crash extension modules

The echo.c extension module can be used as a simple template for creating an extension module to implement a new command.

Crash extension modules are required to #include the defs.h file from the top-level directory of crash source tree. There are three suggested manners for building a module:

  1. Hand-compile the module's .so shared object file like this:

      $ gcc -shared -rdynamic -o <module>.so <module>.c -fPIC -D<machine-type> $(TARGET_CFLAGS)

    where <machine-type> is X86, X86_64, IA64, PPC64, ARM, S390 or S390X, and where $(TARGET_CFLAGS) is -D_FILE_OFFSET_BITS=64 on 32-bit architectures, and -m64 on ppc64.

    If the extension module contains the obsolete _init() and _fini() functions, then the -nostartfiles compiler option is also required. However it is recommended that constructor and destructor functions be used as recommended by the dlopen(3) man page.

    As a convenience, the crash utility's crash-<version>.src.rpm package builds a crash-devel sub-package, which installs defs.h into /usr/include/crash/defs.h.

  2. Alternatively, copy the module's .c source file to the crash-<version>/extensions subdirectory. Then, from the top-level crash-<version> directory, enter:

      $ make extensions

    If the default compile line does not suffice, create an accompanying .mk makefile with the same prefix as the .c file, copy it to the crash-<version>/extensions subdirectory, and enter the same make extensions command as above.

  3. Lastly, some extension modules that do have both <module>.c and <module>.mk files may be built without the crash source tree if the defs.h file is located in the current directory or in the /usr/include/crash directory:

      $ make -f <module>.mk

To add the module's command(s) to a running crash session, enter:

  crash> extend <path-to>/<module>.so

The command(s) registered by the extension module will appear in the crash help menu. The module can be installed automatically if the extend command above is entered in either ./.crashrc or $HOME/.crashrc.

If the crash-<version>.src.rpm file is used to build the crash package, a crash-extensions-<version>.rpm subpackage containing a subset of the extension modules below is built. If the subpackage is installed, the extension modules will be located in /usr/lib/crash/extensions or /usr/lib64/crash/extensions, whichever is appropriate.

Lastly, there is a crash -x command line option that will load extension modules automatically from a particular directory. The search for the extension module directory will be done in the following order, and the first one (if any) that exists will be selected as the target directory:

  1. the directory specified in the CRASH_EXTENSIONS shell environment variable
  2. /usr/lib64/crash/extensions (64-bit architectures)
  3. /usr/lib/crash/extensions
  4. ./extensions
All extension modules that are found in the target directory will be loaded automatically.

module commands   comments
echo.c echo
  • Provided primarily as a template for writing new extension modules.

  • To build the module from the top-level crash-<version> directory, enter:
      $ make extensions

  • This module's source file is contained within the crash-<version>.src.rpm and crash-<version>.tar.gz files, and the compiled module is included in the crash-extensions-<version>.rpm subpackage when crash-<version>.src.rpm is used to build the crash package.

  • Author: Dave Anderson  <anderson@redhat.com>
snap.c
snap.mk
snap
  • Takes a snapshot of physical memory and creates an ELF vmcore. The default vmcore is a kdump-style dumpfile, but a netdump-style may be optionally created. It supports the X86, X86_64, IA64 and PPC64 architectures only. All caveats regarding the taking of a "live" memory snapshot apply, such as the constantly-changing state of the kernel's slab subsystem or active process set while the dump is taking place.

  • To build the module from the top-level crash-<version> directory, enter:
      $ make extensions

  • The module also serves as an example of an extension module that can be built in all three manners:

    1. Copy snap.c to the crash-<version>/extensions subdirectory, and from the top-level crash-<version> directory, enter:
        $ make extensions
    2. Copy both snap.c and snap.mk to the crash-<version>/extensions subdirectory, and from the top-level crash-<version> directory, enter:
        $ make extensions
    3. Copy snap.c, snap.mk, and defs.h into any directory. The defs.h file may also be located in the /usr/include/crash directory, as would be the case if the crash-devel sub-package had been installed. Then enter:
        $ make -f snap.mk

  • This module's source file and makefile are contained within the crash-<version>.src.rpm and crash-<version>.tar.gz files, and the compiled module is included in the crash-extensions-<version>.rpm subpackage when crash-<version>.src.rpm is used to build the crash package.

  • Author: Dave Anderson  <anderson@redhat.com>
eppic.c
eppic.mk
load
unload
edit
sclass
sdebug
sname
  • This module is a prerequisite for the loading of EPPIC (Embeddable Pre-Processor and Interpreter for C) scripts.

  • To build the module from the top-level crash-<version> directory, enter:
      $ make extensions

  • Upon installing the eppic.so object file with extend, any EPPIC scripts located in the /usr/share/eppic/crash or $HOME/.eppic directories will be loaded automatically.

  • This module's source files are downloaded automatically from their git tree located at http://code.google.com/p/eppic, and the compiled extension module is included in the crash-extensions-<version>.rpm subpackage when crash-<version>.src.rpm is used to build the crash package.

  • Author: Luc Chouinard  <lchouinard@s2sys.com>
dminfo.c dminfo
  • Device Mapper information.

  • To build the module from the top-level crash-<version> directory, enter:
      $ make extensions

  • This module's source file is contained within the crash-<version>.src.rpm and crash-<version>.tar.gz files, and the compiled module is included in the crash-extensions-<version>.rpm subpackage when crash-<version>.src.rpm is used to build the crash package.

  • Author: NEC Japan
trace.c trace
  • Displays kernel tracing data and traced events that occurred prior to a panic.

  • To build the module from the top-level crash-<version> directory, enter:
      $ make extensions

  • This module's source file is contained within the crash-<version>.src.rpm and crash-<version>.tar.gz files, and the compiled module is included in the crash-extensions-<version>.rpm subpackage when crash-<version>.src.rpm is used to build the crash package.

  • Author: Lai Jiangshan  <laijs@cn.fujitsu.com>

  • Maintainer: Qiao Nuohan  <qiaonuohan@cn.fujitsu.com>
gcore.c

crash-gcore-command-1.2.2.tar.gz
gcore
  • Create a core dump file of a user-space task that was running in a kernel dumpfile. The module supports the X86, X86_64 and ARM architectures.

  • If /usr/include/crash/defs.h exists, the module may be built like so:
      $ tar xzf crash-gcore-command-1.2.2.tar.gz
      $ cd crash-gcore-command-1.2.2
      $ make -f gcore.mk

  • Alternatively, defs.h may be copied to the current directory:
      $ tar xzf crash-gcore-command-1.2.2.tar.gz
      $ cd crash-gcore-command-1.2.2
      $ cp <path-to>/defs.h .
      $ make -f gcore.mk

  • To build the module from the top-level crash-<version> directory, enter:
      $ tar xzf crash-gcore-command-1.2.2.tar.gz
      $ mv crash-gcore-command-1.2.2/* extensions
      $ make extensions

  • This module's source files are self-contained in crash-gcore-command-1.2.2.tar.gz.

  • Changelog

  • Author: Daisuke Hatayama  <d.hatayama@jp.fujitsu.com>
spu.c spuctx
spus
spurq
  • Commands for viewing Cell/B.E. SPU's data

  • Requires kernel version >= 2.6.23-rc1

  • To build it, copy spu.c to the crash-<version>/extensions subdirectory, and from the top-level crash-<version> directory, enter:
      $ make extensions

  • Prior to installing it, it is necessary to load the debuginfo symbols of the spufs kernel module:
      crash> mod -s spufs

  • This module is part of IBM Software Development Kit (SDK) for Multicore Acceleration since Version 3.0.

  • Author: Lucio Correia  <luciojhc@br.ibm.com>
pykdump epython
crashinfo
xportshow
  • Execute Python scripts in crash environment

  • Gather basic data

  • View networking information

  • See Project page for more details

  • Author: Alex Sidorenko  <asid@hp.com>
qemu-vtop.c qemu-vtop
  • Translate a KVM guest physical address into the virtual and physical addresses of its KVM host.

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/qemu-vtop.c extensions
      $ make extensions
  • Prior to executing the command, it is necessary to load the debuginfo symbols of the kvm kernel module:
      crash> mod -s kvm

  • Author: Qiao Nuohan  <qiaonuohan@cn.fujitsu.com>
ipcs.c ipcs
  • Provide information about the System V IPCS facilities.

  • An updated version of this command was built into crash version 6.0.7.

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/ipcs.c extensions
      $ make extensions

  • Author: Qiao Nuohan  <qiaonuohan@cn.fujitsu.com>
pstruct.c pstruct
  • Print structure member data in a single line.

  • Requires crash utility version >= 6.0.7.

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/pstruct.c extensions
      $ make extensions

  • Author: Qiao Nuohan  <qiaonuohan@cn.fujitsu.com>
lscgroup.c lscgroup
  • Display active cgroups

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/lscgroup.c extensions
      $ make extensions

  • Author: Yongming Yu  <yuym.fnst@cn.fujitsu.com>
cgget.c cgget
  • Display cgroup parameters

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/cgget.c extensions
      $ make extensions

  • Author: Zhang Xiaohe  <zhangxh@cn.fujitsu.com>
swap_usage.c pswap
  • Display the swap consumption of a user process

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/swap_usage.c extensions
      $ make extensions

  • Author: Aaron Tomlin  <atomlin@redhat.com>
memutils.c memutils
  • Displays memory information

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/memutils.c extensions
      $ make extensions

  • Author: Vinayak Menon  <vinayakm.list@gmail.com>
ksm.c ksm
  • Display kernel samepage merging (KSM) information

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/ksm.c extensions
      $ make extensions

  • Author: Zhang Yanfei  <zhangyanfei@cn.fujitsu.com>
sockq.c sockq
  • Retrieve socket receive queue into a file

  • To build the module from the top-level crash-<version> directory, enter:
      $ cp <path-to>/sockq.c extensions
      $ make extensions

  • Author: Qiao Nuohan  <qiaonuohan@cn.fujitsu.com>
fp.c
fp.mk
fp
  • Obtain function parameters from stack frames

  • To build the module from the top-level crash-<version> directory, enter:
      $ wget https://raw.github.com/hziSot/crash-stack-parser/master/crash-parse-stack-7.0.1-ext.patch
      $ patch -p1 < crash-parse-stack-7.0.1-ext.patch
      $ make extensions
  • or:
      $ cp <path-to>/fp.c <path-to>/fp.mk extensions
      $ make extensions

  • Author: Alexandr Terekhov  <Alexandr_Terekhov@epam.com>
 
crash EPPIC scripts

EPPIC scripts require no compilation, but they do require that the eppic.so extension module be pre-loaded with extend, because eppic.so provides the load command required to load EPPIC scripts. To add the module to a running crash session, enter:

  crash> extend <path-to>/eppic.so

The module can be installed automatically if the extend command above is entered in either ./.crashrc or $HOME/.crashrc.

EPPIC scripts may be located anywhere. However, upon loading the eppic.so module, EPPIC scripts located in the /usr/share/eppic/crash or $HOME/.eppic directories will be loaded automatically. The command(s) contained in loaded EPPIC script(s) will appear in the crash help menu.

The EPPIC README and README.code files contain information regarding the format of eppic scripts.

The EPPIC sources contain a sample ipcs2 command, similar in nature to the built-in ipcs command. The ipcs2 script files will be located in the extensions/eppic/applications/crash/code directory, and the directory's contents should be copied to either /usr/share/eppic/crash or $HOME/.eppic. For example:

  $ make extensions
  ...
  $ cp -r extensions/eppic/applications/crash/code/* /usr/share/eppic/crash

Having done the above, upon loading the eppic.so module, the ipcs2 EPPIC command will be automatically loaded.

The EPPIC package website is here:

        http://code.google.com/p/eppic

Author: Luc Chouinard

 
crashdc: Crash Dump Data Collector

The crashdc data collector is a script that can be used in conjunction with the crash utility to automatically generate a text file containing major information about a newly generated crash dump. The package website is here:

        http://crashdc.sourceforge.net

Author: Louis Bouchard <louis.bouchard@canonical.com>

 
crash Python scripts

Pykdump scripts require no Python installed, but they do require the mpykdump.so extension module pre-loaded with extend. mpykdump.so provides built-in Python intepreter and needed pure Python libraries as well as Python bindings to crash. Loading the extension registers 'epython' command which can be used to execute Python programs.

To minimize the extension size, only parts of Python standard library are included in the extension file. If you need anything extra (e.g. XML/RPC) please contact the author.

The mpykdump.so extension file is a shared library with ZIP-archive appended at the end of it. You can use standard ZIP command to view the contents of it and add your own Python programs. In addition to generic epython command, two useful programs are included in the extension (see Wiki documentation on SF site for more details).

The package website is here:

        http://pykdump.sourceforge.net

Author: Alex Sidorenko  <asid@hp.com>

crashinfo
  • Print a brief summary of the dump running some tests

  • Using additional options, do other things (Swiss Army Knife approach - instead of many separate programs, use one with many options)

  • Author: Alex Sidorenko  <asid@hp.com>
xportshow
  • Print networking connections, routing tables etc. - similar to netstat

  • Author: Alex Sidorenko  <asid@hp.com>
 
crash-extscript

crash-extscript is an extension module command that can communicate with external scripts.

At times it may be necessary to execute a series of crash commands to arrive at a result. For example, the output of a crash command may be parsed for a particular element, which is then used in a subsequent command, and so on. There are cases when this may take several steps, and this utility can be used to automate those steps. Another use can be to execute a series of pre-defined crash commands, parse the output to get relevant information, and generate a bug report.

These are the components in contained in this package:

  1. A crash utility extension module called extscript.so that provides a crash command called extscript.
  2. A example perl script called perlfc.pl, which can talk to the extscript extension module command. This script can be used as an example to write similar utilities that can talk to extscript.
  3. A protocol definition for communication between extscript and the external script.

The external script is not executed as-is, but rather it is invoked by running the extscript command from the crash prompt. The external script is essentially run as a "server" by the crash utility when the extscript command is issued; the external script serves the crash utility by issuing crash commands.

To build the extension module from the top-level crash-<version> directory, enter:

  $ cp extscript.c extensions
  $ make extensions
  $ cp perlfc.pl .

Then from the crash prompt:

  crash> extend extensions/extscript.so
  crash> extscript -f perl -a perl -a ./perlfc.pl
  crash> extscript -b vmallocinfo

The first command loads the extscript.so module, which adds the extscript command to crash utility. The second command sets up the execution format similar to how arguments are passed to execlp(), passing the executable command's filename and the command arguments. The third command is the "bypass" command, which executes the specified command that is encoded in the perlfc.pl script. In this case vmallocinfo is one of the commands that is defined in perlfc.pl; its output will be similar to /proc/vmallocinfo, displayed on crash console.

The help command shows all the commands supported by the script and its usage:

  crash> extscript -b help

The perlfc.pl script is an example of how to write quick automation scripts to use the extscript extension of crash utility.

More details can be found in the README of the package

The package website is here:

        https://github.com/vinayakmenon/crash-extscript

Author: Vinayak Menon  <vinayakm.list@gmail.com>