documentation/debugger.sgml

   1   <chapter id="debugger">
   2     <title>Debugging Wine</title>
   3
   4     <sect1 id="dbg-intro">
   5       <title>Introduction</title>
   6
   7       <sect2>
   8         <title>Processes and threads: in underlying OS and in Windows</title>
   9
  10         <para>
  11           Before going into the depths of debugging in Wine, here's
  12           a small overview of process and thread handling in Wine.
  13           It has to be clear that there are two different beasts:
  14           processes/threads from the Unix point of view and
  15           processes/threads from a Windows point of view.
  16         </para>
  17         <para>
  18           Each Windows' thread is implemented as a Unix process (under
  19           Linux using the <function>clone</function> syscall), meaning
  20           that all threads of a same Windows' process share the same
  21           (unix) address space.
  22         </para>
  23         <para>
  24           In the following:
  25         </para>
  26         <itemizedlist>
  27           <listitem>
  28             <para>
  29               <varname>W-process</varname> means a process in Windows' terminology
  30             </para>
  31           </listitem>
  32           <listitem>
  33             <para>
  34               <varname>U-process</varname> means a process in Unix' terminology
  35             </para>
  36           </listitem>
  37           <listitem>
  38             <para>
  39               <varname>W-thread</varname> means a thread in Windows' terminology
  40             </para>
  41           </listitem>
  42         </itemizedlist>
  43         <para>
  44           A <varname>W-process</varname> is made of one or several
  45           <varname>W-threads</varname>. Each
  46           <varname>W-thread</varname> is mapped to one and only one
  47           <varname>U-process</varname>. All
  48           <varname>U-processes</varname> of a same
  49           <varname>W-process</varname> share the same address space.
  50         </para>
  51         <para>
  52           Each Unix process can be identified by two values:
  53         </para>
  54         <itemizedlist>
  55           <listitem>
  56             <para>
  57               the Unix process id (<varname>upid</varname> in the following)
  58             </para>
  59           </listitem>
  60           <listitem>
  61             <para>
  62               the Windows's thread id (<varname>tid</varname>)
  63             </para>
  64           </listitem>
  65         </itemizedlist>
  66         <para>
  67           Each Windows' process has also a Windows' process id
  68           (<varname>wpid</varname> in the following). It must be clear
  69           that <varname>upid</varname> and <varname>wpid</varname> are
  70           different and shall not be used instead of the other.
  71         </para>
  72         <para>
  73           <varname>Wpid</varname> and <varname>tid</varname> are
  74           defined (Windows) system wide. They must not be confused
  75           with process or thread handles which, as any handle, is an
  76           indirection to a system object (in this case process or
  77           thread). A same process can have several different handles
  78           on the same kernel object. The handles can be defined as
  79           local (the values is only valid in a process), or system
  80           wide (the same handle can be used by any
  81           <varname>W-process</varname>).
  82         </para>
  83       </sect2>
  84
  85       <sect2>
  86         <title>Wine, debugging and WineDbg</title>
  87
  88         <para>
  89           When talking of debugging in Wine, there are at least two
  90           levels to think of:
  91         </para>
  92         <itemizedlist>
  93           <listitem>
  94             <para>
  95               the Windows' debugging API.
  96             </para>
  97           </listitem>
  98           <listitem>
  99             <para>
 100               the Wine integrated debugger, dubbed <command>WineDbg</command>.
 101             </para>
 102           </listitem>
 103         </itemizedlist>
 104         <para>
 105           Wine implements most of the Windows' debugging API (the
 106           part in <filename>KERNEL32.DLL</filename>, not the one in
 107           <filename>IMAGEHLP.DLL</filename>), and allows any program
 108           (emulated or Winelib) using that API to debug a
 109           <varname>W-process</varname>.
 110         </para>
 111         <para>
 112           <command>WineDbg</command> is a Winelib application making
 113           use of this API to allow debugging both any Wine or Winelib
 114           applications as well as Wine itself (kernel and all DLLs).
 115         </para>
 116       </sect2>
 117     </sect1>
 118
 119
 120     <sect1 id="dbg-modes">
 121       <title>WineDbg's modes of invocation</title>
 122
 123       <sect2>
 124         <title>Starting a process</title>
 125
 126         <para>
 127           Any application (either a Windows' native executable, or a
 128           Winelib application) can be run through
 129           <command>WineDbg</command>. Command line options and tricks
 130           are the same as for wine:
 131         </para>
 132         <screen>
 133 winedbg telnet.exe
 134 winedbg "hl.exe -windowed"
 135         </screen>
 136       </sect2>
 137
 138       <sect2>
 139         <title>Attaching</title>
 140
 141         <para>
 142           <command>WineDbg</command> can also be launched without any
 143           command line argument: <command>WineDbg</command> is started
 144           without any attached process. You can get a list of running
 145           <varname>W-processes</varname> (and their
 146           <varname>wpid</varname>'s) using the <command>walk
 147             process</command> command, and then, with the
 148           <command>attach</command> command, pick up the
 149           <varname>wpid</varname> of the <varname>W-process</varname>
 150           you want to debug. This is a neat feature as it allows you
 151           to debug an already started application.
 152          </para>
 153       </sect2>
 154
 155       <sect2 id="dbg-on-exception">
 156         <title id="dbg-exception-title">On exceptions</title>
 157
 158         <para>
 159           When something goes wrong, Windows tracks this as an
 160           exception. Exceptions exist for segmentation violation,
 161           stack overflow, division by zero, etc.
 162         </para>
 163         <para>
 164           When an exception occurs, Wine checks if the <varname>W-process</varname> is
 165           debugged. If so, the exception event is sent to the
 166           debugger, which takes care of it: end of the story. This
 167           mechanism is part of the standard Windows' debugging API.
 168         </para>
 169         <para>
 170           If the <varname>W-process</varname> is not debugged, Wine
 171           tries to launch a debugger. This debugger (normally
 172           <command>WineDbg</command>, see III Configuration for more
 173           details), at startup, attaches to the
 174           <varname>W-process</varname> which generated the exception
 175           event. In this case, you are able to look at the causes of
 176           the exception, and either fix the causes (and continue
 177           further the execution) or dig deeper to understand what went
 178           wrong.
 179         </para>
 180         <para>
 181           If <command>WineDbg</command> is the standard debugger, the
 182           <command>pass</command> and <command>cont</command> commands
 183           are the two ways to let the process go further for the
 184           handling of the  exception event.
 185         </para>
 186         <para>
 187           To be more precise on the way Wine (and Windows) generates
 188           exception events, when a fault occurs (segmentation
 189           violation, stack overflow...), the event is first sent to
 190           the debugger (this is known as a first chance exception).
 191           The debugger can give two answers:
 192         </para>
 193
 194         <variablelist>
 195           <varlistentry>
 196             <term>continue:</term>
 197             <listitem>
 198               <para>
 199                 the debugger had the ability to correct what's
 200                 generated the exception, and is now able to continue
 201                 process execution.
 202               </para>
 203             </listitem>
 204           </varlistentry>
 205           <varlistentry>
 206             <term>pass:</term>
 207             <listitem>
 208               <para>
 209                 the debugger couldn't correct the cause of the
 210                 first chance exception. Wine will now try to walk
 211                 the list of exception handlers to see if one of them
 212                 can handle the exception. If no exception handler is
 213                 found, the exception is sent once again to the
 214                 debugger to indicate the failure of the exception
 215                 handling.
 216               </para>
 217             </listitem>
 218           </varlistentry>
 219         </variablelist>
 220         <note>
 221           <para>
 222             since some of Wine's code uses exceptions and
 223             <function>try/catch</function> blocks to provide some
 224             functionality, <command>WineDbg</command> can be entered
 225             in such cases with segv exceptions. This happens, for
 226             example, with <function>IsBadReadPtr</function> function.
 227             In that case, the <command>pass</command> command shall be
 228             used, to let the handling of the exception to be done by
 229             the <function>catch</function> block in
 230             <function>IsBadReadPtr</function>.
 231           </para>
 232         </note>
 233       </sect2>
 234
 235       <sect2 id="interrupt">
 236         <title>Interrupting</title>
 237
 238         <para>
 239           You can stop the debugger while it's running by hitting
 240           Ctrl-C in its window. This will stop the debugged process,
 241           and let you manipulate the current context.
 242         </para>
 243       </sect2>
 244
 245       <sect2>
 246         <title>Quitting</title>
 247
 248         <para>
 249           Wine supports the new XP APIs, allowing for a debugger to
 250           detach from a program being debugged (see
 251           <command>detach</command> command). Unfortunately, as the
 252           debugger cannot, for now, neither clear its internal
 253           information, nor restart a new process, the debugger, after
 254           detaching itself, cannot do much except being quitted.
 255         </para>
 256       </sect2>
 257     </sect1>
 258
 259
 260     <sect1 id="wine-debugger">
 261       <title>Using the Wine Debugger</title>
 262
 263       <para>
 264         This section describes where to start debugging Wine. If at any
 265         point you get stuck and want to ask for help, please read the
 266         <emphasis>How to Report A Bug</emphasis> section of the
 267         <emphasis>Wine Users Guide</emphasis> for information on how to write
 268         useful bug reports.
 269       </para>
 270
 271       <sect2>
 272         <title>Crashes</title>
 273
 274         <para>
 275           These usually show up like this:
 276         </para>
 277         <screen>
 278 |Unexpected Windows program segfault - opcode = 8b
 279 |Segmentation fault in Windows program 1b7:c41.
 280 |Loading symbols from ELF file /root/wine/wine...
 281 |....more Loading symbols from ...
 282 |In 16 bit mode.
 283 |Register dump:
 284 | CS:01b7 SS:016f DS:0287 ES:0000
 285 | IP:0c41 SP:878a BP:8796 FLAGS:0246
 286 | AX:811e BX:0000 CX:0000 DX:0000 SI:0001 DI:ffff
 287 |Stack dump:
 288 |0x016f:0x878a:  0001 016f ffed 0000 0000 0287 890b 1e5b
 289 |0x016f:0x879a:  01b7 0001 000d 1050 08b7 016f 0001 000d
 290 |0x016f:0x87aa:  000a 0003 0004 0000 0007 0007 0190 0000
 291 |0x016f:0x87ba:
 292 |
 293 |0050: sel=0287 base=40211d30 limit=0b93f (bytes) 16-bit rw-
 294 |Backtrace:
 295 |0 0x01b7:0x0c41 (PXSRV_FONGETFACENAME+0x7c)
 296 |1 0x01b7:0x1e5b (PXSRV_FONPUTCATFONT+0x2cd)
 297 |2 0x01a7:0x05aa
 298 |3 0x01b7:0x0768 (PXSRV_FONINITFONTS+0x81)
 299 |4 0x014f:0x03ed (PDOXWIN_@SQLCURCB$Q6CBTYPEULN8CBSCTYPE+0x1b1)
 300 |5 0x013f:0x00ac
 301 |
 302 |0x01b7:0x0c41 (PXSRV_FONGETFACENAME+0x7c):  movw        %es:0x38(%bx),%dx
 303         </screen>
 304         <para>
 305           Steps to debug a crash. You may stop at any step, but please
 306           report the bug and provide as much of the information
 307           gathered to the bug report as feasible.
 308         </para>
 309
 310         <orderedlist>
 311           <listitem>
 312             <para>
 313               Get the reason for the crash. This is usually an access to
 314               an invalid selector, an access to an out of range address
 315               in a valid selector, popping a segment register from the
 316               stack or the like. When reporting a crash, report this
 317               <emphasis>whole</emphasis> crashdump even if it doesn't
 318               make sense to you.
 319             </para>
 320             <para>
 321               (In this case it is access to an invalid selector, for
 322               <systemitem>%es</systemitem> is <literal>0000</literal>, as
 323               seen in the register dump).
 324             </para>
 325           </listitem>
 326           <listitem>
 327             <para>
 328               Determine the cause of the crash. Since this is usually
 329               a primary/secondary reaction to a failed or misbehaving
 330               Wine function, rerun Wine with the<parameter>WINEDEBUG=+relay</parameter>
 331               environment variable set. This will
 332               generate quite a lot of output, but usually the reason is
 333               located in the last call(s).  Those lines usually look like
 334               this:
 335             </para>
 336             <screen>
 337 |Call KERNEL.90: LSTRLEN(0227:0692 "text") ret=01e7:2ce7 ds=0227
 338       ^^^^^^^^^  ^       ^^^^^^^^^ ^^^^^^      ^^^^^^^^^    ^^^^
 339       |          |       |         |           |            |Datasegment
 340       |          |       |         |           |Return address
 341       |          |       |         |textual parameter
 342       |          |       |
 343       |          |       |Argument(s). This one is a win16 segmented pointer.
 344       |          |Function called.
 345       |The module, the function is called in. In this case it is KERNEL.
 346
 347 |Ret  KERNEL.90: LSTRLEN() retval=0x0004 ret=01e7:2ce7 ds=0227
 348                                   ^^^^^^
 349                                   |Returnvalue is 16 bit and has the value 4.
 350             </screen>
 351           </listitem>
 352           <listitem>
 353             <para>
 354               If you have found a misbehaving function, try to find out
 355               why it misbehaves. Find the function in the source code.
 356               Try to make sense of the arguments passed. Usually there is
 357               a <function>WINE_DEFAULT_DEBUG_CHANNEL(&lt;channel>);</function>
 358               at the beginning of the file. Rerun wine with the
 359               <parameter>WINEDEBUG=+xyz,+relay</parameter> environment variable set.
 360             </para>
 361             <para>
 362               Occasionally there are additional debug channels defined at the
 363               beginning of the file in the form.
 364               <function>WINE_DECLARE_DEBUG_CHANNEL(&lt;channel>);</function>
 365               If so the offending function may also uses one of these alternate
 366               channels. Look through the the function for
 367              <function>TRACE_(&lt;channel>)(" ... /n");</function> and add any
 368              additional channels to the commandline.
 369             </para>
 370           </listitem>
 371           <listitem>
 372             <para>
 373               Additional information on how to debug using the internal
 374               debugger can be  found in
 375               <filename>programs/winedbg/README</filename>.
 376             </para>
 377           </listitem>
 378           <listitem>
 379             <para>
 380               If this information isn't clear enough or if you want to
 381               know more about what's happening in the function itself,
 382               try running wine with <parameter>WINEDEBUG=+all</parameter>,
 383               which dumps ALL included debug
 384               information in wine.
 385             </para>
 386           </listitem>
 387           <listitem>
 388             <para>
 389               If even that isn't enough, add more debug output for yourself
 390               into the functions you find relevant. See The section on Debug
 391               Logging in this guide for more information. You might
 392               also try to run the program in <command>gdb</command>
 393               instead of using the Wine debugger. If you do that, use
 394               <parameter>handle SIGSEGV nostop noprint</parameter> to
 395               disable the handling of seg faults inside
 396               <command>gdb</command> (needed for Win16).
 397             </para>
 398           </listitem>
 399           <listitem>
 400             <para>
 401               You can also set a breakpoint for that function. Start wine
 402               useing <command>winedbg</command> instead of
 403               <command>wine</command>. Once the debugger is is running enter
 404               <command>break</command> <parameter>KERNEL_LSTRLEN</parameter>
 405               (replace by function you want to debug, CASE IS RELEVANT)
 406               to set a breakpoint.  Then
 407               use <command>continue</command> to start normal
 408               program-execution. Wine will stop if it reaches the
 409               breakpoint. If the program isn't yet at the crashing call
 410               of that function, use <command>continue</command> again
 411               until you are about to enter that function. You may now
 412               proceed with single-stepping the function until you reach
 413               the point of crash. Use the other debugger commands to
 414               print registers and the like.
 415             </para>
 416           </listitem>
 417         </orderedlist>
 418       </sect2>
 419
 420       <sect2>
 421         <title>Program hangs, nothing happens</title>
 422
 423         <para>
 424           Start the program with <command>winedbg</command> instead of
 425           <command>wine</command>. When the program locks up switch to the
 426           winedbg terminal and press
 427           <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo>. this
 428           will stop the program and let you debug the program as you would for
 429           a crash.
 430         </para>
 431       </sect2>
 432
 433       <sect2>
 434         <title>Program reports an error with a Messagebox</title>
 435
 436         <para>
 437           Sometimes programs are reporting failure using more or
 438           less nondescript messageboxes. We can debug this using the
 439           same method as Crashes, but there is one problem... For
 440           setting up a message box the program also calls Wine
 441           producing huge chunks of debug code.
 442         </para>
 443         <para>
 444           Since the failure happens usually directly before setting up
 445           the Messagebox you can start winedbg and set a
 446           breakpoint at <function>MessageBoxA</function> (called by win16
 447           and win32 programs) and proceed with
 448           <command>continue</command>. With <parameter>WINEDEBUG=+all</parameter>
 449           Wine will now stop directly before setting
 450           up the Messagebox. Proceed as explained above.
 451         </para>
 452         <para>
 453           You can also run wine using <command>WINEDEBUG=+relay wine
 454             program.exe 2>&1 | less -i</command> and in
 455           <command>less</command> search for <quote>MessageBox</quote>.
 456         </para>
 457       </sect2>
 458
 459       <sect2>
 460         <title>Disassembling programs:</title>
 461
 462         <para>
 463           You may also try to disassemble the offending program to
 464           check for undocumented features and/or use of them.
 465         </para>
 466         <para>
 467           The best, freely available, disassembler for Win16 programs is
 468           <application>Windows Codeback</application>, archive name
 469           <filename>wcbxxx.zip</> (e.g. <filename>wcb105a.zip</>), which
 470           usually can be found in the <filename>Cica-Mirror</filename>
 471           subdirectory on the Wine ftp sites. (See <filename>ANNOUNCE</>).
 472         </para>
 473         <para>
 474           Disassembling win32 programs is possible using
 475           <application>Windows Disassembler 32</>. Look for
 476           a file called <filename>w32dsm87.zip</> (or similar)
 477           on <ulink url="http://www.winsite.com/">http://www.winsite.com</>
 478           and mirrors.  The shareware version does not allow saving of
 479           disassembly listings. You can also use the newer (and in the
 480           full version better) <application>Interactive
 481             Disassembler</application> (IDA) from the ftp sites mentioned
 482           at the end of the document. Understanding disassembled code is
 483           mostly a question of exercise.
 484         </para>
 485         <para>
 486           Most code out there uses standard C function entries (for it
 487           is usually  written in C). Win16 function entries usually
 488           look like that:
 489         </para>
 490         <programlisting>
 491 push bp
 492 mov bp, sp
 493 ... function code ..
 494 retf XXXX       &lt;--------- XXXX is number of bytes of arguments
 495         </programlisting>
 496         <para>
 497           This is a <function>FAR</function> function with no local
 498           storage. The arguments usually start at
 499           <literal>[bp+6]</literal> with increasing offsets. Note, that
 500           <literal>[bp+6]</literal> belongs to the
 501           <emphasis>rightmost</emphasis> argument, for exported win16
 502           functions use the PASCAL calling convention. So, if we use
 503           <function>strcmp(a,b)</function> with <parameter>a</parameter>
 504           and <parameter>b</parameter> both 32 bit variables
 505           <parameter>b</parameter> would be at <literal>[bp+6]</literal>
 506           and <parameter>a</parameter> at <literal>[bp+10]</literal>.
 507         </para>
 508         <para>
 509           Most functions make also use of local storage in the stackframe:
 510         </para>
 511         <programlisting>
 512 enter 0086, 00
 513 ... function code ...
 514 leave
 515 retf XXXX
 516         </programlisting>
 517         <para>
 518           This does mostly the same as above, but also adds
 519           <literal>0x86</literal> bytes of stackstorage, which is
 520           accessed using <literal>[bp-xx]</literal>. Before calling a
 521           function, arguments are pushed on the stack using something
 522           like this:
 523         </para>
 524         <programlisting>
 525 push word ptr [bp-02]   &lt;- will be at [bp+8]
 526 push di                 &lt;- will be at [bp+6]
 527 call KERNEL.LSTRLEN
 528         </programlisting>
 529         <para>
 530           Here first the selector and then the offset to the passed
 531           string are pushed.
 532         </para>
 533       </sect2>
 534
 535       <sect2>
 536         <title>Sample debugging session:</title>
 537
 538         <para>
 539           Let's debug the infamous Word <filename>SHARE.EXE</filename>
 540           messagebox:
 541         </para>
 542         <screen>
 543 |marcus@jet $ wine winword.exe
 544 |            +---------------------------------------------+
 545 |            | !  You must leave Windows and load SHARE.EXE|
 546 |            |    before starting Word.                    |
 547 |            +---------------------------------------------+
 548         </screen>
 549         <screen>
 550 |marcus@jet $ WINEDEBUG=+relay,-debug wine winword.exe
 551 |CallTo32(wndproc=0x40065bc0,hwnd=000001ac,msg=00000081,wp=00000000,lp=00000000)
 552 |Win16 task 'winword': Breakpoint 1 at 0x01d7:0x001a
 553 |CallTo16(func=0127:0070,ds=0927)
 554 |Call WPROCS.24: TASK_RESCHEDULE() ret=00b7:1456 ds=0927
 555 |Ret  WPROCS.24: TASK_RESCHEDULE() retval=0x8672 ret=00b7:1456 ds=0927
 556 |CallTo16(func=01d7:001a,ds=0927)
 557 |     AX=0000 BX=3cb4 CX=1f40 DX=0000 SI=0000 DI=0927 BP=0000 ES=11f7
 558 |Loading symbols: /home/marcus/wine/wine...
 559 |Stopped on breakpoint 1 at 0x01d7:0x001a
 560 |In 16 bit mode.
 561 |Wine-dbg>break MessageBoxA                          &lt;---- Set Breakpoint
 562 |Breakpoint 2 at 0x40189100 (MessageBoxA [msgbox.c:190])
 563 |Wine-dbg>c                                            &lt;---- Continue
 564 |Call KERNEL.91: INITTASK() ret=0157:0022 ds=08a7
 565 |     AX=0000 BX=3cb4 CX=1f40 DX=0000 SI=0000 DI=08a7 ES=11d7 EFL=00000286
 566 |CallTo16(func=090f:085c,ds=0dcf,0x0000,0x0000,0x0000,0x0000,0x0800,0x0000,0x0000,0x0dcf)
 567 |...                                                   &lt;----- Much debugoutput
 568 |Call KERNEL.136: GETDRIVETYPE(0x0000) ret=060f:097b ds=0927
 569                                ^^^^^^ Drive 0 (A:)
 570 |Ret  KERNEL.136: GETDRIVETYPE() retval=0x0002 ret=060f:097b ds=0927
 571                                         ^^^^^^  DRIVE_REMOVEABLE
 572                                                 (It is a floppy diskdrive.)
 573
 574 |Call KERNEL.136: GETDRIVETYPE(0x0001) ret=060f:097b ds=0927
 575                                ^^^^^^ Drive 1 (B:)
 576 |Ret  KERNEL.136: GETDRIVETYPE() retval=0x0000 ret=060f:097b ds=0927
 577                                         ^^^^^^  DRIVE_CANNOTDETERMINE
 578                                                 (I don't have drive B: assigned)
 579
 580 |Call KERNEL.136: GETDRIVETYPE(0x0002) ret=060f:097b ds=0927
 581                                ^^^^^^^ Drive 2 (C:)
 582 |Ret  KERNEL.136: GETDRIVETYPE() retval=0x0003 ret=060f:097b ds=0927
 583                                         ^^^^^^ DRIVE_FIXED
 584                                                (specified as a harddisk)
 585
 586 |Call KERNEL.97: GETTEMPFILENAME(0x00c3,0x09278364"doc",0x0000,0927:8248) ret=060f:09b1 ds=0927
 587                                  ^^^^^^           ^^^^^        ^^^^^^^^^
 588                                  |                |            |buffer for fname
 589                                  |                |temporary name ~docXXXX.tmp
 590                                  |Force use of Drive C:.
 591
 592 |Warning: GetTempFileName returns 'C:~doc9281.tmp', which doesn't seem to be writeable.
 593 |Please check your configuration file if this generates a failure.
 594         </screen>
 595         <para>
 596           Whoops, it even detects that something is wrong!
 597         </para>
 598         <screen>
 599 |Ret  KERNEL.97: GETTEMPFILENAME() retval=0x9281 ret=060f:09b1 ds=0927
 600                                           ^^^^^^ Temporary storage ID
 601
 602 |Call KERNEL.74: OPENFILE(0x09278248"C:~doc9281.tmp",0927:82da,0x1012) ret=060f:09d8 ds=0927
 603                                     ^^^^^^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^
 604                                     |filename        |OFSTRUCT |open mode:
 605
 606                                        OF_CREATE|OF_SHARE_EXCLUSIVE|OF_READWRITE
 607         </screen>
 608         <para>
 609           This fails, since my <medialabel>C:</medialabel> drive is in
 610           this case mounted readonly.
 611         </para>
 612         <screen>
 613 |Ret  KERNEL.74: OPENFILE() retval=0xffff ret=060f:09d8 ds=0927
 614                                    ^^^^^^ HFILE_ERROR16, yes, it failed.
 615
 616 |Call USER.1: MESSAGEBOX(0x0000,0x09278376"You must close Windows and load SHARE.EXE before you start Word.",0x00000000,0x1030) ret=060f:084f ds=0927
 617         </screen>
 618         <para>
 619           And MessageBox'ed.
 620         </para>
 621         <screen>
 622 |Stopped on breakpoint 2 at 0x40189100 (MessageBoxA [msgbox.c:190])
 623 |190     {              &lt;- the sourceline
 624 In 32 bit mode.
 625 Wine-dbg>
 626         </screen>
 627         <para>
 628           The code seems to find a writeable harddisk and tries to create
 629           a file there. To work around this bug, you can define
 630           <medialabel>C:</medialabel> as a networkdrive, which is ignored
 631           by the code above.
 632         </para>
 633       </sect2>
 634
 635       <sect2>
 636         <title>Debugging Tips</title>
 637
 638         <para>
 639           Here are some additional debugging tips:
 640         </para>
 641
 642         <itemizedlist>
 643           <listitem>
 644             <para>
 645               If you have a program crashing at such an early loader phase that you can't
 646               use the Wine debugger normally, but Wine already executes the program's
 647               start code, then you may use a special trick. You should do a
 648               <programlisting>
 649 WINEDEBUG=+relay wine program
 650               </programlisting>
 651               to get a listing of the functions the program calls in its start function.
 652               Now you do a
 653               <programlisting>
 654 winedbg winfile.exe
 655               </programlisting>
 656             </para>
 657             <para>
 658               This way, you get into <command>winedbg</command>. Now you
 659               can set a breakpoint on any function the program calls in
 660               the start function and just type <userinput>c</userinput>
 661               to bypass the eventual calls of Winfile to this function
 662               until you are finally at the place where this function gets
 663               called by the crashing start function. Now you can proceed
 664               with your debugging as usual.
 665             </para>
 666           </listitem>
 667           <listitem>
 668             <para>
 669               If you try to run a program and it quits after showing an error messagebox,
 670               the problem can usually be identified in the return value of one of the
 671               functions executed before <function>MessageBox()</function>.
 672               That's why you should re-run the program with e.g.
 673               <programlisting>
 674 WINEDEBUG=+relay wine  &lt;program name> &>relmsg
 675               </programlisting>
 676               Then do a <command>more relmsg</command> and search for the
 677               last occurrence of a call to the string "MESSAGEBOX". This is a line like
 678               <programlisting>
 679 Call USER.1: MESSAGEBOX(0x0000,0x01ff1246 "Runtime error 219 at 0004:1056.",0x00000000,0x1010) ret=01f7:2160 ds=01ff
 680               </programlisting>
 681               In my example the lines before the call to
 682               <function>MessageBox()</function> look like that:
 683               <programlisting>
 684 Call KERNEL.96: FREELIBRARY(0x0347) ret=01cf:1033 ds=01ff
 685 CallTo16(func=033f:0072,ds=01ff,0x0000)
 686 Ret  KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:1033 ds=01ff
 687 Call KERNEL.96: FREELIBRARY(0x036f) ret=01cf:1043 ds=01ff
 688 CallTo16(func=0367:0072,ds=01ff,0x0000)
 689 Ret  KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:1043 ds=01ff
 690 Call KERNEL.96: FREELIBRARY(0x031f) ret=01cf:105c ds=01ff
 691 CallTo16(func=0317:0072,ds=01ff,0x0000)
 692 Ret  KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:105c ds=01ff
 693 Call USER.171: WINHELP(0x02ac,0x01ff05b4 "COMET.HLP",0x0002,0x00000000) ret=01cf:1070 ds=01ff
 694 CallTo16(func=0117:0080,ds=01ff)
 695 Call WPROCS.24: TASK_RESCHEDULE() ret=00a7:0a2d ds=002b
 696 Ret  WPROCS.24: TASK_RESCHEDULE() retval=0x0000 ret=00a7:0a2d ds=002b
 697 Ret  USER.171: WINHELP() retval=0x0001 ret=01cf:1070 ds=01ff
 698 Call KERNEL.96: FREELIBRARY(0x01be) ret=01df:3e29 ds=01ff
 699 Ret  KERNEL.96: FREELIBRARY() retval=0x0000 ret=01df:3e29 ds=01ff
 700 Call KERNEL.52: FREEPROCINSTANCE(0x02cf00ba) ret=01f7:1460 ds=01ff
 701 Ret  KERNEL.52: FREEPROCINSTANCE() retval=0x0001 ret=01f7:1460 ds=01ff
 702 Call USER.1: MESSAGEBOX(0x0000,0x01ff1246 "Runtime error 219 at 0004:1056.",0x00000000,0x1010) ret=01f7:2160 ds=01ff
 703               </programlisting>
 704             </para>
 705             <para>
 706               I think that the call to <function>MessageBox()</function>
 707               in this example is <emphasis>not</emphasis> caused by a
 708               wrong result value of some previously executed function
 709               (it's happening quite often like that), but instead the
 710               messagebox complains about a runtime error at
 711               <literal>0x0004:0x1056</literal>.
 712             </para>
 713             <para>
 714               As the segment value of the address is only
 715               <literal>4</literal>, I think that that is only an internal
 716               program value. But the offset address reveals something
 717               quite interesting: Offset <literal>1056</literal> is
 718               <emphasis>very</emphasis> close to the return address of
 719               <function>FREELIBRARY()</function>:
 720               <programlisting>
 721 Call KERNEL.96: FREELIBRARY(0x031f) ret=01cf:105c ds=01ff
 722                                              ^^^^
 723               </programlisting>
 724             </para>
 725             <para>
 726               Provided that segment <literal>0x0004</literal> is indeed segment
 727               <literal>0x1cf</literal>, we now we can use IDA                 (available at
 728               <ulink url="http://www.filelibrary.com:8080/cgi-bin/freedownload/DOS/h/72/ida35bx.zip">
 729                http://www.filelibrary.com:8080/cgi-bin/freedownload/DOS/h/72/ida35bx.zip</ulink>) to
 730               disassemble the part that caused the error. We just have to find the address of
 731               the call to <function>FreeLibrary()</function>. Some lines before that the
 732               runtime error occurred. But be careful! In some cases you don't have to
 733               disassemble the main program, but instead some DLL called by it in order to find
 734               the correct place where the runtime error occurred. That can be determined by
 735               finding the origin of the segment value (in this case <literal>0x1cf</literal>).
 736             </para>
 737           </listitem>
 738           <listitem>
 739             <para>
 740               If you have created a relay file of some crashing
 741               program and want to set a breakpoint at a certain
 742               location which is not yet available as the program loads
 743               the breakpoint's segment during execution, you may set a
 744               breakpoint to <function>GetVersion16/32</function> as
 745               those functions are called very often.
 746             </para>
 747             <para>
 748               Then do a <userinput>c</userinput> until you are able to
 749               set this breakpoint without error message.
 750             </para>
 751           </listitem>
 752           <listitem>
 753             <para>
 754               Some useful programs:
 755             </para>
 756             <variablelist>
 757               <varlistentry>
 758                 <term>
 759                   <application>IDA</application>:
 760                   <filename>
 761                     <ulink url="http://www.filelibrary.com:8080/cgi-bin/freedownload/DOS/h/72/ida35bx.zip">
 762                      http://www.filelibrary.com:8080/cgi-bin/freedownload/DOS/h/72/ida35bx.zip</ulink>
 763                   </filename>
 764                 </term>
 765                 <listitem>
 766                   <para>
 767                     <emphasis>Very</emphasis> good DOS disassembler ! It's badly needed
 768                     for debugging Wine sometimes.
 769                   </para>
 770                 </listitem>
 771               </varlistentry>
 772               <varlistentry>
 773                 <term>
 774                   <application>XRAY</application>:
 775                   <filename>
 776                     <ulink url="http://garbo.uwasa.fi/pub/pc/sysinfo/xray15.zip">
 777                      http://garbo.uwasa.fi/pub/pc/sysinfo/xray15.zip</ulink>
 778                   </filename>
 779                 </term>
 780                 <listitem>
 781                   <para>
 782                     Traces DOS calls (Int 21h, DPMI, ...). Use it with
 783                     Windows to correct file management problems etc.
 784                   </para>
 785                 </listitem>
 786               </varlistentry>
 787               <varlistentry>
 788                 <term>
 789                   <application>pedump</application>:
 790                   <filename>
 791                     <ulink url="ftp://ftp.simtel.net/pub/simtelnet/win95/prog/pedump.zip">
 792                      ftp://ftp.simtel.net/pub/simtelnet/win95/prog/pedump.zip</ulink>
 793                   </filename>
 794                 </term>
 795                 <listitem>
 796                   <para>
 797                     Dumps the imports and exports of a PE (Portable
 798                     Executable) DLL.
 799                   </para>
 800                 </listitem>
 801               </varlistentry>
 802               <varlistentry>
 803                 <term>
 804                   <application>winedump</application>:
 805                 </term>
 806                 <listitem>
 807                   <para>
 808                     Dumps the imports and exports of a PE (Portable
 809                     Executable) DLL (included in wine tree).
 810                   </para>
 811                 </listitem>
 812               </varlistentry>
 813             </variablelist>
 814           </listitem>
 815         </itemizedlist>
 816       </sect2>
 817
 818       <sect2>
 819         <title>Some basic debugger usages:</title>
 820
 821         <para>
 822           After starting your program with
 823         </para>
 824         <screen>
 825 wine -debug myprog.exe
 826         </screen>
 827         <para>
 828           the program loads and you get a prompt at the program
 829           starting point. Then you can set breakpoints:
 830         </para>
 831         <screen>
 832   b RoutineName      (by outine name) OR
 833   b *0x812575        (by address)
 834         </screen>
 835         <para>
 836           Then you hit <command>c</command> (continue) to run the
 837           program. It stops at the breakpoint. You can type
 838         </para>
 839         <screen>
 840   step               (to step one line) OR
 841   stepi              (to step one machine instruction at a time;
 842                       here, it helps to know the basic 386
 843                       instruction set)
 844   info reg           (to see registers)
 845   info stack         (to see hex values in the stack)
 846   info local         (to see local variables)
 847   list &lt;line number&gt; (to list source code)
 848   x &lt;variable name&gt;  (to examine a variable; only works if code
 849                       is not compiled with optimization)
 850   x 0x4269978        (to examine a memory location)
 851   ?                  (help)
 852   q                  (quit)
 853         </screen>
 854         <para>
 855           By hitting <keycap>Enter</keycap>, you repeat the last
 856           command.
 857         </para>
 858       </sect2>
 859     </sect1>
 860
 861
 862     <sect1 id="memory-addresses">
 863       <title>Useful memory addresses</title>
 864       <para>
 865         Wine uses several different kinds of memory addresses.
 866       </para>
 867       <variablelist>
 868         <varlistentry>
 869           <term>
 870             Win32/"normal" Wine addresses/Linux: linear addresses.
 871           </term>
 872           <listitem>
 873             <para>
 874               Linear addresses can be everything from 0x0 up to
 875               0xffffffff.  In Wine on Linux they are often around
 876               e.g. 0x08000000, 0x00400000 (std. Win32 program load
 877               address), 0x40000000.  Every Win32 process has its own
 878               private 4GB address space (that is, from 0x0 up to
 879               0xffffffff).
 880             </para>
 881           </listitem>
 882         </varlistentry>
 883         <varlistentry>
 884           <term>
 885             Win16 "enhanced mode": segmented addresses.
 886           </term>
 887           <listitem>
 888             <para>
 889               These are the "normal" Win16 addresses, called SEGPTR.
 890               They have a segment:offset notation, e.g. 0x01d7:0x0012.
 891               The segment part usually is a "selector", which
 892               <emphasis>always</emphasis>
 893               has the lowest 3 bits set.  Some sample selectors are
 894               0x1f7, 0x16f, 0x8f.  If these bits are set except for
 895               the lowest bit, as e.g. with 0x1f6,xi then it might be a
 896               handle to global memory. Just set the lowest bit to get
 897               the selector in these cases.  A selector kind of
 898               "points" to a certain linear (see above) base address.
 899               It has more or less three important attributes: segment
 900               base address, segment limit, segment access rights.
 901             </para>
 902             <para>
 903               Example:
 904             </para>
 905             <para>
 906               Selector 0x1f7 (0x40320000, 0x0000ffff, r-x) So 0x1f7
 907               has a base address of 0x40320000, the segment's last
 908               address is 0x4032ffff (limit 0xffff), and it's readable
 909               and executable.  So an address of 0x1f7:0x2300 would be
 910               the linear address of 0x40322300.
 911             </para>
 912           </listitem>
 913         </varlistentry>
 914         <varlistentry>
 915           <term>
 916             DOS/Win16 "standard mode"
 917           </term>
 918           <listitem>
 919             <para>
 920               They, too, have a segment:offset notation.  But they are
 921               completely different from "normal" Win16 addresses, as
 922               they just represent at most 1MB of memory: The segment
 923               part can be anything from 0 to 0xffff, and it's the same
 924               with the offset part.
 925             </para>
 926             <para>
 927               Now the strange thing is the calculation that's behind
 928               these addresses: Just calculate segment*16 + offset in
 929               order to get a "linear DOS" address.  So
 930               e.g. 0x0f04:0x3628 results in 0xf040 + 0x3628 = 0x12668.
 931               And the highest address you can get is 0xfffff (1MB), of
 932               course.  In Wine, this "linear DOS" address of 0x12668
 933               has to be added to the linear base address of the
 934               corresponding DOS memory allocated for dosmod in order
 935               to get the true linear address of a DOS seg:offs
 936               address.  And make sure that you're doing this in the
 937               correct process with the correct linear address space,
 938               of course ;-)
 939             </para>
 940           </listitem>
 941         </varlistentry>
 942       </variablelist>
 943     </sect1>
 944
 945     <sect1 id="dbg-config">
 946       <title>Configuration</title>
 947
 948       <sect2>
 949         <title>Registry configuration</title>
 950
 951         <para>
 952           The Windows' debugging API uses a registry entry to know
 953           which debugger to invoke when an unhandled exception occurs
 954           (see <link endterm="dbg-exception-title"
 955           linkend="dbg-on-exception"></link> for some details). Two
 956           values in key
 957         </para>
 958         <programlisting>
 959 "MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\AeDebug"
 960         </programlisting>
 961         <para>
 962           Determine the behavior:
 963         </para>
 964         <variablelist>
 965           <varlistentry>
 966             <term>Debugger:</term>
 967             <listitem>
 968               <para>
 969                 this is the command line used to launch the debugger
 970                 (it uses two <function>printf</function> formats
 971                 (<literal>%ld</literal>) to pass context dependent
 972                 information to  the debugger). You should put here a
 973                 complete path to your debugger
 974                 (<command>WineDbg</command> can of course be used, but
 975                 any other Windows' debugging API aware debugger will
 976                 do).
 977                 The path to the debugger you chose to use must be reachable
 978                 via a DOS drive in the Wine config file !
 979               </para>
 980             </listitem>
 981           </varlistentry>
 982           <varlistentry>
 983             <term>Auto:</term>
 984             <listitem>
 985               <para>
 986                 if this value is zero, a message box will ask the
 987                 user if he/she wishes to launch the debugger when an
 988                 unhandled exception occurs. Otherwise, the debugger
 989                 is automatically started.
 990               </para>
 991             </listitem>
 992           </varlistentry>
 993         </variablelist>
 994
 995         <para>
 996           A regular Wine registry looks like:
 997         </para>
 998         <programlisting>
 999 [MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\AeDebug] 957636538
1000 "Auto"=dword:00000001
1001 "Debugger"="winedbg %ld %ld"
1002         </programlisting>
1003
1004         <note>
1005           <title>Note 1</title>
1006           <para>
1007             creating this key is mandatory. Not doing so will not
1008             fire the debugger when an exception occurs.
1009           </para>
1010         </note>
1011         <note>
1012           <title>Note 2</title>
1013           <para>
1014             <command>wineinstall</command> (available in Wine source)
1015             sets up this correctly.
1016             However, due to some limitation of the registry installed,
1017             if a previous Wine installation exists, it's safer to
1018             remove the whole
1019           </para>
1020           <programlisting>
1021 [MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\AeDebug]
1022           </programlisting>
1023           <para>
1024             key before running again <command>wineinstall</command> to
1025             regenerate this key.
1026           </para>
1027         </note>
1028       </sect2>
1029
1030       <sect2>
1031         <title>WineDbg configuration</title>
1032
1033         <para>
1034           <command>WineDbg</command> can be configured through a number
1035           of options. Those options are stored in the registry, on a
1036           per user basis. The key is (in <emphasis>my</emphasis> registry)
1037         </para>
1038         <programlisting>
1039 [eric\\Software\\Wine\\WineDbg]
1040         </programlisting>
1041         <para>
1042           Those options can be read/written while inside
1043           <command>WineDbg</command>, as part of the debugger
1044           expressions. To refer to one of these options, its name must
1045           be  prefixed by a <literal>$</literal> sign. For example,
1046         </para>
1047         <programlisting>
1048 set $BreakAllThreadsStartup = 1
1049         </programlisting>
1050         <para>
1051           sets the option <varname>BreakAllThreadsStartup</varname> to
1052           <literal>TRUE</literal>.
1053         </para>
1054         <para>
1055           All the options are read from the registry when
1056           <command>WineDbg</command> starts (if no corresponding value
1057           is found, a default value is used), and are written back to
1058           the registry when <command>WineDbg</command> exits (hence,
1059           all modifications to those options are automatically saved
1060           when <command>WineDbg</command> terminates).
1061         </para>
1062         <para>
1063           Here's the list of all options:
1064         </para>
1065
1066         <sect3>
1067           <title>Controlling when the debugger is entered</title>
1068
1069           <variablelist>
1070             <varlistentry>
1071               <term><varname>BreakAllThreadsStartup</varname></term>
1072               <listitem>
1073                 <para>
1074                   Set to <literal>TRUE</literal> if at all threads
1075                   start-up the debugger stops  set to
1076                   <literal>FALSE</literal> if only at the first thread
1077                   startup of a given process the debugger stops.
1078                   <literal>FALSE</literal> by default.
1079                 </para>
1080               </listitem>
1081             </varlistentry>
1082             <varlistentry>
1083               <term><varname>BreakOnCritSectTimeOut</varname></term>
1084               <listitem>
1085                 <para>
1086                   Set to <literal>TRUE</literal> if the debugger stops
1087                   when a critical section times out (5 minutes);
1088                   <literal>TRUE</literal> by default.
1089                 </para>
1090               </listitem>
1091             </varlistentry>
1092             <varlistentry>
1093               <term><varname>BreakOnAttach</varname></term>
1094               <listitem>
1095                 <para>
1096                   Set to <literal>TRUE</literal> if when
1097                   <command>WineDbg</command> attaches to an existing
1098                   process after an unhandled exception,
1099                   <command>WineDbg</command> shall be entered on the
1100                   first attach event. Since the attach event is
1101                   meaningless in the context of an exception event
1102                   (the next event  which is the exception event is of
1103                   course relevant), that option is likely to be
1104                   <literal>FALSE</literal>.
1105                 </para>
1106               </listitem>
1107             </varlistentry>
1108             <varlistentry>
1109               <term><varname>BreakOnFirstChance</varname></term>
1110               <listitem>
1111                 <para>
1112                   An exception can generate two debug events. The
1113                   first one is passed to the debugger (known as a
1114                   first chance) just after the exception. The debugger
1115                   can then decides either to resume execution (see
1116                   <command>WineDbg</command>'s <command>cont</command>
1117                   command) or pass the exception up to the exception
1118                   handler chain in the program (if it exists)
1119                   (<command>WineDbg</command> implements this through the
1120                   <command>pass</command> command). If none of the
1121                   exception handlers takes care of the exception, the
1122                   exception event is sent again to the debugger (known
1123                   as last chance exception). You cannot pass on a last
1124                   exception. When the
1125                   <varname>BreakOnFirstChance</varname> exception is
1126                   <literal>TRUE</literal>, then winedbg is entered for
1127                   both first and last chance execptions (to
1128                   <literal>FALSE</literal>, it's only entered for last
1129                   chance exceptions).
1130                 </para>
1131               </listitem>
1132             </varlistentry>
1133             <varlistentry>
1134               <term><varname>BreakOnDllLoad</varname></term>
1135               <listitem>
1136                 <para>
1137                   Set to <literal>TRUE</literal> if the debugger stops
1138                   when a DLL is loaded into memory; when the debugger
1139                   is invoked after a crash, the DLLs already mapped in
1140                   memory will not trigger this break.
1141                   <literal>FALSE</literal> by default.
1142                 </para>
1143               </listitem>
1144             </varlistentry>
1145           </variablelist>
1146         </sect3>
1147
1148         <sect3>
1149           <title>Context information</title>
1150
1151           <variablelist>
1152             <varlistentry>
1153               <term><varname>ThreadId</varname></term>
1154               <listitem>
1155                 <para>
1156                   ID of the <varname>W-thread</varname> currently
1157                   examined by the debugger
1158                 </para>
1159               </listitem>
1160             </varlistentry>
1161             <varlistentry>
1162               <term><varname>ProcessId</varname></term>
1163               <listitem>
1164                 <para>
1165                   ID of the <varname>W-thread</varname> currently
1166                   examined by the debugger
1167                 </para>
1168               </listitem>
1169             </varlistentry>
1170             <varlistentry>
1171               <term>&lt;registers></term>
1172               <listitem>
1173                 <para>
1174                   All CPU registers are also available
1175                 </para>
1176               </listitem>
1177             </varlistentry>
1178           </variablelist>
1179
1180           <para>
1181             The <varname>ThreadId</varname> and
1182             <varname>ProcessId</varname> variables can be handy to set
1183             conditional breakpoints on a given thread or process.
1184           </para>
1185         </sect3>
1186       </sect2>
1187     </sect1>
1188
1189
1190     <sect1 id="dbg-commands">
1191       <title>WineDbg Command Reference</title>
1192
1193       <sect2>
1194         <title>Misc</title>
1195
1196         <screen>
1197 abort           aborts the debugger
1198 quit            exits the debugger
1199
1200 attach N        attach to a W-process (N is its ID, numeric or hexadecimal(0xN)).
1201                 IDs can be obtained using the walk process command.  Note the
1202                 walk process command returns hexadecimal values
1203 detach          detach from a W-process. WineDbg will exit (this may
1204                 be changed later on)
1205         </screen>
1206         <screen>
1207 help            prints some help on the commands
1208 help info       prints some help on info commands
1209         </screen>
1210         <screen>
1211 mode 16         switch to 16 bit mode
1212 mode 32         switch to 32 bit mode
1213         </screen>
1214       </sect2>
1215
1216       <sect2>
1217         <title>Flow control</title>
1218
1219         <screen>
1220 cont            continue execution until next breakpoint or exception.
1221 pass            pass the exception event up to the filter chain.
1222 step            continue execution until next C line of code (enters
1223                 function call)
1224 next            continue execution until next C line of code (doesn't
1225                 enter function call)
1226 stepi           execute next assembly instruction (enters function
1227                 call)
1228 nexti           execute next assembly instruction (doesn't enter
1229                 function call)
1230 finish          do nexti commands until current function is exited
1231         </screen>
1232         <para>
1233           cont, step, next, stepi, nexti can be postfixed by a
1234           number (N), meaning that the command must be executed N
1235           times.
1236         </para>
1237       </sect2>
1238
1239       <sect2>
1240         <title>Breakpoints, watch points</title>
1241
1242         <screen>
1243 enable N        enables (break|watch)point #N
1244 disable N       disables (break|watch)point #N
1245 delete N        deletes  (break|watch)point #N
1246 cond N          removes any a existing condition to (break|watch)point N
1247 cond N &lt;expr&gt;     adds condition &lt;expr&gt; to (break|watch)point N. &lt;expr&gt;
1248                 will be evaluated each time the breakpoint is hit. If
1249                 the result is a zero value, the breakpoint isn't
1250                 triggered
1251 break * N       adds a breakpoint at address N
1252 break &lt;id&gt;        adds a breakpoint at the address of symbol &lt;id&gt;
1253 break &lt;id&gt; N      adds a breakpoint at the address of symbol &lt;id&gt; (N ?)
1254 break N         adds a breakpoint at line N of current source file
1255 break           adds a breakpoint at current $pc address
1256 watch * N       adds a watch command (on write) at address N (on 4 bytes)
1257 watch &lt;id&gt;        adds a watch command (on write) at the address of
1258                 symbol &lt;id&gt;
1259 info break      lists all (break|watch)points (with state)
1260         </screen>
1261         <para>
1262           When setting a breakpoint on an &lt;id&gt;, if several symbols with this
1263           &lt;id&gt; exist, the debugger will prompt for the symbol you want to use.
1264           Pick up the one you want from its number.
1265         </para>
1266         <para>
1267           Alternatively you can specify a DLL in the &lt;id&gt; (for example
1268           MYDLL.DLL.myFunc for function myFunc of
1269           <filename>G:\AnyPath\MyDll.dll)</filename>.
1270         </para>
1271         <para>
1272           You can use the symbol <emphasis>EntryPoint</emphasis> to stand for
1273           the entry point of the Dll.
1274         </para>
1275         <para>
1276           When setting a break/watch-point by &lt;id&gt;, if the symbol cannot be found (for example, the symbol is contained in a not yet loaded module), winedbg will
1277           recall the name of the symbol and will try to set the breakpoint each time a new module is loaded (until it succeeds).
1278         </para>
1279       </sect2>
1280
1281       <sect2>
1282         <title>Stack manipulation</title>
1283
1284         <screen>
1285 bt              print calling stack of current thread
1286 bt N            print calling stack of thread of ID N (note: this
1287                 doesn't change the position of the current frame as
1288                 manipulated by the up & dn commands)
1289 up              goes up one frame in current thread's stack
1290 up N            goes up N frames in current thread's stack
1291 dn              goes down one frame in current thread's stack
1292 dn N            goes down N frames in current thread's stack
1293 frame N         set N as the current frame for current thread's stack
1294 info local      prints information on local variables for current
1295                 function
1296         </screen>
1297       </sect2>
1298
1299       <sect2>
1300         <title>Directory & source file manipulation</title>
1301
1302         <screen>
1303 show dir
1304 dir &lt;pathname&gt;
1305 dir
1306 symbolfile &lt;pathname&gt;   loads external symbol definition
1307 symbolfile &lt;pathname&gt; N loads external symbol definition
1308                            (applying an offset of N to addresses)
1309         </screen>
1310         <screen>
1311 list            lists 10 source lines from current position
1312 list -          lists 10 source lines before current position
1313 list N          lists 10 source lines from line N in current file
1314 list &lt;path&gt;:N     lists 10 source lines from line N in file &lt;path&gt;
1315 list &lt;id&gt; lists 10 source lines of function &lt;id&gt;
1316 list * N        lists 10 source lines from address N
1317         </screen>
1318         <para>
1319           You can specify the end target (to change the 10 lines
1320           value) using the ','. For example:
1321         </para>
1322         <screen>
1323 list 123, 234   lists source lines from line 123 up to line 234 in
1324                 current file
1325 list foo.c:1,56 lists source lines from line 1 up to 56 in file foo.c
1326         </screen>
1327       </sect2>
1328
1329       <sect2>
1330         <title>Displaying</title>
1331
1332         <para>
1333           A display is an expression that's evaluated and printed
1334           after the execution of any <command>WineDbg</command>
1335           command.
1336         </para>
1337         <screen>
1338 display         lists the active displays
1339 info display    (same as above command)
1340 display &lt;expr&gt;    adds a display for expression &lt;expr&gt;
1341 display /fmt &lt;expr&gt;       adds a display for expression &lt;expr&gt;. Printing
1342                 evaluated &lt;expr&gt; is done using the given format (see
1343                 print command for more on formats)
1344 del display N   deletes display #N
1345 undisplay N     (same as del display)
1346         </screen>
1347       </sect2>
1348
1349       <sect2>
1350         <title>Disassembly</title>
1351
1352         <screen>
1353 disas           disassemble from current position
1354 disas &lt;expr&gt;      disassemble from address &lt;expr&gt;
1355 disas &lt;expr&gt;,&lt;expr&gt;disassembles code between addresses specified by
1356                 the two &lt;expr&gt;
1357         </screen>
1358       </sect2>
1359
1360       <sect2>
1361         <title>Information on Wine's internals</title>
1362
1363         <screen>
1364 info class &lt;id&gt; prints information on Windows's class &lt;id&gt;
1365 walk class      lists all Windows' class registered in Wine
1366 info share      lists all the dynamic libraries loaded the debugged
1367                 program (including .so files, NE and PE DLLs)
1368 info module &lt;N&gt; prints information on module of handle &lt;N&gt;
1369 walk module     lists all modules loaded by debugged program
1370 info regs       prints the value of CPU register
1371 info segment &lt;N&gt;prints information on segment &lt;N&gt;
1372 info segment    lists all allocated segments
1373 info stack      prints the values on top of the stack
1374 walk map        lists all virtual mappings used by the debugged
1375                 program
1376 walk map &lt;N&gt;    lists all virtual mappings used by the program of pid &lt;N&gt;
1377 info wnd &lt;N&gt;    prints information of Window of handle &lt;N&gt;
1378 walk wnd        lists all the window hierarchy starting from the
1379                 desktop window
1380 walk wnd &lt;N&gt;    lists all the window hierarchy starting from the
1381                 window of handle &lt;N&gt;
1382 walk process    lists all w-processes in Wine session
1383 walk thread     lists all w-threads in Wine session
1384 walk exception  lists the exception frames (starting from current
1385                 stack frame)
1386         </screen>
1387       </sect2>
1388
1389       <sect2>
1390         <title>Memory (reading, writing, typing)</title>
1391
1392         <screen>
1393 x &lt;expr&gt;  examines memory at &lt;expr&gt; address
1394 x /fmt &lt;expr&gt;     examines memory at &lt;expr&gt; address using format /fmt
1395 print &lt;expr&gt;      prints the value of &lt;expr&gt; (possibly using its type)
1396 print /fmt &lt;expr&gt; prints the value of &lt;expr&gt; (possibly using its
1397                 type)
1398 set &lt;lval&gt;=&lt;expr&gt;   writes the value of &lt;expr&gt; in &lt;lval&gt;
1399 whatis &lt;expr&gt;     prints the C type of expression &lt;expr&gt;
1400         </screen>
1401         <para>
1402           <filename>/fmt</filename> is either <filename>/&lt;letter&gt;</filename> or
1403           <filename>/&lt;count&gt;&lt;letter&gt;</filename> letter can be
1404         </para>
1405         <screen>
1406 s =&gt; an ASCII string
1407 u =&gt; an Unicode UTF16 string
1408 i =&gt; instructions (disassemble)
1409 x =&gt; 32 bit unsigned hexadecimal integer
1410 d =&gt; 32 bit signed decimal integer
1411 w =&gt; 16 bit unsigned hexadecimal integer
1412 c =&gt; character (only printable 0x20-0x7f are actually printed)
1413 b =&gt; 8 bit unsigned hexadecimal integer
1414 g =&gt; GUID
1415         </screen>
1416       </sect2>
1417
1418       <sect2>
1419         <title>Expressions</title>
1420
1421         <para>
1422           Expressions in Wine Debugger are mostly written in a C form. However, there
1423           are a few discrepancies:
1424           <itemizedlist>
1425             <listitem>
1426               <para>
1427                 Identifiers can take a '.' in their names. This allow
1428                 mainly to access symbols from different DLLs like
1429                 <function>USER32.DLL.CreateWindowA</function>.
1430               </para>
1431             </listitem>
1432             <listitem>
1433               <para>
1434                 The debugger will try to distinguish this writing with structure operations.
1435                 Therefore, you can only use the previous writing in operations manipulating
1436                 symbols ({break|watch}points, type information command...).
1437               </para>
1438             </listitem>
1439           </itemizedlist>
1440         </para>
1441       </sect2>
1442       <sect2>
1443           <title>Debug channels</title>
1444               <para>
1445                It is possible to turn on and off debug messages as you are debugging using
1446                the set command.
1447               </para>
1448             <screen>
1449 set + warn win  =&gt; turn on warn on 'win' channel
1450 set + win       =&gt; turn on warn/fixme/err/trace on 'win' channel
1451 set - win       =&gt; turn off warn/fixme/err/trace on 'win' channel
1452 set - fixme     =&gt; turn off the 'fixme' class
1453             </screen>
1454       </sect2>
1455
1456     </sect1>
1457
1458     <sect1 id="dbg-others">
1459       <title>Other debuggers</title>
1460
1461       <sect2>
1462         <title>GDB mode</title>
1463
1464         <para>
1465           WineDbg can act as a remote monitor for GDB. This allows to
1466           use all the power of GDB, but while debugging wine and/or
1467           any Win32 application. To enable this mode, just add
1468           <parameter>--gdb</parameter> to winedbg command line. You'll
1469           end up on a GDB prompt. You'll have to use the GDB commands
1470           (not the wine nes).
1471         </para>
1472
1473         <para>
1474           However, some limitation in GDB while debugging wine (see
1475           below) don't appear in this mode:
1476           <itemizedlist>
1477             <listitem>
1478               <para>
1479                 GDB will correctly present Win32 thread
1480                 information and breakpoint behavior
1481               </para>
1482             </listitem>
1483             <listitem>
1484               <para>
1485                 Moreover, it also provides support for the Dwarf II
1486                 debug format (which became the default format (instead
1487                 of stabs) in gcc 3.1).
1488               </para>
1489             </listitem>
1490           </itemizedlist>
1491         </para>
1492
1493         <para>
1494           A few wine extensions available through the monitor command.
1495 <screen>
1496 monitor wnd           lists all window in the Wine session
1497 monitor proc          lists all processes in the Wine session
1498 monitor mem           displays memory mapping of debugged process
1499                       (doesn't work)
1500 </screen>
1501         </para>
1502       </sect2>
1503
1504       <sect2>
1505         <title>Graphical frontends to gdb</title>
1506
1507         <para>
1508           This section will describe how you can debug wine using the
1509           GDB mode of winedbg and some graphical front ends to GDB for
1510           those of you who really like graphical debuggers.
1511         </para>
1512
1513         <sect3>
1514           <title>DDD</title>
1515
1516           <para>
1517             Use the following steps, in this order:
1518 <orderedlist>
1519               <listitem>
1520                 <para>
1521 Start the wine debugger with a command line
1522 like:
1523 <screen>
1524         winedbg -- --gdb --no-start &lt;name_of_exe_to_debug.exe&gt;
1525 </screen>
1526 </para>
1527               </listitem>
1528               <listitem>
1529                 <para>
1530                   Start ddd
1531                 </para>
1532               </listitem>
1533               <listitem>
1534                 <para>
1535                   In ddd, use the 'Open File' or 'Open Program' to
1536                   point to the wine executable
1537                 </para>
1538               </listitem>
1539               <listitem>
1540                 <para>
1541 In the output of 1/, there's a line like
1542 <screen>
1543         target remote localhost:32878
1544 </screen>
1545 copy that line and paste into ddd command pane (the one with the (gdb)
1546 prompt)
1547 </para>
1548               </listitem>
1549             </orderedlist>
1550 The program should now be loaded and up and running. If you want, you
1551 can also add in 1/ after the name of the exec all the needed
1552 parameters
1553           </para>
1554         </sect3>
1555         <sect3>
1556           <title>kdbg</title>
1557
1558           <para>
1559             Use the following steps, in this order:
1560             <orderedlist>
1561               <listitem>
1562                 <para>
1563                   Start the wine debugger with a command line like:
1564 <screen>
1565         winedbg -- --gdb --no-start &lt;name_of_exe_to_debug.exe&gt;
1566 </screen>
1567 </para>
1568               </listitem>
1569               <listitem>
1570                 <para>
1571                   In the output of 1/, there's a line like
1572 <screen>
1573         target remote localhost:32878
1574 </screen>
1575 Start kdbg with
1576 <screen>
1577 kdbg -r localhost:32878 wine
1578 </screen>
1579 localhost:32878 is not a fixed value, but has been printed in step
1580 1/. 'wine' should also be the full path to the wine executable.
1581 </para>
1582               </listitem>
1583             </orderedlist>
1584 The program should now be loaded and up and running. If you want, you
1585 can also add in 1/ after the name of the exec all the needed
1586 parameters
1587           </para>
1588         </sect3>
1589       </sect2>
1590
1591       <sect2>
1592         <title>Using other Unix debuggers</title>
1593
1594         <para>
1595           You can also use other debuggers (like
1596           <command>gdb</command>), but you must be aware of a few
1597           items:
1598         </para>
1599         <para>
1600           You need to attach the unix debugger to the correct unix
1601           process (representing the correct windows thread) (you can
1602           "guess" it from a <command>ps fax</command> for example:
1603           When running the emulator, usually the first two
1604           <varname>upids</varname> are for the Windows' application
1605           running the desktop, the first thread of the application is
1606           generally the third <varname>upid</varname>; when running a
1607           Winelib program, the first thread of the application is
1608           generally the first <varname>upid</varname>)
1609         </para>
1610         <note>
1611           <para>
1612             Even if latest <command>gdb</command> implements the
1613             notion of threads, it won't work with Wine because the
1614             thread abstraction used for implementing Windows' thread
1615             is not 100% mapped onto the Linux POSIX threads
1616             implementation. It means that you'll have to spawn a
1617             different <command>gdb</command> session for each Windows'
1618             thread you wish to debug.
1619           </para>
1620         </note>
1621
1622         <para>
1623           Here's how to get info about the current execution status of a
1624           certain Wine process:
1625         </para>
1626         <para>
1627           Change into your Wine source dir and enter:
1628         </para>
1629         <screen>
1630 $ gdb wine
1631         </screen>
1632         <para>
1633           Switch to another console and enter <command>ps ax | grep
1634             wine</command> to find all wine processes. Inside
1635           <command>gdb</command>, repeat for all Wine processes:
1636         </para>
1637         <screen>
1638 (gdb) attach <userinput>PID</userinput>
1639         </screen>
1640         <para>
1641           with <userinput>PID</userinput> being the process ID of one of
1642           the Wine processes.  Use
1643         </para>
1644         <screen>
1645 (gdb) bt
1646         </screen>
1647         <para>
1648           to get the backtrace of the current Wine process, i.e. the
1649           function call history.  That way you can find out what the
1650           current process is doing right now.  And then you can use
1651           several times:
1652         </para>
1653         <screen>
1654 (gdb) n
1655         </screen>
1656         <para>
1657           or maybe even
1658         </para>
1659         <screen>
1660 (gdb) b <userinput>SomeFunction</userinput>
1661         </screen>
1662         <para>
1663           and
1664         </para>
1665         <screen>
1666 (gdb) c
1667         </screen>
1668         <para>
1669           to set a breakpoint at a certain function and continue up to
1670           that function.  Finally you can enter
1671         </para>
1672         <screen>
1673 (gdb) detach
1674         </screen>
1675         <para>
1676           to detach from the Wine process.
1677         </para>
1678         <!-- *** End of xtra content *** -->
1679       </sect2>
1680
1681       <sect2>
1682         <title>Using other Windows debuggers</title>
1683
1684         <para>
1685           You can use any Windows' debugging API compliant debugger
1686           with Wine. Some reports have been made of success with
1687           VisualStudio debugger (in remote mode, only the hub runs
1688           in Wine). GoVest fully runs in Wine.
1689         </para>
1690       </sect2>
1691
1692       <sect2>
1693         <title>Main differences between winedbg and regular Unix debuggers</title>
1694         <table><title>Debuggers comparison</title>
1695           <tgroup cols=2 align="left">
1696             <tbody>
1697               <row>
1698                 <entry>WineDbg</entry><entry>gdb</entry>
1699               </row>
1700               <row>
1701                 <entry>
1702                   WineDbg debugs a Windows' process: the various
1703                   threads will be handled by the same WineDbg session,
1704                   and a breakpoint will be triggered for any thread of
1705                   the W-process
1706                 </entry>
1707                 <entry>
1708                   gdb debugs a Windows' thread: a separate gdb session
1709                   is needed for each thread of a Windows' process and
1710                   a breakpoint will be triggered only for the w-thread
1711                   debugged
1712                 </entry>
1713               </row>
1714               <row>
1715                 <entry>
1716                   WineDbg supports debug information from stabs
1717                   (standard Unix format) and Microsoft's C, CodeView,
1718                   .DBG
1719                 </entry>
1720                 <entry>
1721                   GDB supports debug information from stabs (standard
1722                   Unix format) and Dwarf II.
1723                 </entry>
1724               </row>
1725             </tbody>
1726           </tgroup>
1727         </table>
1728       </sect2>
1729     </sect1>
1730
1731
1732     <sect1 id="dbg-limits">
1733       <title>Limitations</title>
1734
1735       <itemizedlist>
1736         <listitem>
1737           <para>
1738             16 bit processes are not supported (but calls to 16 bit
1739             code in 32 bit  applications are).
1740           </para>
1741         </listitem>
1742         <listitem>
1743           <para>
1744             Function call in expression is no longer supported
1745           </para>
1746         </listitem>
1747       </itemizedlist>
1748     </sect1>
1749   </chapter>
1750
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