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//proc/self/root/usr/share/doc/crash-5.1.8/README

CORE ANALYSIS SUITE

The core analysis suite is a self-contained tool that can be used to
  investigate either live systems, kernel core dumps created from the
  netdump and diskdump packages offered by Red Hat, the LKCD kernel patch
  or the mcore kernel patch available from Mission Critical Linux.

o  The tool is loosely based on the SVR4 crash command, but has been
     completely integrated with gdb in order to be able to display 
     formatted kernel data structures, disassemble source code, etc.
     
  o  The current set of available commands consist of common kernel core
     analysis tools such as a context-specific stack traces, source code
     disassembly, kernel variable displays, memory display, dumps of 
     linked-lists, etc.  In addition, any gdb command may be entered,
     which in turn will be passed onto the gdb module for execution.

o  There are several commands that delve deeper into specific kernel
     subsystems, which also serve as templates for kernel developers
     to create new commands for analysis of a specific area of interest.
     Adding a new command is a simple affair, and a quick recompile
     adds it to the command menu.

o  The intent is to make the tool independent of Linux version dependencies,
     building in recognition of major kernel code changes so as to adapt to 
     new kernel versions, while maintaining backwards compatibility.

A whitepaper with complete documentation concerning the use of this utility
  can be found here:
 
         http://people.redhat.com/anderson/crash_whitepaper
 
  These are the current prerequisites:

o  At this point, x86, ia64, x86_64, ppc64, arm, alpha, s390 and s390x-based
     kernels are supported.  Other architectures may be addressed in the future.

o  One size fits all -- the utility can be run on any Linux kernel version 
     from 2.2.5-15 through 2.6.*.

o  In order to contain debugging data, the top-level kernel Makefile's CFLAGS
     definition must contain the -g flag.  If not, the kernel must be rebuilt.
     For 2.2 kernels that are not built with -g, change the following line:

CFLAGS = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer

to:

CFLAGS = -g -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer

For 2.4 kernels that are not built with -g, change the following line:

CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -fno-strict-aliasing

to:

CFLAGS := -g $(CPPFLAGS) -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -fno-strict-aliasing

For 2.6 kernels that are not built with -g, change the following line:
 
        CFLAGS          := -Wall -Wstrict-prototypes -Wno-trigraphs \ 
 
     to:
 
        CFLAGS          := -g -Wall -Wstrict-prototypes -Wno-trigraphs \ 
 
     After the kernel is re-compiled, the uncompressed "vmlinux" kernel
     that is created in the top-level kernel build directory must be saved.

To build this utility, simply uncompress the tar file, enter the crash-5.1.8
  subdirectory, and type "make".  The initial build will take several minutes 
  because the gdb module must be configured and and built.  Alternatively, the
  crash source RPM file may be installed and built, and the resultant crash
  binary RPM file installed.  To build a 32-bit x86 binary that can be used to 
  analyze an arm dumpfile, type "make target=ARM".

If the tool is run against a crash dumpfile, two arguments are required, the
  uncompressed kernel name and the core dumpfile name.

If run on a live system, only the kernel name is required, because /dev/mem 
  will be used as the "dumpfile".  If the kernel file is stored in /boot, /,
  /boot/efi, or in any /usr/src subdirectory, then no command line arguments
  are required -- the first kernel found that matches /proc/version will be
  used as the namelist.
  
  For example, if the command name "crash" is kept intact in the Makefile,
  invoking it on a live system would look like this:

$ crash
    
    crash 5.1.8
    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.
     
    GNU gdb 7.0
    Copyright 2003 Free Software Foundation, Inc.
    GDB 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
    Type "show copying" to see the conditions.
    There is absolutely no warranty for GDB.  Type "show warranty" for details.
    This GDB was configured as "i686-pc-linux-gnu"..
     
          KERNEL: /boot/vmlinux
        DUMPFILE: /dev/mem
            CPUS: 1
            DATE: Fri Sep 16 15:01:12 2011
          UPTIME: 10 days, 22:55:18
    LOAD AVERAGE: 0.08, 0.03, 0.01
           TASKS: 42
        NODENAME: ha2.mclinux.com
         RELEASE: 2.4.0-test10
         VERSION: #11 SMP Thu Nov 4 15:09:25 EST 2000
         MACHINE: i686  (447 MHz)
	  MEMORY: 128 MB
             PID: 3621                                  
         COMMAND: "crash"
            TASK: c463c000  
             CPU: 0
           STATE: TASK_RUNNING (ACTIVE)

crash> help

*              files          mod            runq           union          
    alias          foreach        mount          search         vm             
    ascii          fuser          net            set            vtop           
    bt             gdb            p              sig            waitq          
    btop           help           ps             struct         whatis         
    dev            irq            pte            swap           wr             
    dis            kmem           ptob           sym            q              
    eval           list           ptov           sys            
    exit           log            rd             task           
    extend         mach           repeat         timer          
    
    crash version: 5.1.8    gdb version: 7.0
    For help on any command above, enter "help <command>".
    For help on input options, enter "help input".
    For help on output options, enter "help output".

crash> 
 
  When run on a dumpfile, both the kernel namelist and dumpfile must be 
  entered on the command line.  For example, when run on a core dump created
  by the Red Hat netdump or diskdump facilities:

$ crash vmlinux vmcore
 
    crash 5.1.8
    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.
     
    GNU gdb 7.0
    Copyright 2003 Free Software Foundation, Inc.
    GDB 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.
    Type "show copying" to see the conditions.
    There is absolutely no warranty for GDB.  Type "show warranty" for details.
    This GDB was configured as "i686-pc-linux-gnu"...
    
          KERNEL: vmlinux
        DUMPFILE: vmcore
            CPUS: 4
            DATE: Tue Mar  2 13:57:09 2004
          UPTIME: 00:02:40
    LOAD AVERAGE: 2.24, 0.96, 0.37
           TASKS: 70
        NODENAME: pro1.lab.boston.redhat.com
         RELEASE: 2.6.3-2.1.214.11smp
         VERSION: #1 SMP Tue Mar 2 10:58:27 EST 2004
         MACHINE: i686  (2785 Mhz)
          MEMORY: 512 MB
           PANIC: "Oops: 0002 [#1]" (check log for details)
             PID: 0
         COMMAND: "swapper"
            TASK: 22fa200  (1 of 4)  [THREAD_INFO: 2356000]
             CPU: 0
           STATE: TASK_RUNNING (PANIC)
    
    crash> 
 
  When run on a core dump created by the MCLX mcore patch:

$ crash vmlinux.17 lcore.cr.17

crash 5.1.8
    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.
     
    GNU gdb 7.0
    Copyright 2003 Free Software Foundation, Inc.
    GDB 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
    Type "show copying" to see the conditions.
    There is absolutely no warranty for GDB.  Type "show warranty" for details.
    This GDB was configured as "i686-pc-linux-gnu"...
    
          KERNEL: vmlinux.17                        
        DUMPFILE: lcore.cr.17
            CPUS: 1
            DATE: Wed Nov 10 19:54:47 1999
          UPTIME: 00:02:02
    LOAD AVERAGE: 0.82, 0.34, 0.12
           TASKS: 43
        NODENAME: ha3.mclinux.com
         RELEASE: 2.2.5-15
         VERSION: #39 Wed Nov 10 17:43:16 CST 1999
         MACHINE: i686  (501 MHz)
          MEMORY: 96 MB
           PANIC: "tulip_interrupt"
             PID: 286
         COMMAND: "in.rlogind"
            TASK: c0b3a000  
             CPU: 0
           STATE: TASK_RUNNING (PANIC)
    
    crash>

When run on an LKCD core dump, the command line would be like so:

$ crash vmlinux vmdump.0

The tool's environment is context-specific.  On a live system, the default
  context is the command itself; on a dump the default context will be the
  task that panicked.  The most commonly-used commands are:

set     - set a new task context by pid, task address, or cpu.
    bt      - backtrace of the current context, or as specified with arguments.
    p       - print the contents of a kernel variable.
    rd      - read memory, which may be either kernel virtual, user virtual, or
              physical.
    ps      - simple process listing.
    log     - dump the kernel log_buf.
    struct  - print the contents of a structure at a specified address.
    foreach - execute a command on all tasks, or those specified, in the system.
 
  Detailed help concerning the use of each of the commands in the menu above 
  may be displayed by entering "help command", where "command" is one of those 
  listed above.  Rather than getting bogged down in details here, simply
  run the help command on each of the commands above.  Note that many commands
  have multiple options so as to avoid the proliferation of command names.

Command output may be piped to external commands or redirected to files.
  Enter "help output" for details.

The command line history mechanism allows for command-line recall and 
  command-line editing.  Input files containing a set of crash commands may 
  be substituted for command-line input.  Enter "help input" for details.

Note that a .crashrc file (or .<your-command-name>rc if the name has been 
  changed), may contain any number of "set" or "alias" commands -- see the
  help pages on those two commands for details.
 
  Lastly, if a command is entered that is not recognized, it is checked
  against the kernel's list of variables, structure, union or typedef names, 
  and if found, the command is passed to "p", "struct", "union" or "whatis".
  That being the case, as long as a kernel variable/structure/union name is 
  different than any of the current commands.

(1) A kernel variable can be dumped by simply entering its name:
 
      crash> init_mm
      init_mm = $2 = {
        mmap = 0xc022d540, 
        mmap_avl = 0x0, 
        mmap_cache = 0x0, 
        pgd = 0xc0101000, 
        count = {
          counter = 0x6
        }, 
        map_count = 0x1, 
        mmap_sem = {
          count = {
            counter = 0x1
          }, 
          waking = 0x0, 
          wait = 0x0
        }, 
        context = 0x0, 
        start_code = 0xc0000000, 
        end_code = 0xc022b4c8,
        end_data = c0250388,
        ...
      
  (2) A structure or can be dumped simply by entering its name and address:

crash> vm_area_struct c5ba3910
      struct vm_area_struct {
        vm_mm = 0xc3ae3210, 
        vm_start = 0x821b000, 
        vm_end = 0x8692000, 
        vm_next = 0xc5ba3890, 
        vm_page_prot = {
          pgprot = 0x25
        }, 
        vm_flags = 0x77, 
        vm_avl_height = 0x4, 
        vm_avl_left = 0xc0499540, 
        vm_avl_right = 0xc0499f40, 
        vm_next_share = 0xc04993c0, 
        vm_pprev_share = 0xc0499060, 
        vm_ops = 0x0, 
        vm_offset = 0x0, 
        vm_file = 0x0, 
        vm_pte = 0x0
      }

The crash utility has been designed to facilitate the task of adding new 
  commands.  New commands may be permanently compiled into the crash executable,
  or dynamically added during runtime using shared object files.
 
  To permanently add a new command to the crash executable's menu:

1. For a command named "xxx", put a reference to cmd_xxx() in defs.h.
   
    2. Add cmd_xxx into the base_command_table[] array in global_data.c.

3. Write cmd_xxx(), putting it in one of the appropriate files.  Look at 
       the other commands for guidance on getting symbolic data, reading
       memory, displaying data, etc...

4. Recompile and run.

Note that while the initial compile of crash, which configures and compiles
  the gdb module, takes several minutes, subsequent re-compiles to do such
  things as add new commands or fix bugs just takes a few seconds.

Alternatively, you can create shared object library files consisting of
  crash command extensions, that can be dynamically linked into the crash
  executable during runtime or during initialization.  This will allow the
  the same shared object to be used with subsequent crash releases without
  having to re-merge the command's code into each new set of crash sources.
  The dynamically linked-in commands will automatically show up in the crash
  help menu.  For details, enter "help extend" during runtime, or enter
  "crash -h extend" from the shell command line.