crash utility help page:  mod


NAME
  mod - module information and loading of symbols and debugging data

SYNOPSIS
  mod -s module [objfile] | -d module | -S [directory] [-D|-t|-r|-R|-o|-g]

DESCRIPTION
  With no arguments, this command displays basic information of the currently
  installed modules, consisting of the module address, name, size, the
  object file name (if known), and whether the module was compiled with
  CONFIG_KALLSYMS.
 
  The arguments are concerned with with the loading or deleting of symbolic
  and debugging data from a module's object file.  A modules's object file
  always contains symbolic data (symbol names and addresses), but contains
  debugging data only if the module was compiled with the -g CFLAG.  In
  addition, the module may have compiled with CONFIG_KALLSYMS, which means
  that the module's symbolic data will have been loaded into the kernel's
  address space when it was installed.  If the module was not compiled with
  CONFIG_KALLSYMS, then only the module's exported symbols will be loaded
  into the kernel's address space.  Therefore, for the purpose of this
  command, it should noted that a kernel module may have been compiled in
  one of following manners:

  1. If the module was built without CONFIG_KALLSYMS and without the -g CFLAG,
     then the loading of the module's additional non-exported symbols can
     be accomplished with this command.
  2. If the module was built with CONFIG_KALLSYMS, but without the -g CFLAG,
     then there is no benefit in loading the symbols from the module object
     file, because all of the module's symbols will have been loaded into the
     kernel's address space when it was installed.
  3. If the module was built with CONFIG_KALLSYMS and with the the -g CFLAG,
     then the loading of the module's debugging data can be accomplished
     with this command.
  4. If the module was built without CONFIG_KALLSYMS but with the -g CFLAG,
     then the loading of the both module's symbolic and debugging data can
     be accomplished with this command.
 
  -s module [objfile]  Loads symbolic and debugging data from the object file
                       for the module specified.  If no objfile argument is
                       appended, a search will be made for an object file
                       consisting of the module name with a .o or .ko suffix,
                       starting at the /lib/modules/<release> directory on
                       the host system, or if not found there, starting at the
                       directory containing the kernel namelist file.  If an
                       objfile argument is appended, then that file will be
                       used.
            -d module  Deletes the symbolic and debugging data of the module
                       specified.
       -S [directory]  Load symbolic and debugging data from the object file
                       for all loaded modules.  For each module, a search
                       will be made for an object file consisting of the
                       module name with a .o or .ko suffix, starting at the
                       /lib/modules/<release> directory of the host system,
                       or if not found there, starting at the directory
                       containing the kernel namelist file.  If a directory
                       argument is appended, then the search will be restricted
                       to that directory.
                   -D  Deletes the symbolic and debugging data of all modules.
                   -t  Display the contents of the module's "taints" bitmask
                       if it is non-zero.  When possible, the "taints" bits
                       are translated to symbolic letters of the taint type;
                       otherwise the hexadecimal value is shown.  In older
                       kernels, the contents of the "license_gplok" field is
                       displayed in hexadecimal; the field may be either a 
                       bitmask or a boolean, depending upon the kernel version.
                       The relevant kernel sources should be consulted for the
                       meaning of the letter(s) or hexadecimal bit value(s). 
                       For modules that have a "gpgsig_ok" field that is zero
                       (unsigned), the notation "(U)" is shown.
                   -r  Passes the -readnow flag to the embedded gdb module,
                       which will override the two-stage strategy that it uses
                       for reading symbol tables from module object files.
                   -R  Reinitialize module data. All currently-loaded symbolic
                       and debugging data will be deleted, and the installed
                       module list will be updated (live system only).
                   -g  When used with -s or -S, add a module object's section
                       start and end addresses to its symbol list.
                   -o  Load module symbols with old mechanism.
 
  If the crash session was invoked with the "--mod <directory>" option, or
  a CRASH_MODULE_PATH environment variable exists, then /lib/modules/<release>
  will be overridden as the default directory tree that is searched for module
  object files.
 
  After symbolic and debugging data have been loaded, backtraces and text
  disassembly will be displayed appropriately.  Depending upon the processor
  architecture, data may also printed symbolically with the "p" command;
  at a minimum, the "rd" command may be used with module data symbols.
 
  If crash can recognize that the set of modules has changed while running a
  session on a live kernel, the module data will be reinitialized the next
  time this command is run; the -r option forces the reinitialization.

EXAMPLES
  Display the currently-installed modules:

    crash> mod
     MODULE   NAME         SIZE  OBJECT FILE
    c8019000  soundcore    2788  (not loaded)
    c801b000  soundlow      336  (not loaded)
    c801d000  sound       59864  (not loaded)
    c802d000  ad1848      15728  (not loaded)
    c8032000  uart401      6000  (not loaded)
    c8035000  cs4232       2472  (not loaded)
    c8043000  opl3        11048  (not loaded)
    c8047000  3c59x       18152  (not loaded)
    c804d000  sunrpc      53796  (not loaded)
    c805c000  lockd       31528  (not loaded)
    c8065000  nfsd       151896  (not loaded)
    c8092000  nfs         29752  (not loaded)
 
  Display the currently-installed modules on a system where all modules were
  compiled with CONFIG_KALLSYMS:
 
    crash> mod
     MODULE   NAME              SIZE  OBJECT FILE
    e080d000  jbd              57016  (not loaded)  [CONFIG_KALLSYMS]
    e081e000  ext3             92360  (not loaded)  [CONFIG_KALLSYMS]
    e0838000  usbcore          83168  (not loaded)  [CONFIG_KALLSYMS]
    e0850000  usb-uhci         27532  (not loaded)  [CONFIG_KALLSYMS]
    e085a000  ehci-hcd         20904  (not loaded)  [CONFIG_KALLSYMS]
    e0865000  input             6208  (not loaded)  [CONFIG_KALLSYMS]
    e086a000  hid              22404  (not loaded)  [CONFIG_KALLSYMS]
    e0873000  mousedev          5688  (not loaded)  [CONFIG_KALLSYMS]
    e0878000  keybdev           2976  (not loaded)  [CONFIG_KALLSYMS]
    e08fd000  cdrom            34144  (not loaded)  [CONFIG_KALLSYMS]
    e0909000  ide-cd           35776  (not loaded)  [CONFIG_KALLSYMS]
    e0915000  scsi_mod        117928  (not loaded)  [CONFIG_KALLSYMS]
    e0935000  ide-scsi         12752  (not loaded)  [CONFIG_KALLSYMS]
    e093c000  microcode         5248  (not loaded)  [CONFIG_KALLSYMS]
    e0943000  sr_mod           18136  (not loaded)  [CONFIG_KALLSYMS]
    e0956000  floppy           59056  (not loaded)  [CONFIG_KALLSYMS]
    e0966000  sg               38060  (not loaded)  [CONFIG_KALLSYMS]
    e0971000  ip_tables        16544  (not loaded)  [CONFIG_KALLSYMS]
    e097d000  iptable_filter    2412  (not loaded)  [CONFIG_KALLSYMS]
    e097f000  e1000            76096  (not loaded)  [CONFIG_KALLSYMS]
    e09ba000  autofs           13780  (not loaded)  [CONFIG_KALLSYMS]
    e09c1000  parport          39072  (not loaded)  [CONFIG_KALLSYMS]
    e09ce000  lp                9220  (not loaded)  [CONFIG_KALLSYMS]
    e09d4000  parport_pc       19204  (not loaded)  [CONFIG_KALLSYMS]
    e09e2000  agpgart          59128  (not loaded)  [CONFIG_KALLSYMS]
    e0a1a000  radeon          117156  (not loaded)  [CONFIG_KALLSYMS]
    e2dc7000  sunrpc           91996  (not loaded)  [CONFIG_KALLSYMS]
    e2de1000  lockd            60624  (not loaded)  [CONFIG_KALLSYMS]
    e2df3000  nfs              96880  (not loaded)  [CONFIG_KALLSYMS]
 
  Load the symbolic and debugging data of all modules:

    crash> mod -S
     MODULE   NAME         SIZE  OBJECT FILE
    c8019000  soundcore    2788  /lib/modules/2.2.5-15/misc/soundcore.o
    c801b000  soundlow      336  /lib/modules/2.2.5-15/misc/soundlow.o
    c801d000  sound       59864  /lib/modules/2.2.5-15/misc/sound.o
    c802d000  ad1848      15728  /lib/modules/2.2.5-15/misc/ad1848.o
    c8032000  uart401      6000  /lib/modules/2.2.5-15/misc/uart401.o
    c8035000  cs4232       2472  /lib/modules/2.2.5-15/misc/cs4232.o
    c8043000  opl3        11048  /lib/modules/2.2.5-15/misc/opl3.o
    c8047000  3c59x       18152  /lib/modules/2.2.5-15/net/3c59x.o
    c804d000  sunrpc      53796  /lib/modules/2.2.5-15/misc/sunrpc.o
    c805c000  lockd       31528  /lib/modules/2.2.5-15/fs/lockd.o
    c8065000  nfsd       151896  /lib/modules/2.2.5-15/fs/nfsd.o
    c8092000  nfs         29752  /lib/modules/2.2.5-15/fs/nfs.o
    
  Load the symbolic and debugging data of the soundcore module from its
  known location:
 
    crash> mod -s soundcore
     MODULE   NAME         SIZE  OBJECT FILE
    c8019000  soundcore    2788  /lib/modules/2.2.5-15/misc/soundcore.o
    
  Delete the current symbolic and debugging data of the soundcore module, 
  and then re-load it from a specified object file:
 
    crash> mod -d soundcore
    crash> mod -s soundcore /tmp/soundcore.o
     MODULE   NAME         SIZE  OBJECT FILE
    c8019000  soundcore    2788  /tmp/soundcore.o
 
  After installing a new kernel module on a live system, reinitialize the
  installed module list:

    crash> !insmod mdacon
    crash> mod
    mod: NOTE: modules have changed on this system -- reinitializing
     MODULE   NAME         SIZE  OBJECT FILE
    c8019000  soundcore    2788  (not loaded)
    c801b000  soundlow      336  (not loaded)
    c801d000  sound       59864  (not loaded)
    c802d000  ad1848      15728  (not loaded)
    c8032000  uart401      6000  (not loaded)
    c8035000  cs4232       2472  (not loaded)
    c8043000  opl3        11048  (not loaded)
    c8047000  3c59x       18152  (not loaded)
    c804d000  sunrpc      53796  (not loaded)
    c805c000  lockd       31528  (not loaded)
    c8065000  nfs         29752  (not loaded)
    c806e000  autofs       9316  (not loaded)
    c8072000  nfsd       151896  (not loaded)
    c80a1000  mdacon       3556  (not loaded)
 
  Display modules that are "tainted", where in this case
  where they are proprietary and unsigned:
 
    crash> mod -t
    NAME      TAINT
    vxspec    P(U)
    vxportal  P(U)
    fdd       P(U)
    vxfs      P(U)
    vxdmp     P(U)
    vxio      P(U)
    vxglm     P(U)
    vxgms     P(U)
    vxodm     P(U)