin/makedumpfile --help for a list of options.
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# Note that the -i and -g options are not needed here,
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# as the initrd will automatically be populated with
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# a config file appropriate for the running kernel.
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# core_collector <command> <options>
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# - This allows you to specify the command to copy
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# the vmcore. You could use the dump filtering
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# program makedumpfile, the default one, to retrieve
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# your core, which on some arches can drastically
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# reduce core file size. See /sbin/makedumpfile --help
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# for a list of options. Note that the -i and -g
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# options are not needed here, as the initrd will
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# automatically be populated with a config file
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# appropriate for the running kernel.
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# Default core_collector for raw dump is:
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# "makedumpfile -F -c --message-level 1 -d 31".
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# Default core_collector for other targets is:
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# "makedumpfile -c --message-level 1 -d 31".
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# For core_collector format details please refer to
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# kexec-kdump-howto.txt or kdump.conf manpage.
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#
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# extra_bins <binaries | shell scripts>
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# - This directive allows you to specify additional
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@ -82,7 +90,7 @@
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#net user@my.server.com
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#sshkey /root/.ssh/kdump_id_rsa
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path /var/crash
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#core_collector makedumpfile -c
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#core_collector makedumpfile -c --message-level 1 -d 31
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#extra_bins /usr/bin/lftp
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#extra_modules gfs2
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#default shell
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74
kdump.conf.5
74
kdump.conf.5
@ -61,14 +61,32 @@ Append path to the filesystem device which you are dumping to.
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Ignored for raw device dumps. If unset, will default to /var/crash.
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.RE
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.B core_collector makedumpfile <options>
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.B core_collector <command> <options>
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.RS
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This directive allows you to use the dump filtering program
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makedumpfile to retrieve your core, which on some arches can
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drastically reduce core file size. See /sbin/makedumpfile --help for
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a list of options. Note that the -i and -g options are not needed
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here, as the initrd will automatically be populated with a config file
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appropriate for the running kernel.
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This allows you to specify the command to copy the vmcore.
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You could use the dump filtering program makedumpfile, the default one,
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to retrieve your core, which on some arches can drastically reduce
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core file size. See /sbin/makedumpfile --help for a list of options.
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Note that the -i and -g options are not needed here, as the initrd
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will automatically be populated with a config file appropriate
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for the running kernel.
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.PP
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Note 1: About default core collector:
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Default core_collector for raw dump is:
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"makedumpfile -F -c --message-level 1 -d 31".
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Default core_collector for other targets is:
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"makedumpfile -c --message-level 1 -d 31".
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Even if core_collector option is commented out in kdump.conf, makedumpfile
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is default core collector and kdump uses it internally.
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If one does not want makedumpfile as default core_collector, then they
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need to specify one using core_collector option to change the behavior.
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.PP
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Note 2: If "makedumpfile -F" is used then you will get a flattened format
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vmcore.flat, you will need to use "makedumpfile -R" to rearrange the
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dump data from stdard input to a normal dumpfile (readable with analysis
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tools).
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ie. "makedumpfile -R vmcore < vmcore.flat"
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.RE
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.B extra_bins <binaries | shell scripts>
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@ -103,8 +121,48 @@ Note: kdump uses bash as the default shell.
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.RE
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.SH EXAMPLES
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Here is some examples for core_collector option:
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.PP
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Core collector command format depends on dump target type. Typically for
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filesystem (local/remote), core_collector should accept two arguments.
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First one is source file and second one is target file. For ex.
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.TP
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ex1.
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core_collector "cp --sparse=always"
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see
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Above will effectively be translated to:
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cp --sparse=always /proc/vmcore <dest-path>/vmcore
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.TP
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ex2.
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core_collector "makedumpfile -c --message-level 1 -d 31"
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Above will effectively be translated to:
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makedumpfile -c --message-level 1 -d 31 /proc/vmcore <dest-path>/vmcore
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.PP
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For dump targets like raw, in general, core collector should expect
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one argument (source file) and should output the processed core on standard
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output. This standard output will be saved to destination using appropriate
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commands.
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raw dumps examples:
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.TP
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ex3.
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core_collector "cat"
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Above will effectively be translated to.
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cat /proc/vmcore | dd of=<target-device>
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.TP
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ex4.
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core_collector "makedumpfile -F -c --message-level 1 -d 31"
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Above will effectively be translated to.
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makedumpfile -F -c --message-level 1 -d 31 | dd of=<target-device>
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.PP
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examples for other options please see
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.I /etc/kdump.conf
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.SH SEE ALSO
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@ -440,18 +440,74 @@ is a dump filtering and compression utility provided with kexec-tools. On
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some architectures, it can drastically reduce the size of your vmcore files,
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which becomes very useful on systems with large amounts of memory.
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A typical setup is 'core_collector makedumpfile -c', but check the output of
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'/sbin/makedumpfile --help' for a list of all available options (-i and -g
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don't need to be specified, they're automatically taken care of). Note that
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use of makedumpfile requires that the kernel-debuginfo package corresponding
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with your running kernel be installed.
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A typical setup is 'core_collector makedumpfile -F -c --message-level 1 -d 31',
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but check the output of '/sbin/makedumpfile --help' for a list of all available
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options (-i and -g don't need to be specified, they're automatically taken care
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of). Note that use of makedumpfile requires that the kernel-debuginfo package
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corresponding with your running kernel be installed.
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Also note that makedumpfile is only used from the initramfs. Saving a
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core from the initscript in the root filesystem is considered a last ditch
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effort, only used when the initramfs has failed to save the core properly.
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As such only the cp utiltiy is used in the initscripts. The implication
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here is that in order to use makedumpfile as your core collector, you must
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specify a dump target in /etc/kdump.conf.
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Core collector command format depends on dump target type. Typically for
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filesystem (local/remote), core_collector should accept two arguments.
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First one is source file and second one is target file. For ex.
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ex1.
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---
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core_collector "cp --sparse=always"
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Above will effectively be translated to:
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cp --sparse=always /proc/vmcore <dest-path>/vmcore
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ex2.
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---
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core_collector "makedumpfile -c --message-level 1 -d 31"
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Above will effectively be translated to:
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makedumpfile -c --message-level 1 -d 31 /proc/vmcore <dest-path>/vmcore
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For dump targets like raw, in general, core collector should expect
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one argument (source file) and should output the processed core on standard
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output. This standard output will be saved to destination using appropriate
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commands.
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raw dumps core_collector examples:
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---------
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ex3.
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---
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core_collector "cat"
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Above will effectively be translated to.
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cat /proc/vmcore | dd of=<target-device>
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ex4.
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---
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core_collector "makedumpfile -F -c --message-level 1 -d 31"
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Above will effectively be translated to.
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makedumpfile -F -c --message-level 1 -d 31 | dd of=<target-device>
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About default core collector
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----------------------------
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Default core_collector for ssh/raw dump is:
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"makedumpfile -F -c --message-level 1 -d 31".
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Default core_collector for other targets is:
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"makedumpfile -c --message-level 1 -d 31".
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Even if core_collector option is commented out in kdump.conf, makedumpfile
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is default core collector and kdump uses it internally.
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If one does not want makedumpfile as default core_collector, then they
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need to specify one using core_collector option to change the behavior.
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Note: If "makedumpfile -F" is used then you will get a flattened format
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vmcore.flat, you will need to use "makedumpfile -R" to rearrange the
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dump data from stdard input to a normal dumpfile (readable with analysis
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tools).
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For example: "makedumpfile -R vmcore < vmcore.flat"
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Caveats:
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