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mdb

Name
     mdb - modular debugger

Synopsis
     mdb [-fkmuwyAFKMSUW] [+-o option] [-p pid] [-s distance]
          [-I path] [-L path] [-P prompt] [-R root]
          [-V dis-version] [object [core] | core | suffix]

Description
  Introduction
     The mdb utility  is  an  extensible  utility  for  low-level
     debugging  and editing of the live operating system, operat-
     ing system crash dumps, user processes,  user  process  core
     dumps,  and object files. For a more detailed description of
     mdb features, refer to the manual,  Oracle  Solaris  Modular
     Debugger Guide.


     Debugging is the process  of  analyzing  the  execution  and
     state  of  a  software  program  in order to remove defects.
     Traditional debugging tools provide facilities for execution
     control  so  that  programmers  can re-execute programs in a
     controlled environment and display the current state of pro-
     gram  data  or  evaluate  expressions in the source language
     used to develop the program.


     Unfortunately, these techniques are often inappropriate  for
     debugging complex software systems such as an operating sys-
     tem, where bugs might not be reproducible and program  state
     is  massive  and  distributed,  for programs that are highly
     optimized, have had their debug information removed, or  are
     themselves low-level debugging tools, or for customer situa-
     tions where the developer can only access post-mortem infor-
     mation.


     mdb  provides  a  completely  customizable  environment  for
     debugging  these programs and scenarios, including a dynamic
     module facility that programmers can use to implement  their
     own debugging commands to perform program-specific analysis.
     Each mdb module can  be  used  to  examine  the  program  in
     several different contexts, including live and post-mortem.

  Definitions
     The target is the program being inspected by  the  debugger.
     mdb  currently  provides  support for the following types of
     targets: user processes, user process core files,  the  live
     operating  system  (via /dev/kmem and /dev/ksyms), operating
     system crash dumps, user process images recorded  inside  an
     operating  system  crash  dump,  ELF  object  files, and raw
     binary files. Each target exports a standard set of  proper-
     ties, including one or more address spaces, one or more sym-
     bol tables, a set of load objects, and a set of threads that
     can be examined using the debugger commands described below.


     A debugger command, or dcmd (pronounced dee-command) in  mdb
     terminology,  is  a  routine in the debugger that can access
     any of the properties of the current target. mdb parses com-
     mands from standard input, and then executes the correspond-
     ing dcmds. Each dcmd can also accept a  list  of  string  or
     numerical  arguments,  as  shown  in  the syntax description
     below. mdb contains  a  set  of  built-in  dcmds,  described
     below,  that  are  always available. You can also extend the
     capabilities of mdb itself by writing  your  own  dcmds,  as
     described in the Oracle Solaris Modular Debugger Guide.


     A walker is a set of routines that describe how to walk,  or
     iterate,  through  the elements of a particular program data
     structure. A walker encapsulates the data structure's imple-
     mentation  from dcmds and from mdb itself. You can use walk-
     ers interactively, or use them as a primitive to build other
     dcmds  or  walkers.  As  with  dcmds,  you can extend mdb by
     implementing your own walkers as part of a debugger module.


     A debugger module, or dmod (pronounced dee-mod), is a dynam-
     ically loaded library containing a set of dcmds and walkers.
     During  initialization,   mdb   attempts   to   load   dmods
     corresponding to the load objects present in the target. You
     can subsequently load or unload dmods at any time while run-
     ning  mdb. mdb ships with a set of standard dmods for debug-
     ging the Solaris kernel. The Oracle Solaris Modular Debugger
     Guide  contains  more  information  on  developing  your own
     debugger modules.


     A macro file is a text file containing a set of commands  to
     execute. Macro files are typically used to automate the pro-
     cess of displaying a simple  data  structure.  mdb  provides
     complete  backward  compatibility for the execution of macro
     files written  for  adb(1),  and  the  Solaris  installation
     includes a set of macro files for debugging the Solaris ker-
     nel that can be used with either tool.

  Syntax
     The debugger processes  commands  from  standard  input.  If
     standard  input is a terminal, mdb provides terminal editing
     capabilities. mdb can also process commands from macro files
     and  from dcmd pipelines, described below. The language syn-
     tax is designed around the concept of computing the value of
     an  expression  (typically  a memory address in the target),
     and then applying  a  dcmd  to  that  address.  The  current
     address  location  is  referred  to as dot, and its value is
     referenced using ``.''.


     A metacharacter is one of the following characters:

       [   ]   |   !   /   \   ?   =   >   $   :   ;
                   NEWLINE   SPACE   TAB




     A blank is a TAB or a SPACE. A word is a sequence of charac-
     ters  separated  by  one  or more non-quoted metacharacters.
     Some of the metacharacters only function  as  delimiters  in
     certain  contexts,  as  described  below. An identifier is a
     sequence  of  letters,  digits,  underscores,  periods,   or
     backquotes  beginning  with a letter, underscore, or period.
     Identifiers are used as the  names  of  symbols,  variables,
     dcmds,  and  walkers. Commands are delimited by a NEWLINE or
     semicolon ( ; ).


     A dcmd is denoted by one of the following words or metachar-
     acters:

       /   \   ?   =   >   $character   :character  ::identifier




     dcmds named by metacharacters or prefixed by a single $ or :
     are  provided  as built-in operators, and implement complete
     compatibility with the command  set  of  the  legacy  adb(1)
     utility.  Once a dcmd has been parsed, the /, \, ?, =, >, $,
     and : characters are no longer recognized as  metacharacters
     until the termination of the argument list.


     A simple-command is a dcmd followed by a sequence of zero or
     more  blank-separated  words.  The words are passed as argu-
     ments to the invoked dcmd, except as specified under Quoting
     and  Arithmetic  Expansion  below. Each dcmd returns an exit
     status that indicates it was either successful,  failed,  or
     was invoked with invalid arguments.


     A pipeline is a sequence of  one  or  more  simple  commands
     separated by |. Unlike the shell, dcmds in mdb pipelines are
     not executed as separate processes. After the  pipeline  has
     been  parsed,  each  dcmd  is  invoked in order from left to
     right.  Each  dcmd's  output  is  processed  and  stored  as
     described  under  dcmd  Pipelines  below. Once the left-hand
     dcmd is complete, its processed output is used as input  for
     the next dcmd in the pipeline. If any dcmd does not return a
     successful exit status, the pipeline is aborted.


     An expression is a sequence of words that  is  evaluated  to
     compute  a  64-bit  unsigned  integer  value.  The words are
     evaluated using the rules described under Arithmetic  Expan-
     sion below.

  Commands
     A command is one of the following:

     pipeline [! word ...] [ ; ]
         A simple-command or pipeline can be optionally  suffixed
         with  the  !  character,  indicating  that  the debugger
         should open a pipe(2) and send the  standard  output  of
         the last dcmd in the mdb pipeline to an external process
         created by executing $SHELL -c followed  by  the  string
         formed by concatenating the words after the ! character.
         For more details, refer to Shell Escapes below.


     expression pipeline [! word ...] [ ; ]
         A simple-command or pipeline can  be  prefixed  with  an
         expression.  Before execution of the pipeline, the value
         of dot (the variable denoted by ``.'')  is  set  to  the
         value of the expression.


     expression , expression pipeline [! word ...] [ ; ]
         A simple-command or pipeline can be  prefixed  with  two
         expressions. The first is evaluated to determine the new
         value of dot, and the second is evaluated to determine a
         repeat  count  for  the first dcmd in the pipeline. This
         dcmd is executed count times before the next dcmd in the
         pipeline  is  executed. The repeat count only applies to
         the first dcmd in the pipeline.


     , expression pipeline [! word ...] [ ; ]
         If the initial expression is omitted, dot is  not  modi-
         fied  but  the  first  dcmd  in the pipeline is repeated
         according to the value of the expression.

     expression [! word ...] [ ; ]
         A command can consist only of an arithmetic  expression.
         The  expression is evaluated and the dot variable is set
         to its value, and then the previous dcmd  and  arguments
         are executed using the new value of dot.


     expression, expression [! word ...] [ ; ]
         A command can consist  only  of  a  dot  expression  and
         repeat  count  expression. After dot is set to the value
         of the first expression, the previous dcmd and arguments
         are repeatedly executed the number of times specified by
         the value of the second expression.


     , expression [! word ...] [ ; ]
         If the initial expression is omitted, dot is  not  modi-
         fied  but the previous dcmd and arguments are repeatedly
         executed the number of times specified by the  value  of
         the count expression.


     ! word ... [ ; ]
         If the command begins with the ! character, no dcmds are
         executed and the debugger simply executes $SHELL -c fol-
         lowed by the string formed by  concatenating  the  words
         after the ! character.


  Comments
     A word beginning with // causes that word and all the subse-
     quent characters up to a NEWLINE to be ignored.

  Arithmetic Expansion
     Arithmetic expansion is performed when  an  mdb  command  is
     preceded  by  an  optional  expression  representing a start
     address, or a start address and a repeat  count.  Arithmetic
     expansion can also be performed to compute a numerical argu-
     ment for a dcmd. An arithmetic expression can appear  in  an
     argument list enclosed in square brackets preceded by a dol-
     lar sign ($[ expression ]), and is replaced by the value  of
     the expression.


     Expressions can contain any of the following special words:

     integer
         The specified integer value. Integer values can be  pre-
         fixed  with 0i or 0I to indicate binary values, 0o or 0O
         to indicate octal values, 0t or 0T to  indicate  decimal
         values, and 0x or 0X to indicate hexadecimal values (the
         default).


     0[tT][0-9]+.[0-9]+
         The specified decimal floating point value, converted to
         its IEEE double-precision floating point representation.


     `cccccccc'
         The integer value computed by converting each  character
         to  a byte equal to its ASCII value. Up to eight charac-
         ters can be specified in a character  constant.  Charac-
         ters  are  packed  into  the  integer  in  reverse order
         (right-to-left) beginning at the least significant byte.


     <identifier
         The value of the variable named by identifier.


     identifier
         The value of the symbol named by identifier.


     (expression)
         The value of expression.


     .
         The value of dot.


     &
         The most recent value of dot used to execute a dcmd.


     +
         The value of dot incremented by the current increment.


     ^
         The value of dot decremented by the current increment.

     The increment is a global variable  that  stores  the  total
     bytes read by the last formatting dcmd. For more information
     on the increment, refer  to  the  discussion  of  Formatting
     dcmds below.


     Unary operators are right associative and have  higher  pre-
     cedence than binary operators. The unary operators are:

     #expression
         Logical negation.


     ~expression
         Bitwise complement.


     -expression
         Integer negation.


     %expression
         The value of a pointer-sized quantity at the object file
         location  corresponding to virtual address expression in
         the target's virtual address space.


     %/[csil]/expression
         The value of a char, short, int, or long-sized  quantity
         at  the  object  file  location corresponding to virtual
         address  expression  in  the  target's  virtual  address
         space.


     %/[1248]/expression
         The value of a one, two, four, or eight-byte quantity at
         the   object  file  location  corresponding  to  virtual
         address  expression  in  the  target's  virtual  address
         space.


     *expression
         The value of a pointer-sized quantity at virtual address
         expression in the target's virtual address space.


     */[csil]/expression
         The value of a char, short, int, or long-sized  quantity
         at  virtual  address  expression in the target's virtual
         address space.


     */[1248]/expression
         The value of a one, two, four, or eight-byte quantity at
         virtual  address  expression  in  the  target's  virtual
         address space.



     Binary operators are left associative and  have  lower  pre-
     cedence than unary operators. The binary operators, in order
     of precedence from highest to lowest, are:

     *
         Integer multiplication.


     %
         Integer division.


     #
         Left-hand side rounded up to next multiple of right-hand
         side.


     +
         Integer addition.


     -
         Integer subtraction.


     <<
         Bitwise shift left.


     >>
         Bitwise shift right.


     ==
         Logical equality.

     !=
         Logical inequality.


     &
         Bitwise AND.


     ^
         Bitwise exclusive OR.


     |
         Bitwise inclusive OR.


  Quoting
     Each metacharacter described above (see Syntax) terminates a
     word unless quoted. Characters can be quoted (forcing mdb to
     interpret each character as itself without any special  sig-
     nificance)  by  enclosing  them in a pair of single (' `) or
     double (" ") quote  marks.  A  single  quote  cannot  appear
     within  single  quotes. Inside double quotes, mdb recognizes
     the C programming language character escape sequences.

  Shell Escapes
     The ! character can be used to create a pipeline between  an
     mdb  command and the user's shell. If the $SHELL environment
     variable is set, mdb forks and execs this program for  shell
     escapes;  otherwise  /bin/sh  is  used. The shell is invoked
     with the -c option followed  by  a  string  formed  by  con-
     catenating  the words after the ! character. The ! character
     takes precedence over all other metacharacters, except semi-
     colon  (;) and NEWLINE. Once a shell escape is detected, the
     remaining characters up to the next semicolon or NEWLINE are
     passed  as is to the shell. The output of shell commands can
     not be piped to mdb dcmds.  Commands  executed  by  a  shell
     escape  have their output sent directly to the terminal, not
     to mdb.

  Variables
     A variable is  a  variable  name,  a  corresponding  integer
     value,  and  a  set  of  attributes.  A  variable  name is a
     sequence of letters,  digits,  underscores,  or  periods.  A
     variable  can  be  assigned  a  value  using  the  > dcmd or
     ::typeset dcmd, and its attributes can be manipulated  using
     the  ::typeset dcmd. Each variable's value is represented as
     a 64-bit unsigned integer. A variable can have one  or  more
     of  the  following attributes: read-only (cannot be modified
     by the user), persistent (cannot be unset by the user),  and
     tagged (user-defined indicator).


     The following variables are defined as persistent:

     0
         The most recent value printed using the /, \,  ?,  or  =
         dcmd.


     9
         The most recent count used with the $< dcmd.


     b
         The virtual address of the base of the data section.


     d
         The size of the data section in bytes.


     e
         The virtual address of the entry point.


     m
         The initial bytes (magic number) of the target's primary
         object  file,  or  zero  if no object file has been read
         yet.


     t
         The size of the text section in bytes.


     hits
         The count of the number of times  the  matched  software
         event  specifier  has been matched. See Event Callbacks,
         below.


     thread
         The thread  identifier  of  the  current  representative
         thread.  The  value  of  the  identifier  depends on the
         threading model used by the current target.  See  Thread
         Support, below.

     In addition, the mdb kernel and process targets  export  the
     current  values  of the representative thread's register set
     as named variables. The names of these variables  depend  on
     the target's platform and instruction set architecture.

  Symbol Name Resolution
     As explained in the Syntax description above, a symbol iden-
     tifier  present  in  an  expression context evaluates to the
     value of this symbol. The value typically denotes  the  vir-
     tual  address  of  the storage associated with the symbol in
     the target's virtual address space.  A  target  can  support
     multiple symbol tables including, but not limited to, a pri-
     mary executable  symbol  table,  a  primary  dynamic  symbol
     table, a run-time link-editor symbol table, and standard and
     dynamic symbol tables for each of a number of  load  objects
     (such  as  shared  libraries  in  a  user process, or kernel
     modules  in  the  Solaris  kernel).  The  target   typically
     searches  the  primary executable's symbol tables first, and
     then one or more of the other symbol tables. Notice that ELF
     symbol tables only contain entries for external, global, and
     static symbols; automatic symbols do not appear in the  sym-
     bol tables processed by mdb.


     Additionally, mdb provides  a  private  user-defined  symbol
     table  that  is  searched  prior to any of the target symbol
     tables. The private symbol table is initially empty, and can
     be manipulated using the ::nmadd and ::nmdel dcmds. The ::nm
     -P option can be used to display the contents of the private
     symbol  table.  The  private symbol table allows the user to
     create symbol definitions for program functions or data that
     were  either  missing  from the original program or stripped
     out. These definitions are then used whenever mdb converts a
     symbolic  name  to  an address, or an address to the nearest
     symbol.


     As targets contain multiple symbol tables, and  each  symbol
     table  can  include symbols from multiple object files, dif-
     ferent symbols with the same name can exist.  mdb  uses  the
     backquote (`) character as a symbol name scoping operator to
     allow the programmer to obtain the value of the desired sym-
     bol  in this situation. The programmer can specify the scope
     used to resolve a symbol name  as  either:  object`name,  or
     file`name, or object`file`name. The object identifier refers
     to the name of a load object. The file identifier refers  to
     the  basename  of  a  source  file that has a symbol of type
     STT_FILE in the specified object's symbol table. The  object
     identifier's interpretation depends on the target type.

     The mdb kernel target expects object to specify the basename
     of a loaded kernel module. For example, the symbol name

       specfs`_init




     evaluates to the value of the _init  symbol  in  the  specfs
     kernel module.


     The mdb process target expects object to specify the name of
     the  executable  or  of a loaded shared library. It can take
     any of the following forms:

         1.   An  exact  match  (that  is,  a   full   pathname):
              /usr/lib/libc.so.1

         2.   An exact basename match: libc.so.1

         3.   An initial basename match up  to  a  ``.''  suffix:
              libc.so or libc

         4.   The literal string a.out is accepted  as  an  alias
              for the executable.


     The process target  also  accepts  any  of  the  four  forms
     described  above preceded by an optional link-map id (lmid).
     The lmid prefix is specified by an initial "LM" followed  by
     the  link-map  id  in  hexadecimal followed by an additional
     backquote. For example, the symbol name

       LM0`libc.so.1`_init




     evaluates to the value of the _init symbol in the  libc.so.1
     library  that  is  loaded  on  link-map  0 (LM_ID_BASE). The
     link-map specifier can be necessary to resolve symbol naming
     conflicts  in  the  event that the same library is loaded on
     more than one link map. For more information on  link  maps,
     refer  to  the  Oracle  Solaris  11.3  Linkers and Libraries
     Guide and dlopen(3C).  Link-map  identifiers  are  displayed
     when  symbols  are  printed  according to the setting of the
     showlmid option, as described under OPTIONS.


     In the case of a naming conflict between symbols and hexade-
     cimal  integer values, mdb attempts to evaluate an ambiguous
     token as a symbol first, before evaluating it as an  integer
     value.  For  example,  the  token  f can either refer to the
     decimal integer  value  15  specified  in  hexadecimal  (the
     default  base),  or  to  a  global  variable  named f in the
     target's symbol table. If a symbol with an ambiguous name is
     present,  the  integer  value  can  be specified by using an
     explicit 0x or 0X prefix.

  dcmd and Walker Name Resolution
     As described earlier, each mdb dmod provides a set of  dcmds
     and  walkers. dcmds and walkers are tracked in two distinct,
     global namespaces. mdb also keeps track of a dcmd and walker
     namespace associated with each dmod. Identically named dcmds
     or walkers within a given dmod are not allowed: a dmod  with
     this  type  of naming conflict fails to load. Name conflicts
     between dcmds or walkers from different dmods are allowed in
     the  global  namespace. In the case of a conflict, the first
     dcmd or walker with that particular name  to  be  loaded  is
     given  precedence in the global namespace. Alternate defini-
     tions are kept in a list in load order. The backquote  char-
     acter  (`) can be used in a dcmd or walker name as a scoping
     operator to select an alternate definition. For example,  if
     dmods  m1  and  m2  each  provide a dcmd d, and m1 is loaded
     prior to m2, then:

     ::d
         Executes m1's definition of d.


     ::m1`d
         Executes m1's definition of d.


     ::m2`d
         Executes m2's definition of d.



     If module m1 were now unloaded, the next dcmd on the  global
     definition  list (m2`d) would be promoted to global visibil-
     ity. The current definition of  a  dcmd  or  walker  can  be
     determined using the ::which dcmd, described below. The glo-
     bal definition list can be displayed using  the  ::which  -v
     option.

  dcmd Pipelines
     dcmds can be composed into a pipeline using the |  operator.
     The purpose of a pipeline is to pass a list of values, typi-
     cally virtual addresses, from one dcmd or walker to another.
     Pipeline stages might be used to map a pointer from one type
     of data structure to  a  pointer  to  a  corresponding  data
     structure,  to  sort  a  list of addresses, or to select the
     addresses of structures with certain properties.


     mdb executes each dcmd in the pipeline in order from left to
     right. The leftmost dcmd is executed using the current value
     of dot, or using the value specified by an explicit  expres-
     sion  at  the  start  of  the  command. When a | operator is
     encountered, mdb creates a pipe (a  shared  buffer)  between
     the  output  of the dcmd to its left and the mdb parser, and
     an empty list of values. As the dcmd executes, its  standard
     output is placed in the pipe and then consumed and evaluated
     by the parser, as if mdb were reading this data  from  stan-
     dard  input. Each line must consist of an arithmetic expres-
     sion terminated by a NEWLINE or semicolon (;). The value  of
     the  expression is appended to the list of values associated
     with the pipe. If a syntax error is detected,  the  pipeline
     is aborted.


     When the dcmd to the left of a  |  operator  completes,  the
     list  of  values  associated  with  the pipe is then used to
     invoke the dcmd to the right of the  |  operator.  For  each
     value  in  the list, dot is set to this value and the right-
     hand dcmd is executed. Only the rightmost dcmd in the  pipe-
     line  has its output printed to standard output. If any dcmd
     in the pipeline produces output  to  standard  error,  these
     messages  are printed directly to standard error and are not
     processed as part of the pipeline.

  Signal Handling
     The debugger ignores the PIPE and QUIT signals. The INT sig-
     nal  aborts  the  command  that  is currently executing. The
     debugger intercepts and provides special  handling  for  the
     ILL,  TRAP, EMT, FPE, BUS, and SEGV signals. If any of these
     signals are generated  asynchronously  (that  is,  delivered
     from another process using kill(2)), mdb restores the signal
     to its default disposition and dump core. However, if any of
     these  signals  are  generated synchronously by the debugger
     process itself and a dcmd from an externally loaded dmod  is
     currently  executing,  and standard input is a terminal, mdb
     provides a menu of choices allowing the user to force a core
     dump, quit without producing a core dump, stop for attach by
     a debugger, or attempt to resume. The resume  option  aborts
     all  active  commands  and  unload  the  dmod whose dcmd was
     active at the time the fault occurred. It can then be subse-
     quently  re-loaded  by  the user. The resume option provides
     limited protection against buggy dcmds. Refer  to  WARNINGS,
     Use  of  the Error Recovery Mechanism, below for information
     about the risks associated with the resume option.

  Command Re-entry
     The text of the last HISTSIZE (default 128) commands entered
     from  a  terminal  device  are  saved in memory. The in-line
     editing facility, described next, provides key mappings  for
     searching and fetching elements from the history list.

  In-line Editing
     If standard input is a terminal device,  mdb  provides  some
     simple  emacs-style facilities for editing the command line.
     The search, previous, and next commands in edit mode provide
     access  to the history list. Only strings, not patterns, are
     matched when searching. In the table below, the notation for
     control  characters  is  caret  (^)  followed by a character
     shown in upper case. The notation for escape sequences is M-
     followed  by a character. For example, M-f (pronounced meta-
     eff) is entered by depressing ESC followed  by  `f',  or  by
     depressing  Meta followed by `f' on keyboards that support a
     Meta key. A command line is  committed  and  executed  using
     RETURN or NEWLINE. The edit commands are:

     ^F
         Move cursor forward (right) one character.


     M-f
         Move cursor forward one word.


     ^B
         Move cursor backward (left) one character.


     M-b
         Move cursor backward one word.


     ^A
         Move cursor to start of line.


     ^E
         Move cursor to end of line.


     ^D
         Delete current character, if the  current  line  is  not
         empty.  If the current line is empty, ^D denotes EOF and
         the debugger exits.

     M-^H
         (Meta-backspace) Delete previous word.


     ^K
         Delete from the cursor to the end of the line.


     ^L
         Clear the screen and reprint the current line.


     ^T
         Transpose current character with next character.


     ^N
         Fetch the next command from the history. Each time ^N is
         entered, the next command forward in time is retrieved.


     ^P
         Fetch the previous command from the history.  Each  time
         ^P  is  entered,  the  next  command backward in time is
         retrieved.


     ^R[string]
         Search backward in the history for  a  previous  command
         line  containing string. The string should be terminated
         by a RETURN or NEWLINE. If string is omitted, the previ-
         ous history element containing the most recent string is
         retrieved.



     The editing mode also interprets the following  user-defined
     sequences as editing commands. User defined sequences can be
     read or modified using the stty(1) command.

     erase
         User defined erase character (usually ^H or ^?).  Delete
         previous character.


     intr
         User defined interrupt character (usually ^C). Abort the
         current command and print a new prompt.

     kill
         User defined  kill  character  (usually  ^U).  Kill  the
         entire current command line.


     quit
         User defined  quit  character  (usually  ^\).  Quit  the
         debugger.


     suspend
         User defined suspend character (usually ^Z). Suspend the
         debugger.


     werase
         User defined word erase character  (usually  ^W).  Erase
         the preceding word.



     On keyboards that support  an  extended  keypad  with  arrow
     keys, mdb interprets these keystrokes as editing commands:

     up-arrow
         Fetch the previous command from  the  history  (same  as
         ^P).


     down-arrow
         Fetch the next command from the history (same as ^N).


     left-arrow
         Move cursor backward one character (same as ^B).


     right-arrow
         Move cursor forward one character (same as ^F).


  Output Pager
     mdb provides a built-in output pager. The  output  pager  is
     enabled if the debugger's standard output is a terminal dev-
     ice. Each time a command is executed, mdb pauses  after  one
     screenful of output is produced and displays a pager prompt:

        >> More [<space>, <cr>, q, n, c, a] ?

     The following key sequences are recognized by the pager:

     SPACE
         Display the next screenful of output.


     a, A
         Abort the current top-level command and  return  to  the
         prompt.


     c, C
         Continue  displaying  output  without  pausing  at  each
         screenful  until  the  current top-level command is com-
         plete.


     n, N, NEWLINE, RETURN
         Display the next line of output.


     q, Q, ^C, ^\
         Quit (abort) the current dcmd only.


  Formatting dcmds
     The /, \, ?, and = metacharacters are  used  to  denote  the
     special output formatting dcmds. Each of these dcmds accepts
     an argument list consisting of one or  more  format  charac-
     ters,  repeat  counts, or quoted strings. A format character
     is one of the ASCII characters shown  in  the  table  below.
     Format  characters are used to read and format data from the
     target. A repeat count is a positive integer  preceding  the
     format  character  that  is  always  interpreted  in base 10
     (decimal). A repeat  count  can  also  be  specified  as  an
     expression  enclosed in square brackets preceded by a dollar
     sign ($[ ]). A string argument must be enclosed  in  double-
     quotes  ("  "). No blanks are necessary between format argu-
     ments.


     The formatting dcmds are:

     /
         Display data from the  target's  virtual  address  space
         starting at the virtual address specified by dot.

     \
         Display data from the target's  physical  address  space
         starting at the physical address specified by dot.


     ?
         Display data  from  the  target's  primary  object  file
         starting  at  the  object file location corresponding to
         the virtual address specified by dot.


     =
         Display the value of dot itself in each of the specified
         data  formats.  The  = dcmd is therefore useful for con-
         verting between bases and performing arithmetic.


     #
         Display the human readable byte count (8 bytes).



     In addition to dot, mdb keeps track of another global  value
     called  the increment. The increment represents the distance
     between dot and the address following all the data  read  by
     the  last formatting dcmd. For example, if a formatting dcmd
     is executed with dot equal to address A, and displays  a  4-
     byte  integer,  then after this dcmd completes, dot is still
     A, but the increment is set to 4. The + character (described
     under  Arithmetic Expansion above) would now evaluate to the
     value A + 4, and could be used to reset dot to  the  address
     of the next data object for a subsequent dcmd.


     Most format characters increase the value of  the  increment
     by the number of bytes corresponding to the size of the data
     format, shown in the table. The table of  format  characters
     can  be  displayed from within mdb using the ::formats dcmd.
     The format characters are:



     tab(); lw(.69i) lw(4.81i) lw(.69i) lw(4.81i)  +T{  increment
     dot by the count (variable size) T} -T{ decrement dot by the
     count (variable size) T} Bhexadecimal int (1 byte) CT{ char-
     acter using C character notation (1 byte) T} Ddecimal signed
     int (4 bytes) Edecimal unsigned long long (8 bytes)  Fdouble
     (8  bytes)  Goctal  unsigned long long (8 bytes) Hswap bytes
     and shorts (4 bytes) IT{ address and  disassembled  instruc-
     tion  (variable  size)  T}  Jhexadecimal long long (8 bytes)

     Khexadecimal  uintptr_t  (4  or  8  bytes)  Nnewline  Ooctal
     unsigned  int (4 bytes) Psymbol (4 or 8 bytes) Qoctal signed
     int (4 bytes) Rbinary int  (8  bytes)  ST{  string  using  C
     string  notation (variable size) T} Thorizontal tab Udecimal
     unsigned int  (4  bytes)  Vdecimal  unsigned  int  (1  byte)
     Wdefault  radix  unsigned  int (4 bytes) Xhexadecimal int (4
     bytes) Ydecoded time32_t (4 bytes) Zhexadecimal long long (8
     bytes)  ^T{  decrement  dot  by  increment * count (variable
     size) T} adot as symbol+offset boctal unsigned int (1  byte)
     ccharacter (1 byte) ddecimal signed short (2 bytes) edecimal
     signed long long (8 bytes) ffloat (4  bytes)  goctal  signed
     long  long  (8  bytes)  hswap  bytes (2 bytes) idisassembled
     instruction (variable size) nnewline ooctal  unsigned  short
     (2  bytes)  psymbol  (4  or  8 bytes) qoctal signed short (2
     bytes) rwhitespace sraw string (variable  size)  thorizontal
     tab udecimal unsigned short (2 bytes) vdecimal signed int (1
     byte) wdefault radix unsigned short (2  bytes)  xhexadecimal
     short (2 bytes) ydecoded time64_t (8 bytes)



     The /, \, and ? formatting dcmds can also be used  to  write
     to  the  target's  virtual  address  space, physical address
     space, or object file by specifying  one  of  the  following
     modifiers as the first format character, and then specifying
     a list of words that are either immediate values or  expres-
     sions  enclosed in square brackets preceded by a dollar sign
     ($[ ]).


     The write modifiers are:

     v
         Write the lowest byte of the value of each expression to
         the target beginning at the location specified by dot.


     w
         Write the lowest two bytes of the value of each  expres-
         sion  to  the target beginning at the location specified
         by dot.


     W
         Write the lowest 4 bytes of the value of each expression
         to  the  target  beginning  at the location specified by
         dot.

     Z
         Write the complete 8 bytes of the value of each  expres-
         sion  to  the target beginning at the location specified
         by dot.



     The /, \, and ? formatting dcmds can also be used to  search
     for  a  particular  integer  value  in  the target's virtual
     address space, physical  address  space,  and  object  file,
     respectively,  by  specifying one of the following modifiers
     as the first format character, and then specifying  a  value
     and  optional mask. The value and mask are each specified as
     either immediate values or expressions  enclosed  in  square
     brackets  preceded  by  a  dollar  sign.  If only a value is
     specified, mdb reads integers of the  appropriate  size  and
     stops  at  the  address  containing the matching value. If a
     value V and mask M are specified, mdb reads integers of  the
     appropriate size and stops at the address containing a value
     X where (X & M) == V. At the completion of the dcmd, dot  is
     updated  to the address containing the match. If no match is
     found, dot is left at the last address that was read.


     The search modifiers are:



     tab(); lw(.69i) lw(4.81i) lw(.69i) lw(4.81i) lSearch for the
     specified  2-byte  value.   LSearch for the specified 4-byte
     value.  MSearch for the specified 8-byte value.



     Notice that for both user and  kernel  targets,  an  address
     space  is  typically composed of a set of discontiguous seg-
     ments. It is not legal to read from an address that does not
     have  a corresponding segment. If a search reaches a segment
     boundary without finding a match, it aborts  when  the  read
     past the end of the segment boundary fails.

  Execution Control
     mdb provides facilities for controlling and tracing the exe-
     cution  of  a live running program. Currently, only the user
     process target provides support for execution  control.  mdb
     provides  a simple model of execution control: a target pro-
     cess can be started from within the debugger using ::run, or
     mdb can attach to an existing process using :A, ::attach, or
     the -p command-line option, as described below.  A  list  of
     traced  software  events  can be specified by the user. Each
     time a traced  event  occurs  in  the  target  process,  all
     threads  in  the  target stop, the thread that triggered the
     event is chosen as the representative  thread,  and  control
     returns to the debugger. Once the target program is set run-
     ning, control can be asynchronously returned to the debugger
     by  typing  the  user-defined interrupt character (typically
     ^C).


     A software event is a state transition in the target program
     that  is observed by the debugger. For example, the debugger
     can observe the transition of a program counter register  to
     a value of interest (a breakpoint) or the delivery of a par-
     ticular signal.


     A software event specifier is a description of  a  class  of
     software  events  that is used by the debugger to instrument
     the target program in order to  observe  these  events.  The
     ::events dcmd is used to list the software event specifiers.
     A set of standard properties is associated with  each  event
     specifier, as described under ::events, below.


     The debugger can observe a  variety  of  different  software
     events, including breakpoints, watchpoints, signals, machine
     faults, and system calls.  New  specifiers  can  be  created
     using ::bp, ::fltbp, ::sigbp, ::sysbp, or ::wp. Each specif-
     ier has an associated callback (an  mdb  command  string  to
     execute as if it had been typed at the command prompt) and a
     set of properties, as described below. Any number of specif-
     iers  for the same event can be created, each with different
     callbacks and properties. The current list of traced  events
     and the properties of the corresponding event specifiers can
     be displayed using the ::events dcmd.  The  event  specifier
     properties  are  defined  as  part of the description of the
     ::events and ::evset dcmds, below.


     The execution control built-in dcmds, described  below,  are
     always  available,  but  issues  an error message indicating
     they are not supported if applied to a target that does  not
     support  execution  control.  For more information about the
     interaction of exec, attach, release, and job  control  with
     debugger execution control, refer to NOTES, below.

  Event Callbacks
     The ::evset dcmd and event tracing dcmds allow you to  asso-
     ciate  an  event  callback  (using  the -c option) with each
     event  specifier.  The  event  callbacks  are  strings  that
     represent  mdb  commands  to  execute when the corresponding
     event occurs in the target. These commands are  executed  as
     if they had been typed at the command prompt. Before execut-
     ing each callback, the dot variable is set to the  value  of
     the  representative  thread's program counter and the "hits"
     variable is set to the number of times  this  specifier  has
     been matched, including the current match.


     If the event callbacks themselves contain one or  more  com-
     mands  to  continue  the  target  (for  example,  ::cont  or
     ::step), these commands do not immediately continue the tar-
     get  and  wait  for  it to stop again. Instead, inside of an
     event callback, the continue  dcmds  note  that  a  continue
     operation  is  now  pending,  and  then  return immediately.
     Therefore, if multiple dcmds are included in an event  call-
     back,  the  step or continue dcmd should be the last command
     specified. Following the execution of all  event  callbacks,
     the  target  immediately  resumes  execution if all matching
     event callbacks requested a continue.  If  conflicting  con-
     tinue  operations  are  requested,  the  operation  with the
     highest precedence determines what type of continue  occurs.
     The  order  of  precedence  from highest to lowest is: step,
     step-over (next), step-out, continue.

  Thread Support
     mdb provides facilities to examine the stacks and  registers
     of  each  thread  associated with the target. The persistent
     "thread" variable contains the current representative thread
     identifier.  The  format of the thread identifier depends on
     the target. The ::regs and ::fpregs dcmds  can  be  used  to
     examine the register set of the representative thread, or of
     another thread if its register set is  currently  available.
     In  addition,  the register set of the representative thread
     is exported as a set of named variables. The user can modify
     the value of one or more registers by applying the > dcmd to
     the corresponding named variable.


     The mdb kernel target exports the  virtual  address  of  the
     corresponding  internal  thread  structure as the identifier
     for a given thread.  The  Oracle  Solaris  Modular  Debugger
     Guide  provides  more  information  on debugging support for
     threads in the Solaris kernel. The mdb process  target  pro-
     vides  proper support for examination of multi-threaded user
     processes   that   use   the   native   lwp_*    interfaces,
     /usr/lib/libthread.so   or  /usr/lib/lwp/libthread.so.  When
     debugging a live user  process,  mdb  detects  if  a  single
     threaded  process  dlopens or closes libthread and automati-
     cally adjusts its view of the  threading  model  on-the-fly.
     The  process target thread identifiers corresponds to either
     the lwpid_t,  thread_t, or pthread_t of the  representative,
     depending on the threading model used by the application.

     If mdb is debugging a user process  target  and  the  target
     makes  use  of  compiler-supported thread-local storage, mdb
     automatically evaluates symbol names  referring  to  thread-
     local storage to the address of the storage corresponding to
     the current representative thread. The ::tls  built-in  dcmd
     can  be  used to display the value of the symbol for threads
     other than the representative thread.

  Built-in dcmds
     mdb provides  a  set  of  built-in  dcmds  that  are  always
     defined.  Some of these dcmds are only applicable to certain
     targets: if a dcmd is not applicable to the current  target,
     it  fails  and  prints  a message indicating "command is not
     supported by current target". In many cases, mdb provides  a
     mnemonic  equivalent  (::identifier)  for  the legacy adb(1)
     dcmd  names.  For  example,  ::quit  is  provided   as   the
     equivalent  of  $q.  Programmers  who  are  experienced with
     adb(1) or who appreciate brevity or arcana can prefer the  $
     or  : forms of the built-ins. Programmers who are new to mdb
     might prefer the more verbose ::  form.  The  built-ins  are
     shown  in alphabetical order. If a $ or : form has a ::iden-
     tifier equivalent, it is shown underneath  the  ::identifier
     form. The built-in dcmds are:

     > variable-name
     >/modifier/variable-name
         Assign the value of dot to the specified named variable.
         Some variables are read-only and can not be modified. If
         the > is followed by a modifier character surrounded  by
         /  /,  then the value is modified as part of the assign-
         ment. The modifier characters are:

         c
             unsigned char quantity (1-byte)


         s
             unsigned short quantity (2-byte)


         i
             unsigned int quantity (4-byte)


         l
             unsigned long quantity (4-byte in 32-bit, 8-byte  in
             64-bit)

         Notice that these  operators  do  not  perform  a  cast.
         Instead,  they  fetch  the specified number of low-order
         bytes (on  little-endian  architectures)  or  high-order
         bytes (big-endian architectures). Modifiers are provided
         for backwards compatibility;  the  mdb  */modifier/  and
         %/modifier/ syntax should be used instead.


     $< macro-name
         Read and execute commands from the specified macro file.
         The  filename  can  be  given as an absolute or relative
         path. If the filename is a simple name (that is,  if  it
         does  not  contain  a  `/'),  mdb searches for it in the
         macro file  include  path.  If  another  macro  file  is
         currently  being  processed,  this  file  is  closed and
         replaced with the new file.


     $<< macro-name
         Read and execute commands from the specified macro  file
         (as  with  $<),  but do not close the current open macro
         file.


     $?
         Print the process-ID and current signal of the target if
         it  is  a  user process or core file, and then print the
         general register set of the representative thread.


     [ address ] $C [ count ]
         Print a C stack backtrace, including stack frame pointer
         information.  If  the  dcmd  is  preceded by an explicit
         address, a backtrace beginning at  this  virtual  memory
         address   is  displayed.  Otherwise  the  stack  of  the
         representative thread is displayed. If an optional count
         value  is given as an argument, no more than count argu-
         ments are displayed for each stack frame in the output.


     [ base ] $d
         Get or set the default output radix. If the dcmd is pre-
         ceded  by  an  explicit  expression,  the default output
         radix is set to the given base;  otherwise  the  current
         radix is printed in base 10 (decimal). The default radix
         is base 16 (hexadecimal).


     $e
         Print a list of all known external (global)  symbols  of
         type  object  or  function, the value of the symbol, and
         the first 4 (32-bit mdb) or 8 (64-bit mdb) bytes  stored
         at  this location in the target's virtual address space.
         The  ::nm  dcmd  provides  more  flexible  options   for
         displaying symbol tables.


     $P prompt-string
         Set the  prompt  to  the  specified  prompt-string.  The
         default prompt is `> `. The prompt can also be set using
         ::set -P or the -P command-line option.


     distance $s
         Get or set the symbol matching distance for  address-to-
         symbol-name  conversions.  The  symbol matching distance
         modes are  discussed  along  with  the  -s  command-line
         option  under  OPTIONS. The symbol matching distance can
         also be modified using the ::set -s option. If  no  dis-
         tance is specified, the current setting is displayed.


     $v
         Print a list of the named variables that  have  non-zero
         values. The ::vars dcmd provides other options for list-
         ing variables.


     width $w
         Set the output page width to the specified value.  Typi-
         cally,  this command is not necessary as mdb queries the
         terminal for its width and handles resize events.


     $W
         Re-open the target for writing, as if mdb had been  exe-
         cuted with the -w option on the command line. Write mode
         can also be enabled with the ::set -w option.


     [ pid ] ::attach [ core | pid ]
     [ pid ] :A [ core | pid ]
         If the user process target  is  active,  attach  to  and
         debug  the  specified  process-ID or core file. The core
         file pathname should be specified as a string  argument.
         The  process-ID can be specified as the string argument,
         or as the value of the expression  preceding  the  dcmd.
         Recall  that the default base is hexadecimal, so decimal
         PIDs obtained using pgrep(1) or ps(1) should be preceded
         with "0t" when specified as expressions.

     [address] ::bp [-/-dDesT] [-c cmd] [-n count] sym ...
     address :b [cmd ...]
         Set a breakpoint at the specified  locations.  The  ::bp
         dcmd  sets a breakpoint at each address or symbol speci-
         fied, including an  optional  address  specified  by  an
         explicit  expression preceding the dcmd, and each string
         or immediate value following the dcmd. The arguments can
         either  be  symbol  names or immediate values denoting a
         particular virtual address of interest. If a symbol name
         is  specified,  it can refer to a symbol that cannot yet
         be evaluated in the target process. That is, it can con-
         sist  of  an  object  name  and  function name in a load
         object that has not yet been opened. In this  case,  the
         breakpoint  is  deferred and is not active in the target
         until an object matching the given name is  loaded.  The
         breakpoint is automatically enabled when the load object
         is opened. Breakpoints on symbols defined  in  a  shared
         library should always be set using a symbol name and not
         using an address expression, as the address can refer to
         the  corresponding  Procedure  Linkage Table (PLT) entry
         instead of the actual symbol definition. Breakpoints set
         on  PLT entries can be overwritten by the run-time link-
         editor when the PLT entry is  subsequently  resolved  to
         the  actual  symbol  definition. The -d, -D, -e, -s, -t,
         -T, -c, and -n options have the same meaning as they  do
         for the ::evset dcmd, as described below. If the :b form
         of the dcmd is used, a breakpoint is  only  set  at  the
         virtual  address  specified  by the expression preceding
         the dcmd. The arguments following the :b dcmd  are  con-
         catenated  together to form the callback string. If this
         string contains meta-characters, it must be quoted.


     ::cat [ -v variable-name ] filename ...
         Concatenate and display  files.  Each  filename  can  be
         specified  as  a relative or absolute pathname. The file
         contents are printed to standard  output,  but  are  not
         passed  to the output pager. This dcmd is intended to be
         used with the | operator; the programmer can initiate  a
         pipeline using a list of addresses stored in an external
         file.

         If the optional variable-name is specified,  the  speci-
         fied variable is assigned the value returned.


     ::cont [ SIG ]
     :c [ SIG ]
         Suspend the debugger, continue the target  program,  and
         wait  for  it  to terminate or stop following a software
         event of interest. If  the  target  is  already  running
         because  the  debugger was attached to a running program
         with the -o nostop  option  enabled,  this  dcmd  simply
         waits for the target to terminate or stop after an event
         of interest. If an optional signal name or  number  (see
         signal.h(3HEAD)) is specified as an argument, the signal
         is immediately delivered to the target as part of resum-
         ing  its execution. If the SIGINT signal is traced, con-
         trol can be asynchronously returned to the  debugger  by
         typing  the  user-defined  interrupt  character (usually
         ^C). This SIGINT signal is automatically cleared and  is
         not  observed  by the target the next time it is contin-
         ued. If no target program is currently  running,  ::cont
         starts a new program running as if by ::run.


     address ::context
     address $p
         Context switch  to  the  specified  process.  A  context
         switch  operation  is  only  valid when using the kernel
         target. The  process  context  is  specified  using  the
         address  of  its  proc structure in the kernel's virtual
         address space. The special context address "0"  is  used
         to denote the context of the kernel itself. mdb can only
         perform a context switch when examining a crash dump  if
         the  dump  contains  the  physical  memory  pages of the
         specified  user  process  (as  opposed  to  just  kernel
         pages). The kernel crash dump facility can be configured
         to dump all pages or the pages of the current user  pro-
         cess using dumpadm(1M). The ::status dcmd can be used to
         display the contents of the current crash dump.

         When the user requests a context switch from the  kernel
         target,  mdb  constructs  a  new target representing the
         specified user process. Once the switch occurs, the  new
         target  interposes  its  dcmds at the global level: thus
         the / dcmd now formats and displays data from  the  vir-
         tual  address  space of the user process, the ::mappings
         dcmd displays the mappings in the address space  of  the
         user  process,  and  so  on.  The  kernel  target can be
         restored by executing 0::context.


     ::dcmds
         List the available dcmds and print a  brief  description
         for each one.


     ::sort [-u [-c][-v var]] [type] [-s [-i]][-r] [at]
     offset|member [[-s [-i]][-r][-u] member]... [|::dcmd ...]
         Sort the addresses based on the  rules  given.  With  no
         arguments  ::sort sorts the address based on its numeric
         values. If a type is given then ::sort  sorts  based  on
         the  member of structure or union given. If an offset is
         given then the sort is based on the value of the  simple
         type  at that value. Multiple sort keys can be given and
         each sort key can have its own  options.  See  SORT  KEY
         OPTIONS.

         SIMPLE TYPES

         char, uchar, short,  ushort,  int,  uint,  long,  ulong,
         longlong, ulonglong, pointer, addr

         OPTIONS

         -u
               Uniq. Only prints addresses that  match  according
               to the sort criteria once.


         -R
               Not  uniq.  Suppresses  lines  that  do  not  have
               matches according to the sort.


         -U
               Really uniq. Only prints entries that  are  unique
               according to the sort.


         -c
               If not outputting to a pipe  and  using  the  uniq
               flag  then  print  a  count of matches before each
               address.


         -v
               Stores the count of  unique  entries  in  variable
               var.

         SORT KEY OPTIONS

         -r
                   Reverse the order of this test.


         -s
                   Treat this item as a string.


         -i
                   If sorting strings ignore case.


         -u
                   Uniq for this key. Sort  using  the  remaining
                   keys  but  only  output  the  last  entry that
                   matches on this key. See ::help sort for exam-
                   ples.

         -l len
                   If sorting pointers  dereference  the  pointer
                   and compare len bytes.



     [ address ] ::delete [ id | all ]
     [ address ] :d [ id | all ]
         Delete the event specifiers with the  given  id  number.
         The  id  number  argument  is  interpreted in decimal by
         default. If an optional address is  specified  preceding
         the  dcmd, all event specifiers that are associated with
         the given virtual address are deleted (for example,  all
         breakpoints  or  watchpoints affecting that address). If
         the special argument "all" is given, all  event  specif-
         iers are deleted, except those that are marked sticky (T
         flag). The ::events dcmd displays the  current  list  of
         event specifiers.


     [ address ] ::dis [ -fw ] [ -n count ] [ address ]
         Disassemble starting at or around the address  specified
         by  the  final argument, or the current value of dot. If
         the address matches the start of a known  function,  the
         entire  function  is disassembled. Otherwise, a "window"
         of instructions before and after the  specified  address
         is  printed  in  order  to  provide context. By default,
         instructions are read from the target's virtual  address
         space.  If  the  -f  option is present, instructions are
         read from the  target's  object  file  instead.  The  -f
         option  is  enabled  by  default  if the debugger is not
         currently attached to a  live  process,  core  file,  or
         crash   dump.  The  -w  option  can  be  used  to  force
         "window"-mode, even if the address is  the  start  of  a
         known  function.  The size of the window defaults to ten
         instructions; the number of instructions can  be  speci-
         fied explicitly using the -n option.


     ::disasms
         List the available disassembler modes. When a target  is
         initialized,  mdb  attempts  to  select  the appropriate
         disassembler mode. The user can change the mode  to  any
         of the modes listed using the ::dismode dcmd.


     ::dismode [ mode ]
     $V [ mode ]
         Get or set the disassembler  mode.  If  no  argument  is
         specified,  print  the  current  disassembler mode. If a
         mode argument is specified, switch the  disassembler  to
         the  specified mode. The list of available disassemblers
         can be displayed using the ::disasms dcmd.


     ::dmods [ -l ] [ module-name ]
         List the loaded debugger modules. If the  -l  option  is
         specified,  the list of the dcmds and walkers associated
         with each dmod is printed below its name. The output can
         be  restricted  to  a  particular dmod by specifying its
         name as an additional argument.


     [ address ] ::dump [ -eqrstu ] [ -f|-p ]
     [ -g bytes ] [ -w paragraphs ]
         Print a hexadecimal and ASCII memory dump of the 16-byte
         aligned  region  of memory containing the address speci-
         fied by dot. If a repeat count is specified for  ::dump,
         this  is interpreted as a number of bytes to dump rather
         than a number of iterations. The ::dump dcmd also recog-
         nizes the following options:

         -e
             Adjusts for endian-ness. The -e  option  assumes  4-
             byte  words. The -g option can be used to change the
             default word size.


         -f
             Reads data from the object file location correspond-
             ing to the given virtual address instead of from the
             target's virtual address space.  The  -f  option  is
             enabled  by default if the debugger is not currently
             attached to a live  process,  core  file,  or  crash
             dump.


         -g bytes
             Displays bytes in groups of bytes. The default group
             size  is  4 bytes. The group size must be a power of
             two that divides the line width.


         -p
             Interprets address as a physical address location in
             the  target's  address  space  instead  of a virtual
             address.

         -q
             Does not print an ASCII decoding of the data.


         -r
             Numbers lines relative to the start address  instead
             of  with  the  explicit  address  of each line. This
             option implies the -u option.


         -s
             Elides repeated lines.


         -t
             Only reads from and displays  the  contents  of  the
             specified addresses, instead of reading and printing
             entire lines.


         -u
             Unaligns output instead of aligning the output at  a
             paragraph boundary.


         -w paragraphs
             Displays paragraphs at 16-byte paragraphs per  line.
             The default number of paragraphs is one. The maximum
             value accepted for -w is 16.



     ::echo [ string | value ...]
         Print the arguments separated by blanks  and  terminated
         by a NEWLINE to standard output. Expressions enclosed in
         $[ ] is evaluated to a value and printed in the  default
         base.


     ::eval command
         Evaluate and execute the specified string as a  command.
         If the command contains metacharacters or whitespace, it
         should be enclosed in double or single quotes.


     ::events [ -av ]
     $b [ -av ]
         Display the list  of  software  event  specifiers.  Each
         event  specifier is assigned a unique ID number that can
         be used to delete or modify it  at  a  later  time.  The
         debugger  can  also have its own internal events enabled
         for tracing. These events are only be displayed  if  the
         -a  option  is  present.  If the -v option is present, a
         more verbose  display,  including  the  reason  for  any
         specifier  inactivity,  are  shown.  Here is some sample
         output:

           > ::events
              ID S TA HT LM Description                      Action
           ----- - -- -- -- -------------------------------- ------
           [ 1 ] - T   1  0 stop on SIGINT                   -
           [ 2 ] - T   0  0 stop on SIGQUIT                  -
           [ 3 ] - T   0  0 stop on SIGILL                   -
            ...
           [ 11] - T   0  0 stop on SIGXCPU                  -
           [ 12] - T   0  0 stop on SIGXFSZ                  -
           [ 13] -     2  0 stop at libc`printf              ::echo printf
           >


         The following table explains the meaning of each column.
         A  summary of this information is available using ::help
         events.

         ID
             The event specifier identifier.  The  identifier  is
             shown  in  square  brackets  [ ] if the specifier is
             enabled, in parentheses ( ) if the specifier is dis-
             abled,  or  in angle brackets < > if the target pro-
             gram is currently stopped on an event  that  matches
             the given specifier.


         S
             The event specifier state. The state is one  of  the
             following symbols:

             -
                 The event specifier is idle. When no target pro-
                 gram  is  running, all specifiers are idle. When
                 the target program is running, a  specifier  can
                 be  idle if it cannot be evaluated (for example,
                 a deferred breakpoint in a shared object that is
                 not yet loaded).


             +
                 The event specifier is active. When  the  target
                 is continued, events of this type is detected by
                 the debugger.


             *
                 The event specifier is armed. This  state  means
                 that   the  target  is  currently  running  with
                 instrumentation for this  type  of  event.  This
                 state   is  only  visible  if  the  debugger  is
                 attached to a running program with the -o nostop
                 option.


             !
                 The event specifier was  not  armed  due  to  an
                 operating  system  error. The ::events -v option
                 can be used to display  more  information  about
                 the reason the instrumentation failed.



         TA
             The Temporary, Sticky, and Automatic event specifier
             properties. One or more of the following symbols can
             be shown:

             t
                 The event specifier is temporary, and is deleted
                 the  next  time  the target stops, regardless of
                 whether it is matched.


             T
                 The event specifier is sticky,  and  is  not  be
                 deleted by ::delete all or :z. The specifier can
                 be  deleted  by  explicitly  specifying  its  id
                 number to ::delete.


             d
                 The event specifier  is  automatically  disabled
                 when the hit count is equal to the hit limit.


             D
                 The event  specifier  is  automatically  deleted
                 when the hit count is equal to the hit limit.

             s
                 The target  automatically  stops  when  the  hit
                 count is equal to the hit limit.



         HT
             The current hit  count.  This  column  displays  the
             number of times the corresponding software event has
             occurred in the target since the  creation  of  this
             event specifier.


         LM
             The current hit  limit.  This  column  displays  the
             limit  on  the  hit count at which the auto-disable,
             auto-delete, or  auto-stop  behavior  takes  effect.
             These  behaviors can be configured using the ::evset
             dcmd, described below.


         Description
             A description of the type of software event that  is
             matched by the given specifier.


         Action
             The callback string to execute when the  correspond-
             ing software event occurs. This callback is executed
             as if it had been typed at the command prompt.



     [id] ::evset [-/-dDestT] [-c cmd] [-n count] id ...
         Modify the properties of  one  or  more  software  event
         specifiers.  The  properties  are set for each specifier
         identified by the optional expression preceding the dcmd
         and  an  optional  list of arguments following the dcmd.
         The argument list is interpreted as a  list  of  decimal
         integers,  unless  an  explicit  radix is specified. The
         ::evset dcmd recognizes the following options:

         -d
             Disables the event  specifier  when  the  hit  count
             reaches  the hit limit. If the -d form of the option
             is given, this behavior is disabled. Once  an  event
             specifier  is  disabled,  the  debugger  removes any
             corresponding  instrumentation   and   ignores   the
             corresponding software events until the specifier is
             subsequently re-enabled. If the  -n  option  is  not
             present, the specifier is disabled immediately.


         -D
             Deletes the  event  specifier  when  the  hit  count
             reaches  the hit limit. If the -D form of the option
             is given, this behavior is disabled. The  -D  option
             takes  precedence  over the -d option. The hit limit
             can be configured using the -n option.


         -e
             Enables the event specifier. If the -e form  of  the
             option is given, the specifier is disabled.


         -s
             Stops the target program when the hit count  reaches
             the  hit  limit.  If  the  -s  form of the option is
             given, this behavior is disabled.  The  -s  behavior
             tells  the  debugger  to  act  as if the ::cont were
             issued following each execution of  the  specifier's
             callback,  except  for the Nth execution, where N is
             the current value of the specifier's hit limit.  The
             -s  option  takes precedence over both the -D option
             and the -d option.


         -t
             Marks the event specifier  as  temporary.  Temporary
             specifiers  are  automatically deleted the next time
             the target stops, regardless of whether  it  stopped
             as  the  result of a software event corresponding to
             the given specifier. If the -t form of the option is
             given,  the  temporary  marker  is  removed.  The -t
             option takes precedence over the -T option.


         -T
             Marks the event specifier as sticky. Sticky  specif-
             iers are not deleted by ::delete all or :z. They can
             be deleted by specifying the corresponding specifier
             ID  as  an  explicit argument to ::delete. If the -T
             form of the option is given, the sticky property  is
             removed. The default set of event specifiers are all
             initially marked sticky.

         -c
             Executes the specified  cmd  string  each  time  the
             corresponding  software  event  occurs in the target
             program.  The  current  callback   string   can   be
             displayed using ::events.


         -n
             Sets the current value of the hit limit to count. If
             no hit limit is currently set and the -n option does
             not accompany -s or D, the hit limit is set to one.

         A summary of this information is available using  ::help
         evset.


     ::files
     $f
         Print a list of the known source files (symbols of  type
         STT_FILE present in the various target symbol tables).


     [flt] ::fltbp [-/-dDestT] [-c cmd] [-n count] flt ...
         Trace the specified machine faults. The faults are iden-
         tified  using  an  optional  fault  number preceding the
         dcmd,  or  a  list  of  fault  names  or  numbers   (see
         <sys/fault.h>)  following  the dcmd. The -d, -D, -e, -s,
         -t, -T, -c, and -n options have the same meaning as they
         do for the ::evset dcmd.


     [ thread ] ::fpregs
     [ thread ] $x, $X, $y, $Y
         Print the floating-point register set of the representa-
         tive  thread.  If  a  thread  is specified, the floating
         point registers of that thread are displayed. The thread
         expression  should  be  one  of  the  thread identifiers
         described under Thread Support, above.


     ::formats
         List the available output format characters for use with
         the  /,  \,  ?,  and = formatting dcmds. The formats and
         their use is described under Formatting dcmds, above.


     ::grep command
         Evaluate the specified command string,  and  then  print
         the  old  value  of  dot if the new value of dot is non-
         zero. If the command contains whitespace or  metacharac-
         ters,  it must be quoted. The ::grep dcmd can be used in
         pipelines to filter a list of addresses.


     ::help [ dcmd-name ]
         With no arguments, the ::help dcmd prints a brief  over-
         view  of  the  help  facilities  available  in mdb. If a
         dcmd-name is specified, mdb prints a usage  summary  for
         that dcmd.


     signal :i
         If the target is a live user process, ignore the  speci-
         fied  signal  and allow it to be delivered transparently
         to the target. All event  specifiers  that  are  tracing
         delivery  of  the  specified  signal is deleted from the
         list of traced events. By default, the  set  of  ignored
         signals  is  initialized to the complement of the set of
         signals that cause a process to  dump  core  by  default
         (see  signal.h(3HEAD)),  except  for  SIGINT,  which  is
         traced by default.


     $i
         Display the list of signals  that  are  ignored  by  the
         debugger  and  that  is  handled directly by the target.
         More information on traced signals can be obtained using
         the ::events dcmd.


     [ address ] ::if [-p] {type member tests | [type] [at off]
     test}
         Evaluate the tests and then print the old value  of  dot
         if the tests are true.

         -p
             Use physical rather than virtual addresses.

         There are two kinds of tests. The first  allows  you  to
         test  the value of a member of a structure or union. The
         second allows you to test  an  offset  from  dot.  These
         tests  can  then  be joined with AND or OR to build more
         complex tests.

         Start with an example of testing a member  of  a  struc-
         ture:

           ::if "struct foo" namep <> 0

         This statement would print the old value of dot  if  the
         element namep in structure foo were not 0.

           ::if "struct foo" namep <> 0 AND namep->name <> 0 AND
           namep->name streq "bar"


         The preceding statement would print the old value of dot
         if the element  name in structure pointed to by namep in
         foo were not 0 and pointed to a  string  that  contained
         the string bar.

           ::if "struct foo" name <> 0 AND name streq "bar" and value = 0x123


         The preceding statement would print  only  if  the  name
         were bar and value was 0x123.

         The second form tests to see if the type  at  the  given
         offset has the given value. Here is an example:

           ::if uint_t at 0x34 = 0x123


         This will print if the value of an uint_t at offset 0x34
         is  0x123.   Again  this  can be joined with other tests
         using AND or OR. With this form, ::if has  a  number  of
         built-in  types  that are internal that can be used even
         when there is no symbolic type information. These  types
         are:

           char, uchar, short, ushort, int, uint, long, ulong,
           longlong, ulonglong, pointer, addr


         If the type is addr, then, rather than the value at that
         address,  the  actual  address is tested. So, the state-
         ment:

           ::if addr at 0x34 = 0x100034


         ...would report the value of dot only  if  dot+0x34  was
         0x100034, whereas:

           ::if pointer at 0x34 = 0x100034


         ...would print only if the value at dot+0x34.

         More usefully, the statement:

           ::if "char *' at 0x34 streq "foo"


         ...will print the old value of dot if the string pointed
         to at offset 0x34 is foo.

         Possible tests are:

           =          -   True if   the values are equal.
           <>        -    True if   the values are not equal.
           <          -   True if   the value is less than the right hand value.
           <=        -    True if   the value is less than or equal to the right hand value.
           >          -   True if   the value is greater than the right hand value.
           >=        -    True if   the value is greater than or equal to the right hand value.
           &          -   True if   the values ANDed together are non zero.
           ^          -   True if   the values XORed together are non zero.
           streq      -   True if   the strings exactly match.
           strneq     -   True if   the strings don't match.
           strcaseeq  -   True if   the strings match case insensitively.
           strncaseeq -   True if   the strings do not match case insensitively.
           strleneq   -   True if   the string is this length.
           strlenneq  -   True if   the string is not this length.
           strlengt   -   True if   the string is longer than this.
           strlenlt   -   True if   the string is shorter than this.
           strlenge   -   True if   the string is this long  or longer.
           strlenle   -   True if   the string is this long  or shorter


         streq accepts the following options:

         -i
                      Test ignoring the case.


         -n
                      Return true if there is no match.


         -o offset
                      Start search at offset into string.


         -s
                      Search for a substring.

         strstr accepts the following options:

         -i
                        Test ignoring the case.


         -n
                        Return true if there is no match.


         -v variable
                        Store the address of the found string  in
                        variable.

         regex accepts the following options:

         -i
                        Test ignoring the case.


         -n
                        Return true if there is no match.


         -v variable
                        Store the address of the found string  in
                        variable.


         -x
                        Insist on an exact match.

         streq,  strneq,  strcaseeq,   strcaseneq,   strstr   and
         strcasestr accept these options:

         -s
                      Search for a substring.


         -o offset
                      Start search at offset into string.

         strstr and strcasestr accept these options:

         -v variable
                        Store the address of the found string  in
                        variable.

         The right hand side of a test can be any one of the fol-
         lowing:

             o    An element in the structure or union.

             o    The value from a symbol.

             o    An absolute value.

             o    <var - the value of the variable var.

             o    $expr - the value of dot after  mdb  expression
                  expr  is  evaluated.  This must be quoted using
                  double quotation marks (""). For example:

                    "$<var=J"


                  ...would get the value of variable var.


     ::kill
     :k
         Forcibly terminate the target if it is a live user  pro-
         cess.  The  target  is also forcibly terminated when the
         debugger exits if it was created by the  debugger  using
         ::run.


     $l
         Print the LWPID of the  representative  thread,  if  the
         target is a user process.


     $L
         Print the LWPIDs of each LWP in the target, if the  tar-
         get is a user process.


     [ address ] ::list [-b back_member][-p][-L] [type] member [
     variable-name ]
         Walk through the elements of a linked list data   struc-
         ture  and print the address of each element in the list.
         The address of the first element  in  the  list  can  be
         specified using an optional address. Otherwise, the list
         is assumed to start at the current  value  of  dot.  The
         type parameter must name a C struct or union type and is
         used to describe the type of the list elements  so  that
         mdb  can  read  in  objects  of the appropriate size. If
         ::list can determine the type then type can be  omitted.
         The  member parameter is used to name the member of type
         that contains a pointer to the next  list  element.  The
         ::list  dcmd continues iterating until a NULL pointer is
         encountered, the first element is reached again (a  cir-
         cular  list),  a loop is detection is enabled (-L) and a
         loop is detected, back member checking is  enabled  (-b)
         and  a  bad back pointer is detected, or an error occurs
         while reading an element. If the optional  variable-name
         is  specified,  the  specified  variable is assigned the
         value returned at each step of the walk when mdb invokes
         the next stage of a pipeline.

         -b back_member
             Verify  that  back_member  points  to  the  previous
             member  of the list. The first member of the list is
             allowed to have a NULL back pointer.


         -L
             Check for loops in the list. Will print  every  ele-
             ment in the list once.

         -p
             Read from physical rather than virtual addresses.

         The ::list dcmd can only be used with objects that  con-
         tain  symbolic  debugging  information  designed for use
         with mdb. Refer to NOTES, "Symbolic  Debugging  Informa-
         tion," below for more information.


     addr ::tail [+-]num|[+-]n num [|::dcmd ...]
         Prints the last elements in the pipe.

         -n num OR -num
                           Passes only the last num  elements  in
                           the pipe.


         +n num OR +num
                           Passes all except the first  num  ele-
                           ments   in   the   pipe.  (num  is  in
                           decimal).

         It has the following attributes:

         Target
                                proc


         Module
                                mdb


         Interface Stability
                                Evolving



     addr ::head [-+]num|[-+]n num [|::dcmd ...]
         Limits the number of elements in pipe.

         -n num OR -num
                           Passes only the first num elements  in
                           the pipe.


         +n num OR +num
                           Passes all except the  last  num  ele-
                           ments   in   the   pipe.  (num  is  in
                           decimal).

         It has the following attributes:

         Target
                                proc


         Module
                                mdb

         Interface Stability
                                Evolving



     ::load [ -s ] module-name
         Load the specified dmod. The module name can be given as
         an absolute or relative path. If module-name is a simple
         name (that is, does not contain a `/'), mdb searches for
         it  in the module library path. Modules with conflicting
         names can not be loaded; the  existing  module  must  be
         unloaded first. If the -s option is present, mdb remains
         silent and not issue any error messages if the module is
         not found or could not be loaded.


     ::log [ -d | [ -e ] filename ]
     $> [ filename ]
         Enable or  disable  the  output  log.  mdb  provides  an
         interactive  logging  facility where both the input com-
         mands and standard output can be logged to a file  while
         still  interacting  with the user. The -e option enables
         logging to the specified file, or re-enables logging  to
         the  previous  log  file if no filename is given. The -d
         option disables logging. If the $> dcmd is used, logging
         is  enabled  if a filename argument is specified; other-
         wise, logging is disabled. If  the  specified  log  file
         already  exists,  mdb  appends any new log output to the
         file.


     ::map command
         Map the value of dot to a corresponding value using  the
         command  specified  as a string argument, and then print
         the new value of dot. If the command contains whitespace
         or metacharacters, it must be quoted. The ::map dcmd can
         be used in pipelines to transform the list of  addresses
         into a new list of addresses.


     [ address ] ::mappings [ name ]
     [ address ] $m [ name ]
         Print a list of each mapping  in  the  target's  virtual
         address space, including the address, size, and descrip-
         tion of each mapping. If the  dcmd  is  preceded  by  an
         address,  mdb  only  shows the mapping that contains the
         given address. If a string name argument is  given,  mdb
         only shows the mapping matching that description.

     ::next [ SIG ]
     :e [ SIG ]
         Step the target program one instruction, but  step  over
         subroutine  calls.  If an optional signal name or number
         (see signal.h(3HEAD)) is specified as an  argument,  the
         signal is immediately delivered to the target as part of
         resuming  its  execution.  If  no  target   program   is
         currently  running,  ::next starts a new program running
         as if by ::run and stop at the first instruction.


     [ address ] ::nm [ -DPdghnopuvx ] [ -t types ]
     [ -f format ] [ object ]
         Print the symbol tables associated with the current tar-
         get. If an optional address preceding the dcmd is speci-
         fied,  only  the  symbol  table  entry  for  the  symbol
         corresponding  to  address is displayed. If an object is
         specified, only the symbol table for this load object is
         displayed.  The  ::nm dcmd also recognizes the following
         options:

         -D
             Prints .dynsym (dynamic  symbol  table)  instead  of
             .symtab.


         -P
             Prints the private symbol table instead of .symtab.


         -d
             Prints value and size fields in decimal.


         -g
             Prints only global symbols.


         -h
             Suppresses the header line.


         -n
             Sorts symbols by name.


         -o
             Prints value and size fields in octal.

         -p
             Prints symbols as a series of ::nmadd commands. This
             option  can  be used with -P to produce a macro file
             that can be subsequently read into the debugger with
             $<.


         -u
             Prints only undefined symbols.


         -v
             Sorts symbols by value.


         -x
             Prints value and size fields in hexadecimal.


         -t type[,type ... ]
             Prints only symbols of the  specified  type(s).  The
             valid type argument strings are:

             noty
                 STT_NOTYPE


             objt
                 STT_OBJECT


             func
                 STT_FUNC


             sect
                 STT_SECTION


             file
                 STT_FILE


             comm
                 STT_COMMON

             tls
                 STT_TLS


             regi
                 STT_SPARC_REGISTER



         -f format[,format ... ]
             Prints only the specified  symbol  information.  The
             valid format argument strings are:

             ndx
                 symbol table index


             val
                 symbol value


             size
                 size in bytes


             type
                 symbol type


             bind
                 binding


             oth
                 other


             shndx
                 section index


             name
                 symbol name

             ctype
                 C type for symbol (if known)


             obj
                 object which defines symbol




     value ::nmadd [ -fo ] [ -e end ] [ -s size ] name
         Add the specified symbol  name  to  the  private  symbol
         table. mdb provides a private, configurable symbol table
         that can be used to interpose  on  the  target's  symbol
         table,  as described under Symbol Name Resolution above.
         The ::nmadd dcmd also recognizes the following options:

         -e
             Sets the size of the symbol to end - value.


         -f
             Sets the type of the symbol to STT_FUNC.


         -o
             Sets the type of the symbol to STT_OBJECT.


         -s
             Sets the size of the symbol to size.



     ::nmdel name
         Delete the specified symbol name from the private symbol
         table.


     ::objects [ -v ]
         Print a map of the target's virtual address space, show-
         ing  only  those mappings that correspond to the primary
         mapping (usually the text section) of each of the  known
         load objects. The -v option displays the version of each
         load object. Version information is  not  available  for
         all  load objects. Load objects without version informa-
         tion is listed as having a version of "Unknown"  in  the
         output for the -v option.

     ::offsetof member
         Print the offset of the specified member of the   speci-
         fied type. The type should be the name of a C structure.
         If no member is specified all the members for this  type
         are reported.

         The offset is printed in bytes, unless the member  is  a
         bit-field,  in  which  case the offset can be printed in
         bits. The output is always suffixed with the appropriate
         units  for  clarity. The type name can use the backquote
         (`) scoping operator described under Symbol Name Resolu-
         tion,  above.  The ::offsetof dcmd can only be used with
         objects  that  contain  symbolic  debugging  information
         designed  for  use  with  mdb.  Refer to NOTES, Symbolic
         Debugging Information, below for more information.


     address ::print [ -aCdiLptx ] [ -c lim ]
     [ -l lim ] [ type [ member ... ] ]
         Print  the  data  structure  at  the  specified  virtual
         address  using  the  given  type  information.  The type
         parameter can name a C struct, union, enum,  fundamental
         integer type, or a pointer to any of these types. If the
         type name  contains  whitespace  (for  example,  "struct
         foo"),  it  must be enclosed in single or double quotes.
         The type name can use the backquote (`) scoping operator
         described  under  Symbol  Name Resolution, above. If the
         type is a structured type, the ::print dcmd  recursively
         prints  each  member of the struct or union. If the type
         argument  is  not  present  and  a  static   or   global
         STT_OBJECT  symbol  matches  the address, ::print infers
         the appropriate type automatically. If the type argument
         is  specified, it can be followed by an optional list of
         member expressions, in which case only those members and
         submembers  of the specified type are displayed. If type
         contains other structured types, each member string  can
         refer  to  a  sub-structure element by forming a list of
         member names separated by period ('.')  delimiters.  The
         ::print  dcmd can only be used with objects that contain
         symbolic debugging information  designed  for  use  with
         mdb.  Refer  to  NOTES,  Symbolic Debugging Information,
         below for more information. After  displaying  the  data
         structure, ::print increments dot by the size of type in
         bytes.

         If the -a option is present, the address of each  member
         is  displayed.  If  the  -p  option  is present, ::print
         interprets address as a physical memory address  instead
         of  a  virtual  memory  address.  If  the  -t  option is
         present, the type of each member is displayed. If the -d
         or -x options are present, all integers are displayed in
         decimal (-d) or hexadecimal (-x). By default, a  heuris-
         tic  is  used  to  determine  if  the  value  should  be
         displayed in decimal or hexadecimal. The number of char-
         acters  in  a character array that is read and displayed
         as a string can be limited with the -c option. If the -C
         option  is  present, no limit is enforced. The number of
         elements in a standard array that is read and  displayed
         can  be  limited with the -l option. If the -L option is
         present, no limit is enforced and all array elements are
         shown.  The default values for -c and -l can be modified
         using ::set or the -o command-line option  as  described
         under OPTIONS.

         If the -i option is  specified,  the  address  value  is
         interpreted  as  an  immediate  value to be printed. You
         must give a type with which to interpret the  value.  If
         the type is smaller than 64 bits, the immediate value is
         interpreted as if it were the size of the type.  The  -i
         option cannot be used in conjunction with the -p option.
         If the -a option is given, the addresses shown are  byte
         offsets starting at zero.


     ::quit
     $q
         Quit the debugger.


     [ thread ] ::regs
     [ thread ] $r
         Print the general purpose register set of the  represen-
         tative  thread.  If  a  thread is specified, the general
         purpose register set of that thread  is  displayed.  The
         thread  expression  should be one of the thread identif-
         iers described under Thread Support, above.


     ::release [ -a ]
     :R [ -a ]
         Release the previously attached process or core file. If
         the  -a  option  is present, the process is released and
         left stopped and abandoned. It can subsequently be  con-
         tinued  by prun(1) (see proc(1)) or it can be resumed by
         applying mdb or another debugger. By default, a released
         process  is forcibly terminated if it was created by mdb
         using ::run, or it is released and set running if it was
         attached  to  by  mdb  using  the -p option or using the
         ::attach or :A dcmds.

     ::run [ args . . . ]
     :r [ args . . . ]
         Start a new target program running  with  the  specified
         arguments and attach to it. The arguments are not inter-
         preted by the shell. If the debugger is already  examin-
         ing  a live running program, it first detaches from this
         program as if by ::release.


     ::set [ -wF ] [ -/-o option ] [ -s distance ] [ -I path ]
     [ -L path ] [ -P prompt ]
         Get or set  miscellaneous  debugger  properties.  If  no
         options  are specified, the current set of debugger pro-
         perties is displayed. The ::set dcmd recognizes the fol-
         lowing options:

         -F
             Forcibly takes  over  the  next  user  process  that
             ::attach  is applied to, as if mdb had been executed
             with the -F option on the command line.


         -I
             Sets the default path for locating macro files.  The
             path  argument can contain any of the special tokens
             described  for  the  -I  command-line  option  under
             OPTIONS.


         -L
             Sets the default path for locating debugger modules.
             The  path  argument  can  contain any of the special
             tokens described  for  the  -I  command-line  option
             under OPTIONS.


         -o
             Enables the specified debugger  option.  If  the  -o
             form  is  used,  the  option is disabled. The option
             strings are described along with the -o command-line
             option under OPTIONS.


         -P
             Sets the command  prompt  to  the  specified  prompt
             string.

         -s
             Sets the symbol matching distance to  the  specified
             distance.   Refer  to  the  description  of  the  -s
             command-line option under OPTIONS for more  informa-
             tion.


         -w
             Re-opens the target for writing, as if mdb had  been
             executed with the -w option on the command line.



     [address]::shell [-o b|o|d|x|s] "shell command"
         Pipe the address or addresses through the shell  command
         given  and then allow the output of the shell command to
         be piped back into the  mdb pipeline.

         If the -o option is entered, interpret the  output  from
         the shell command according to the numerical base speci-
         fied. Arguments to - o are as follows:

         b
              binary


         o
              octal


         d
              decimal


         x
              hexadecimal


         s
              treat output as a string with no interpretation

         Example:

           ::walk proc | ::shell "tail -10" | ::print proc_t




     ::showrev [ -pv ]
         Display  revision  information  for  the  hardware   and
         software.  With  no  options  specified,  general system
         information is displayed. The -v option displays version
         information  for all load objects, whereas the -p option
         displays the  version  information  only  for  the  load
         objects  that  have been installed on the system as part
         of a patch. Version information is not available for all
         load  objects.  Load objects without version information
         is omitted from the output for  the  -p  option  and  is
         listed  as  having  a version of "Unknown" in the output
         for the -v option.


     [signal] ::sigbp [-/-dDestT] [-c cmd] [-n count] SIG ...
     [signal] :t [-/-dDestT] [-c cmd] [-n count] SIG ...
         Trace delivery of the specified signals. The signals are
         identified using an optional signal number preceding the
         dcmd,  or  a  list  of  signal  names  or  numbers  (see
         signal.h(3HEAD)) following the dcmd. The -d, -D, -e, -s,
         -t, -T, -c, and -n options have the same meaning as they
         do  for  the ::evset dcmd. Initially, the set of signals
         that cause the process to  dump  core  by  default  (see
         signal.h(3HEAD)) and SIGINT are traced.


     ::sizeof [-s size] [-r min max] [type [member ...]]
         Options are as follows:

         -s size
             Show types for entries of this size.


         -r min max
             Show types for entries in range of sizes.

         Print the size of the specified type in bytes. The  type
         parameter  can name a C struct, union, enum, fundamental
         integer type, or a pointer to any of  these  types.  The
         type  name  can  use  the backquote (`) scoping operator
         described under Symbol Name  Resolution,  above.  member
         can  be specified with standard C syntax using the array
         indexing operator "[index]", structure  member  operator
         ".".

         The ::sizeof dcmd can only be  used  with  objects  that
         contain  symbolic debugging information designed for use
         with mdb. Refer to NOTES,  Symbolic  Debugging  Informa-
         tion, below for more information.


     [ address ] ::stack [ count ]
     [ address ] $c [ count ]
         Print a C stack backtrace. If the dcmd is preceded by an
         explicit  address, a backtrace beginning at this virtual
         memory address is displayed. Otherwise the stack of  the
         representative thread is displayed. If an optional count
         value is given as an argument, no more than count  argu-
         ments are displayed for each stack frame in the output.


     ::status
         Print a summary of information related  to  the  current
         target.


     ::step [ over | out ] [ SIG ]
     :s [ SIG ]
     :u [ SIG ]
         Step the target program one instruction. If an  optional
         signal name or number (see signal.h(3HEAD)) is specified
         as an argument, the signal is immediately  delivered  to
         the  target  as  part  of resuming its execution. If the
         optional "over" argument is specified, ::step steps over
         subroutine  calls.  The ::step over argument is the same
         as the ::next dcmd. If the optional  "out"  argument  is
         specified,   the  target  program  continues  until  the
         representative thread returns from the current function.
         If  no  target  program is currently running, ::step out
         starts a new program running as if by ::run and stop  at
         the  first  instruction.  The  :s  dcmd  is  the same as
         ::step. The :u dcmd is the same as ::step out.


     [ syscall ] ::sysbp [ -/-dDestT ] [ -io ] [ -c cmd ]
     [ -n count ] syscall...
         Trace entry to or exit from the specified system  calls.
         The system calls are identified using an optional system
         call number preceding the dcmd, or a list of system call
         names  or  numbers  (see  <sys/syscall.h>) following the
         dcmd. If the -i option is specified (the  default),  the
         event  specifiers  trigger  on entry into the kernel for
         each system call. If the -o  option  is  specified,  the
         event  specifiers  trigger  on exit out from the kernel.
         The -d, -D, -e, -s, -t, -T, -c, and -n options have  the
         same meaning as they do for the ::evset dcmd.


     thread ::tls symbol
         Print the address  of  the  storage  for  the  specified
         thread-local  storage (TLS) symbol in the context of the
         specified thread. The thread expression should be one of
         the  thread  identifiers described under Thread Support,
         above. The symbol name can use any of the scoping opera-
         tors described under Symbol Name Resolution, above.

     ::typeset [ -/-t] variable-name . . .
         Set attributes for named variables. If one or more vari-
         able  names  are  specified, they are defined and set to
         the value of dot. If  the  -t  option  is  present,  the
         user-defined  tag  associated with each variable is set.
         If the -t option is present, the tag is cleared.  If  no
         variable  names are specified, the list of variables and
         their values is printed.


     ::unload module-name
         Unload the specified dmod. The list of active dmods  can
         be  printed using the ::dmods dcmd. Built-in modules can
         not be unloaded. Modules that are busy (that is, provide
         dcmds that are currently executing) can not be unloaded.


     ::unset variable-name . . .
         Unset (remove) the specified variable(s) from  the  list
         of defined variables. Some variables exported by mdb are
         marked as persistent, and can not be unset by the user.


     ::vars [-npt]
         Print a listing of named variables. If the -n option  is
         present,  the  output  is  restricted  to variables that
         currently have non-zero values.  If  the  -p  option  is
         present,  the  variables  are printed in a form suitable
         for re-processing by the debugger  using  the  $<  dcmd.
         This  option  can  be  used to record the variables to a
         macro file and then restore these values later.  If  the
         -t  option  is  present,  only  the tagged variables are
         printed. Variables can be tagged using the -t option  of
         the ::typeset dcmd.


     ::version
         Print the debugger version number.


     address ::vtop [-a as]
         Print the physical address  mapping  for  the  specified
         virtual  address,  if  possible. The ::vtop dcmd is only
         available when examining a kernel target, or  when  exa-
         mining  a user process inside a kernel crash dump (after
         a ::context dcmd has been issued).

         When examining a kernel target from the kernel  context,
         the -a option can be used to specify the address (as) of
         an alternate address space structure that should be used
         for the virtual to physical translation. By default, the
         kernel's address space is  used  for  translation.  This
         option  is available for active address spaces even when
         the dump content only contains kernel pages.


     [ address ] ::walk walker-name [ variable-name ]
         Walk through the elements of a data structure using  the
         specified  walker.  The  available walkers can be listed
         using the ::walkers dcmd. Some walkers operate on a glo-
         bal  data  structure  and  do  not  require  a  starting
         address. For example, walk the list of  proc  structures
         in  the kernel. Other walkers operate on a specific data
         structure whose address must  be  specified  explicitly.
         For  example,  given a pointer to an address space, walk
         the list  of  segments.  When  used  interactively,  the
         ::walk  dcmd  prints  the address of each element of the
         data structure in the default base. The dcmd can also be
         used  to provide a list of addresses for a pipeline. The
         walker name can use the backquote (`)  scoping  operator
         described  under dcmd and Walker Name Resolution, above.
         If the optional variable-name is specified,  the  speci-
         fied  variable  is  assigned  the value returned at each
         step of the walk when mdb invokes the next stage of  the
         pipeline.


     ::walkers
         List the available walkers and print a brief description
         for each one.


     ::save [ addr ] ::save [-p] [type] [member] variable
         Save values into an mdb variable such that the  variable
         can  be used in a pipeline. If only a variable is given,
         then the current value of dot is stored in the  variable
         and  dot is printed. If a type and member is on the com-
         mand line then the member is stored into  the  variable.
         Dot is always printed without its value being changed.


     ::whence [ -v ] name . . .
     ::which [ -v ] name ...
         Print the dmod that  exports  the  specified  dcmds  and
         walkers. These dcmds can be used to determine which dmod
         is currently providing  the  global  definition  of  the
         given  dcmd  or walker. Refer to the section on dcmd and
         Walker Name Resolution above  for  more  information  on
         global name resolution. The -v option causes the dcmd to
         print the alternate definitions of each dcmd and  walker
         in order of precedence.


     addr [ ,len ]::wp [ -/-dDestT ] [ -rwx ] [ -c cmd ]
     [ -n count ]
     addr [ ,len ] :a [ cmd . . . ]
     addr [ ,len ] :p [ cmd . . . ]
     addr [ ,len ] :w [ cmd . . . ]
         Set a watchpoint at the specified address. The length in
         bytes  of the watched region can be set by specifying an
         optional repeat count preceding the dcmd. If  no  length
         is  explicitly  set,  the  default is one byte. The ::wp
         dcmd allows the watchpoint to be configured  to  trigger
         on  any  combination  of  read  (-r  option),  write (-w
         option), or execute (-x option) access. The -d, -D,  -e,
         -s,  -t, -T, -c, and -n options have the same meaning as
         they do for the ::evset dcmd. The :a dcmd  sets  a  read
         access  watchpoint at the specified address. The :p dcmd
         sets an  execute  access  watchpoint  at  the  specified
         address.  The  :w dcmd sets a write access watchpoint at
         the specified address. The arguments following  the  :a,
         :p,  and  :w dcmds are concatenated together to form the
         callback  string.  If   this   string   contains   meta-
         characters, it must be quoted.


     ::xdata
         List the external data buffers exported by  the  current
         target.  External  data  buffers  represent  information
         associated with the target  that  can  not  be  accessed
         through  standard target facilities (that is, an address
         space, symbol table, or register set). These buffers can
         be consumed by dcmds; for more information, refer to the
         Oracle Solaris Modular Debugger Guide.


     :z
         Delete all event specifiers  from  the  list  of  traced
         software  events.  Event  specifiers can also be deleted
         using ::delete.

Options
     The following options are supported:

     -A
         Disables automatic loading of mdb modules.  By  default,
         mdb  attempts  to load debugger modules corresponding to
         the active shared libraries in a user  process  or  core
         file,  or  to  the  loaded  kernel  modules  in the live
         operating system or an operating system crash dump.


     -f
         Forces raw file debugging mode. By default, mdb attempts
         to infer whether the object and core file operands refer
         to a user executable and core  dump  or  to  a  pair  of
         operating system crash dump files. If the file type can-
         not be inferred, the debugger defaults to examining  the
         files  as plain binary data. The -f option forces mdb to
         interpret the arguments as a set of raw files  to  exam-
         ine.


     -F
         Forcibly takes  over  the  specified  user  process,  if
         necessary.  By  default, mdb refuses to attach to a user
         process that is already under  the  control  of  another
         debugging  tool,  such  as truss(1). With the -F option,
         mdb attaches to these processes anyway. This can produce
         unexpected  interactions between mdb and the other tools
         attempting to control the process.


     -I path
         Sets default path for locating macro files. Macro  files
         are  read  using  the  $<  or  $<<  dcmds. The path is a
         sequence of directory names delimited by colon (:) char-
         acters.  The  -I  include  path and -L library path (see
         below) can also contain any of the following tokens:

         %i
             Expands to the current instruction set  architecture
             (ISA) name ('sparc', `sparcv9', or `i386').


         %o
             Expands to the old value of the path being modified.
             This  is  useful  for appending or prepending direc-
             tories to an existing path.


         %p
             Expands to the current platform string (either uname
             -i or the platform string stored in the process core
             file or crash dump).

         %r
             Expands to the pathname of the  root  directory.  An
             alternate  root directory can be specified using the
             -R option. If no -R  option  is  present,  the  root
             directory  is  derived  dynamically from the path to
             the mdb executable itself. For example, if  /bin/mdb
             is   executed,   the   root   directory   is  /.  If
             /net/hostname/bin/mdb were executed, the root direc-
             tory would be derived as /net/hostname.


         %t
             Expands to the name of the current target.  This  is
             either  be the literal string `proc' (a user process
             or user process core file), `kvm'  (a  kernel  crash
             dump  or the live operating system), or `raw' (a raw
             file).

         The default include path for 32-bit mdb is:

           %r/usr/platform/%p/lib/adb:%r/usr/lib/adb


         The default include path for 64-bit mdb is:

           %r/usr/platform/%p/lib/adb/%i:%r/usr/lib/adb/%i




     -k
         Forces kernel debugging mode. By default,  mdb  attempts
         to infer whether the object and core file operands refer
         to a user executable and core dump,  or  to  a  pair  of
         operating  system crash dump files. The -k option forces
         mdb to assume these files  are  operating  system  crash
         dump  files.  If no object or core operand is specified,
         but the -k option  is  specified,  mdb  defaults  to  an
         object  file of /dev/ksyms and a core file of /dev/kmem.
         Read access to /dev/kmem is  restricted  to  group  sys.
         Write access requires ALL privileges.


     -K
         Load kmdb, stop the live running operating  system  ker-
         nel,  and  proceed  to  the  kmdb  debugger prompt. This
         option should only be used on the system console, as the
         subsequent kmdb prompt appears on the system console.

     -L path
         Sets default path for locating debugger modules. Modules
         are  loaded automatically on startup or using the ::load
         dcmd. The path is a sequence of directory  names  delim-
         ited  by  colon  (:) characters. The -L library path can
         also contain any of the tokens shown for -I above.


     -m
         Disables demand-loading of  kernel  module  symbols.  By
         default, mdb processes the list of loaded kernel modules
         and performs demand loading of per-module symbol tables.
         If  the  -m option is specified, mdb does not attempt to
         process the kernel module  list  or  provide  per-module
         symbol tables. As a result, mdb modules corresponding to
         active kernel modules are not loaded on startup.


     -M
         Preloads all kernel module symbols. By default, mdb per-
         forms demand-loading for kernel module symbols: the com-
         plete symbol table for a module is read when an  address
         is  that  module's  text  or data section is referenced.
         With the -M option, mdb loads the complete symbol  table
         of all kernel modules during startup.


     -o option
         Enables the specified debugger option. If the -o form of
         the  option  is  used, the specified option is disabled.
         Unless noted below, each option is off by  default.  mdb
         recognizes the following option arguments:

         adb
             Enables stricter adb(1) compatibility. The prompt is
             set  to the empty string and many mdb features, such
             as the output pager, is disabled.


         array_mem_limit=limit
             Sets the  default  limit  on  the  number  of  array
             members  that ::print displays. If limit is the spe-
             cial token none, all array members are displayed  by
             default.


         array_str_limit=limit
             Sets the default limit on the number  of  characters
             that  ::print attempts to display as an ASCII string
             when printing a char array. If limit is the  special
             token  none, the entire char array is displayed as a
             string by default.


         follow_exec_mode=mode
             Sets the debugger behavior for following an  exec(2)
             system call. The mode should be one of the following
             named constants:

             ask
                 If stdout is a  terminal  device,  the  debugger
                 stops after the exec(2) system call has returned
                 and then prompts the user to decide  whether  to
                 follow the exec or stop. If stdout is not a ter-
                 minal device, the ask mode defaults to stop.


             follow
                 The debugger follows the exec  by  automatically
                 continuing  the target process and resetting all
                 of its mappings and symbol tables based  on  the
                 new executable. The follow behavior is discussed
                 in more detail  under  NOTES,  Interaction  with
                 Exec, below.


             stop
                 The debugger stops  following  return  from  the
                 exec system call. The stop behavior is discussed
                 in more detail  under  NOTES,  Interaction  with
                 Exec, below.



         follow_fork_mode=mode
             Sets the debugger behavior for following a  fork(2),
             fork1(2),  or  vfork(2) system call. The mode should
             be one of the following named constants:

             ask
                 If stdout is a  terminal  device,  the  debugger
                 stops after the fork(2) system call has returned
                 and then prompts the user to decide  whether  to
                 follow  the  parent or child. If stdout is not a
                 terminal  device,  the  ask  mode  defaults   to
                 parent.

             parent
                 The debugger follows  the  parent  process,  and
                 detaches from the child process and sets it run-
                 ning.


             child
                 The debugger  follows  the  child  process,  and
                 detaches  from  the  parent  process and sets it
                 running.



         ignoreeof
             The debugger does not exit when an EOF sequence (^D)
             is  entered at the terminal. The ::quit dcmd must be
             used to quit.


         nostop
             Does not stop a user process when  attaching  to  it
             when the -p option is specified or when the ::attach
             or :A dcmds are  applied.  The  nostop  behavior  is
             described in more detail under NOTES, Process Attach
             and Release, below.


         nostrict
             The debugger will not enforce the usage restrictions
             of DCMDs.


         pager
             Enables the output pager (default).


         repeatlast
             If a NEWLINE is entered as the complete  command  at
             the  terminal, mdb repeats the previous command with
             the current value of dot. This option is implied  by
             -o adb.


         showlmid
             mdb provides support for symbol naming and identifi-
             cation  in  user  applications that make use of link
             maps  other  than  LM_ID_BASE  and  LM_ID_LDSO,   as
             described  in Symbol Name Resolution, above. Symbols
             on link maps other than LM_ID_BASE or LM_ID_LDSO  is
             shown  as  LMlmid`library`symbol,  where lmid is the
             link-map ID in the default output  radix  (16).  The
             user  can optionally configure mdb to show the link-
             map ID scope of all symbols and  objects,  including
             those  associated with LM_ID_BASE and LM_ID_LDSO, by
             enabling the showlmid option.  Built-in  dcmds  that
             deal  with  object  file names displays link-map IDs
             according to the value of showlmid above,  including
             ::nm, ::mappings, $m, and ::objects.



     -p pid
         Attaches to and stops the specified process-id. mdb uses
         the  /proc/pid/object/a.out  file as the executable file
         pathname.


     -P prompt
         Sets the command prompt. The default prompt is `> `.


     -R root
         Sets root directory for pathname expansion. By  default,
         the  root  directory is derived from the pathname of the
         mdb executable itself. The root directory is substituted
         in place of the %r token during pathname expansion.


     -s distance
         Sets  the  symbol  matching  distance  for   address-to-
         symbol-name  conversions  to  the specified distance. By
         default, mdb sets the distance to zero, which enables  a
         smart-matching   mode.   Each  ELF  symbol  table  entry
         includes a value V and size S, representing the size  of
         the function or data object in bytes. In smart mode, mdb
         matches an address A with the given symbol if  A  is  in
         the  range  [  V,  V  + S ). If any non-zero distance is
         specified, the same algorithm is  used,  but  S  in  the
         expression  above  is always the specified absolute dis-
         tance and the symbol size is ignored.


     -S
         Suppresses processing of the user's  ~/.mdbrc  file.  By
         default,  mdb  reads and processes the macro file .mdbrc
         if one is present  in  the  user's  home  directory,  as
         defined by $HOME. If the -S option is present, this file
         is not read.

     -u
         Forces user debugging mode. By default, mdb attempts  to
         infer whether the object and core file operands refer to
         a user executable and core dump, or to a pair of operat-
         ing system crash dump files. The -u option forces mdb to
         assume these files are not operating system  crash  dump
         files.


     -U
         Unload kmdb if it is loaded. You should unload kmdb when
         it  is not in use to release the memory used by the ker-
         nel debugger back to the free memory  available  to  the
         operating system.


     -V version
         Sets disassembler version. By default, mdb  attempts  to
         infer the appropriate disassembler version for the debug
         target. The disassembler can be set explicitly using the
         -V  option.  The  ::disasms  dcmd  lists  the  available
         disassembler versions.


     -w
         Opens the specified object and core files for writing.


     -W
         Permit access to memory addresses that are mapped to I/O
         devices.  By  default,  mdb  does  not allow such access
         because many devices do not provide hardware  protection
         against  invalid software manipulations. Use this option
         only when debugging device drivers and with caution.


     -y
         Sends explicit terminal initialization sequences for tty
         mode. Some terminals, such as cmdtool(1), require expli-
         cit initialization sequences to switch into a tty  mode.
         Without  this initialization sequence, terminal features
         such as standout mode can not be available to mdb.

Operands
     The following operands are supported:

     object
         Specifies an ELF format  object  file  to  examine.  mdb
         provides the ability to examine and edit ELF format exe-
         cutables (ET_EXEC), ELF dynamic library files  (ET_DYN),
         ELF  relocatable  object  files  (ET_REL), and operating
         system unix.X symbol table files.


     core
         Specifies an ELF process  core  file  (ET_CORE),  or  an
         operating  system  crash  dump  vmcore.X file. If an ELF
         core file operand is provided  without  a  corresponding
         object  file, mdb attempts to infer the name of the exe-
         cutable file that produced the core using  several  dif-
         ferent  algorithms. If no executable is found, mdb still
         executes, but some symbol information  can  be  unavail-
         able.

         If  system  crash  dump  file  is  provided  without   a
         corresponding  object  file,  mdb  attempts  to load the
         object file (the  unix  binary)  contained  in  vmcore.N
         file.


     suffix
         Specifies the numerical suffix representing a number  of
         operating  system  crash dump files. For example, if the
         suffix is `3', mdb infers that  it  should  examine  the
         files  `unix.3' and  all `vmcore-<section>.3' files . If
         these files do not exist,  but  `vmdump.3'  does  exist,
         then  a  message  is printed indicating that savecore -f
         vmdump.3 must be run first in order  to  uncompress  the
         dump  file.  If  vmcore.3 exists and some of the vmcore-
         <section>.3 files referenced by vmcore.3 do  not  exist,
         mdb  loads the files and issues warning that the virtual
         memory image will not be complete. The string of  digits
         are not interpreted as a suffix if an actual file of the
         same name is present in the current directory.

Usage
     mdb processes all input  files  (including  scripts,  object
     files, core files, and raw data files) in a large file aware
     fashion. See largefile(5) for  more  information  about  the
     processing  of  large files, which are files greater than or
     equal to 2 Gbytes (2^31 bytes).

Exit Status
     The following exit values are returned:

     0
         Debugger completed execution successfully.

     1
         A fatal error occurred.


     2
         Invalid command line options were specified.

Environment Variables
     HISTSIZE
         This variable is used to determine the maximum length of
         the  command  history  list.  If  this  variable  is not
         present, the default length is 128.


     HOME
         This variable is used to determine the pathname  of  the
         user's  home  directory, where a .mdbrc file can reside.
         If this variable is not present,  no  .mdbrc  processing
         occurs.


     SHELL
         This variable is used to determine the pathname  of  the
         shell  used to process shell escapes requested using the
         ! meta-character.  If  this  variable  is  not  present,
         /bin/sh is used.

Files
     $HOME/.mdbrc
         User  mdb  initialization  file.  The  .mdbrc  file,  if
         present,  is  processed  after the debug target has been
         initialized, but before module auto-loading is performed
         or any commands have been read from standard input.


     /dev/kmem
         Kernel virtual memory image device. This device  special
         file  is  used  as the core file when examining the live
         operating system.


     /dev/ksyms
         Kernel symbol table device. This device special file  is
         used  as the object file when examining the live operat-
         ing system.

     /proc/pid/*
         Process information files that are read  when  examining
         and controlling user processes.


     /usr/lib/adb
     /usr/platform/platform-name/lib/adb
         Default directories for macro files that are  read  with
         the  $<  and $<< dcmds. platform-name is the name of the
         platform, derived either from information in a core file
         or  crash  dump,  or  from  the current machine as if by
         uname -i (see uname(1)).


     /usr/lib/mdb
     /usr/platform/platform-name/lib/mdb
         Default directories for debugger modules that are loaded
         using  the ::load dcmd. platform-name is the name of the
         platform, derived either from information in a core file
         or  crash  dump,  or  from  the current machine as if by
         uname -i (see uname(1)).

Attributes
     See attributes(5) for descriptions of the  following  attri-
     butes:



     tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i)  ATTRI-
     BUTE TYPEATTRIBUTE VALUE _ Availabilitydeveloper/debug/mdb _
     Interface StabilityCommitted

See Also
     adb(1),  cmdtool(1),  gcore(1),  proc(1),  pgrep(1),  ps(1),
     stty(1),  truss(1), uname(1), coreadm(1M), dumpadm(1M), largefile(5),
     savecore(1M),  exec(2),  fork(2),  _lwp_self(2),
     pipe(2),  vfork(2),  dlopen(3C),  elf(3ELF),  libc_db(3LIB),
     libkvm(3LIB), libthread(3LIB), signal(3C),  signal.h(3HEAD),
     thr_self(3C), core(4), proc(4), attributes(5), largefile(5),
     threads(5), ksyms(7D), mem(7D)


     Oracle Solaris 11.3 Linkers and Libraries         Guide


     Oracle Solaris Modular Debugger Guide

Warnings
  Use of the Error Recovery Mechanism
     The debugger and its  dmods  execute  in  the  same  address
     space,  and  thus it is quite possible that a buggy dmod can
     cause mdb to dump  core  or  otherwise  misbehave.  The  mdb
     resume  capability,  described  above under Signal Handling,
     provides a limited recovery mechanism for these  situations.
     However,  it  is  not  possible for mdb to know definitively
     whether the dmod in question  has  corrupted  only  its  own
     state,  or  the  debugger's global state. Therefore a resume
     operation cannot be guaranteed to be safe, or to  prevent  a
     subsequent  crash  of  the  debugger.  The  safest course of
     action following a resume is to  save  any  important  debug
     information, and then quit and restart the debugger.

  Use of the Debugger to Modify the Live Operating System
     The use of the debugger to modify (that is,  write  to)  the
     address  space of live running operating system is extremely
     dangerous, and can result in a system panic in the event the
     user damages a kernel data structure.

Notes
  Limitations on Examining Process Core Files
     mdb does not provide  support  for  examining  process  core
     files  that were generated by a release of Solaris preceding
     Solaris 2.6.  When  debugging  core  files  generated  by  a
     release  of Solaris 9 or an earlier release, symbol informa-
     tion might not be available.  Since  the  text  section  and
     read-only  data is not present in those core files, the sym-
     bol information might not match the data present in the pro-
     cess  at  the  time  it  dumped core. In releases later than
     Solaris 9, text sections and read-only data are included  in
     core  files  by default. Users can configure their processes
     to  exclude  that  information   from   core   files   using
     coreadm(1M).  Thus,  the  information  presented  by mdb for
     those core files can not match the data that was present  at
     the  time  the  process dumped core. Core files from Solaris
     x86 systems can not be examined on  Solaris  SPARC  systems,
     and vice-versa.

  Limitations on Examining Crash Dump Files
     Crash dumps from Solaris 7 and earlier releases can only  be
     examined  with  the aid of the libkvm from the corresponding
     operating system release. If a crash dump from one operating
     system  release is examined using the dmods from a different
     operating system release, changes in the kernel  implementa-
     tion  can  prevent  some dcmds or walkers from working prop-
     erly. mdb issues a warning message if it detects this condi-
     tion.  Crash dumps from Solaris x86 systems can not be exam-
     ined on Solaris SPARC systems, and vice-versa.

  Relationship Between 32-bit and 64-bit Debugger
     mdb provides support for debugging both  32-bit  and  64-bit
     programs. Once it has examined the target and determined its
     data model, mdb automatically  re-executes  the  mdb  binary
     that  has  the  same data model as the target, if necessary.
     This  approach  simplifies  the  task  of  writing  debugger
     modules,  because  the  modules that are loaded use the same
     data model as the primary target. Only the  64-bit  debugger
     can  be  used  to  debug  64-bit target programs. The 64-bit
     debugger can only be used on a system that  is  running  the
     64-bit operating environment.


     The debugger can also need to re-execute itself when  debug-
     ging  a 32-bit process that execs a 64-bit process, or vice-
     versa. The handling of this situation is discussed  in  more
     detail under Interaction with Exec, below.

  Interaction with Exec
     When a controlled process performs a successful exec(2), the
     behavior  of  the  debugger  is  controlled  by the ::set -o
     follow_exec_mode option, as described above. If the debugger
     and victim process have the same data model, then the "stop"
     and "follow" modes determine whether mdb automatically  con-
     tinues  the target or returns to the debugger prompt follow-
     ing the exec. If the debugger and victim process have a dif-
     ferent  data model, then the "follow" behavior causes mdb to
     automatically re-exec the mdb binary  with  the  appropriate
     data model and to re-attach to the process, still stopped on
     return from the exec. Not all debugger  state  is  preserved
     across this re-exec.


     If a 32-bit victim process  execs  a  64-bit  program,  then
     "stop" returns to the command prompt, but the debugger is no
     longer able to examine the process because it is  now  using
     the  64-bit  data  model.  To  resume debugging, execute the
     ::release -a dcmd, quit mdb, and then execute mdb -p pid  to
     re-attach the 64-bit debugger to the process.


     If a 64-bit victim process  execs  a  32-bit  program,  then
     "stop"  returns to the command prompt, but the debugger only
     provides limited capabilities for examining the new process.
     All built-in dcmds work as advertised, but loadable dcmds do
     not since they do  not  perform  data  model  conversion  of
     structures.  The  user  should  release  and  re-attach  the
     debugger to the process  as  described  above  in  order  to
     restore full debugging capabilities.

  Interaction with Job Control

     If the debugger is attached to a process that is stopped  by
     job  control  (that  is,  it stopped in response to SIGTSTP,
     SIGTTIN, or SIGTTOU), the process can not be able to be  set
     running  again  when  it is continued by a continue dcmd. If
     the victim process is a member of the same session (that is,
     it  shares  the  same  controlling  terminal  as  mdb),  mdb
     attempts to bring the associated process group to the  fore-
     ground and to continue the process with SIGCONT to resume it
     from job control stop. When mdb is detached from such a pro-
     cess, it restores the process group to the background before
     exiting. If the victim process is not a member of  the  same
     session,  mdb  cannot  safely bring the process group to the
     foreground, so it continues the process with respect to  the
     debugger,  but  the  process remains stopped by job control.
     mdb prints a warning in this case, and the user  must  issue
     an  "fg"  command  from  the  appropriate  shell in order to
     resume the process.

  Process Attach and Release
     When mdb attaches to  a  running  process,  the  process  is
     stopped  and remains stopped until one of the continue dcmds
     is applied, or the debugger quits. If the -o  nostop  option
     is enabled prior to attaching the debugger to a process with
     -p, or prior to issuing  an  ::attach  or  :A  command,  mdb
     attaches to the process but does not stop it. While the pro-
     cess is still running, it can be inspected as usual  (albeit
     with  inconsistent results) and breakpoints or other tracing
     flags might be enabled. If the :c or ::cont dcmds  are  exe-
     cuted  while  the process is running, the debugger waits for
     the process to stop. If no traced software events occur, the
     user  can send an interrupt (^C) after :c or ::cont to force
     the process to stop and return control to the debugger.


     mdb releases the current running process (if any)  when  the
     :R,  ::release, :r, ::run, $q, or ::quit dcmds are executed,
     or when the debugger terminates as the result of an  EOF  or
     signal.  If  the  process  was  originally  created  by  the
     debugger using :r or ::run, it is forcibly terminated as  if
     by  SIGKILL  when it is released. If the process was already
     running prior to attaching mdb to  it,  it  is  set  running
     again  when  it  is  released. A process can be released and
     left stopped and abandoned using the ::release -a option.

  Symbolic Debugging Information
     The ::list, ::offsetof, ::print, and ::sizeof dcmds  require
     that  one  or  more load objects contain compressed symbolic
     debugging information suitable for use with mdb. This infor-
     mation  is currently only available for certain Solaris ker-
     nel modules.

  Developer Information
     The Oracle Solaris Modular Debugger Guide  provides  a  more
     detailed description of mdb features, as well as information
     for debugger module developers.


     The header file <sys/mdb_modapi.h> contains  prototypes  for
     the   functions   in   the   MDB   Module   API,   and   the
     /source/demo/mdb-examples package provides source  code  for
     an example module in the directory /usr/demo/mdb.
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