documentation/debugger.sgml

   1   <chapter id="debugger">
   2     <title>Debugging Wine</title>
   3
   4     <sect1 id="dbg-intro">
   5       <title>Introduction</title>
   6
   7       <para>
   8         Written by &name-eric-pouech; <email>&email-eric-pouech;</email>
   9         (Last updated: 9/15/2002)
  10       </para>
  11       <para>
  12         (Extracted from <filename>wine/documentation/winedbg</filename>)
  13       </para>
  14
  15       <sect2>
  16         <title>Processes and threads: in underlying OS and in Windows</title>
  17
  18         <para>
  19           Before going into the depths of debugging in Wine, here's
  20           a small overview of process and thread handling in Wine.
  21           It has to be clear that there are two different beasts:
  22           processes/threads from the Unix point of view and
  23           processes/threads from a Windows point of view.
  24         </para>
  25         <para>
  26           Each Windows' thread is implemented as a Unix process (under
  27           Linux using the <function>clone</function> syscall), meaning
  28           that all threads of a same Windows' process share the same
  29           (unix) address space.
  30         </para>
  31         <para>
  32           In the following:
  33         </para>
  34         <itemizedlist>
  35           <listitem>
  36             <para><varname>W-process</varname> means a process in Windows' terminology</para>
  37           </listitem>
  38           <listitem>
  39             <para><varname>U-process</varname> means a process in Unix' terminology</para>
  40           </listitem>
  41           <listitem>
  42             <para><varname>W-thread</varname> means a thread in Windows' terminology</para>
  43           </listitem>
  44         </itemizedlist>
  45         <para>
  46           A <varname>W-process</varname> is made of one or several
  47           <varname>W-threads</varname>. Each
  48           <varname>W-thread</varname> is mapped to one and only one
  49           <varname>U-process</varname>. All
  50           <varname>U-processes</varname> of a same
  51           <varname>W-process</varname> share the same address space.
  52         </para>
  53         <para>
  54           Each Unix process can be identified by two values:
  55         </para>
  56         <itemizedlist>
  57           <listitem>
  58             <para>the Unix process id (<varname>upid</varname> in the following)</para>
  59           </listitem>
  60           <listitem>
  61             <para>the Windows's thread id (<varname>tid</varname>)</para>
  62           </listitem>
  63         </itemizedlist>
  64         <para>
  65           Each Windows' process has also a Windows' process id
  66           (<varname>wpid</varname> in the following). It must be clear
  67           that <varname>upid</varname> and <varname>wpid</varname> are
  68           different and shall not be used instead of the other.
  69         </para>
  70         <para>
  71           <varname>Wpid</varname> and <varname>tid</varname> are
  72           defined (Windows) system wide. They must not be confused
  73           with process or thread handles which, as any handle, is an
  74           indirection to a system object (in this case process or
  75           thread). A same process can have several different handles
  76           on the same kernel object. The handles can be defined as
  77           local (the values is only valid in a process), or system
  78           wide (the same handle can be used by any
  79           <varname>W-process</varname>).
  80         </para>
  81       </sect2>
  82
  83       <sect2>
  84         <title>Wine, debugging and WineDbg</title>
  85
  86         <para>
  87           When talking of debugging in Wine, there are at least two
  88           levels to think of:
  89         </para>
  90         <itemizedlist>
  91           <listitem>
  92             <para>the Windows' debugging API.</para>
  93           </listitem>
  94           <listitem>
  95             <para>the Wine integrated debugger, dubbed
  96               <command>WineDbg</command>.</para>
  97           </listitem>
  98         </itemizedlist>
  99         <para>
 100           Wine implements most of the Windows' debugging API (the
 101           part in <filename>KERNEL32.DLL</filename>, not the one in
 102           <filename>IMAGEHLP.DLL</filename>), and allows any program
 103           (emulated or Winelib) using that API to debug a
 104           <varname>W-process</varname>.
 105         </para>
 106         <para>
 107           <command>WineDbg</command> is a Winelib application making
 108           use of this API to allow debugging both any Wine or Winelib
 109           applications as well as Wine itself (kernel and all DLLs).
 110         </para>
 111       </sect2>
 112     </sect1>
 113
 114
 115     <sect1 id="dbg-modes">
 116       <title>WineDbg's modes of invocation</title>
 117
 118       <sect2>
 119         <title>Starting a process</title>
 120
 121         <para>
 122           Any application (either a Windows' native executable, or a
 123           Winelib application) can be run through
 124           <command>WineDbg</command>. Command line options and tricks
 125           are the same as for wine:
 126         </para>
 127         <screen>
 128 winedbg telnet.exe
 129 winedbg "hl.exe -windowed"
 130         </screen>
 131       </sect2>
 132
 133       <sect2>
 134         <title>Attaching</title>
 135
 136         <para>
 137           <command>WineDbg</command> can also be launched without any
 138           command line argument: <command>WineDbg</command> is started
 139           without any attached process. You can get a list of running
 140           <varname>W-processes</varname> (and their
 141           <varname>wpid</varname>'s) using the <command>walk
 142             process</command> command, and then, with the
 143           <command>attach</command> command, pick up the
 144           <varname>wpid</varname> of the <varname>W-process</varname>
 145           you want to debug. This is (for now) a neat feature for the
 146           following reasons:
 147         </para>
 148         <itemizedlist>
 149           <listitem>
 150             <para>you can debug an already started application</para>
 151           </listitem>
 152         </itemizedlist>
 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...
 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 quited.
 255         </para>
 256       </sect2>
 257     </sect1>
 258
 259
 260     <sect1 id="wine-debugger">
 261       <title>Using the Wine Debugger</title>
 262
 263       <para>
 264         Written by &name-marcus-meissner; <email>&email-marcus-meissner;</email>,
 265         additions welcome.
 266       </para>
 267       <para>
 268         (Extracted from <filename>wine/documentation/debugging</filename>)
 269       </para>
 270
 271       <para>
 272         This file describes where to start debugging Wine. If at any
 273         point you get stuck and want to ask for help, please read the
 274         <emphasis>How to Report A Bug</emphasis> section of the
 275         <emphasis>Wine Users Guide</emphasis> for information on how to write
 276         useful bug reports.
 277       </para>
 278
 279       <sect2>
 280         <title>Crashes</title>
 281
 282         <para>
 283           These usually show up like this:
 284         </para>
 285         <screen>
 286 |Unexpected Windows program segfault - opcode = 8b
 287 |Segmentation fault in Windows program 1b7:c41.
 288 |Loading symbols from ELF file /root/wine/wine...
 289 |....more Loading symbols from ...
 290 |In 16 bit mode.
 291 |Register dump:
 292 | CS:01b7 SS:016f DS:0287 ES:0000
 293 | IP:0c41 SP:878a BP:8796 FLAGS:0246
 294 | AX:811e BX:0000 CX:0000 DX:0000 SI:0001 DI:ffff
 295 |Stack dump:
 296 |0x016f:0x878a:  0001 016f ffed 0000 0000 0287 890b 1e5b
 297 |0x016f:0x879a:  01b7 0001 000d 1050 08b7 016f 0001 000d
 298 |0x016f:0x87aa:  000a 0003 0004 0000 0007 0007 0190 0000
 299 |0x016f:0x87ba:
 300 |
 301 |0050: sel=0287 base=40211d30 limit=0b93f (bytes) 16-bit rw-
 302 |Backtrace:
 303 |0 0x01b7:0x0c41 (PXSRV_FONGETFACENAME+0x7c)
 304 |1 0x01b7:0x1e5b (PXSRV_FONPUTCATFONT+0x2cd)
 305 |2 0x01a7:0x05aa
 306 |3 0x01b7:0x0768 (PXSRV_FONINITFONTS+0x81)
 307 |4 0x014f:0x03ed (PDOXWIN_@SQLCURCB$Q6CBTYPEULN8CBSCTYPE+0x1b1)
 308 |5 0x013f:0x00ac
 309 |
 310 |0x01b7:0x0c41 (PXSRV_FONGETFACENAME+0x7c):  movw        %es:0x38(%bx),%dx
 311         </screen>
 312         <para>
 313           Steps to debug a crash. You may stop at any step, but please
 314           report the bug and provide as much of the information
 315           gathered to the bug report as feasible.
 316         </para>
 317
 318         <orderedlist>
 319           <listitem>
 320             <para>
 321               Get the reason for the crash. This is usually an access to
 322               an invalid selector, an access to an out of range address
 323               in a valid selector, popping a segmentregister from the
 324               stack or the like. When reporting a crash, report this
 325               <emphasis>whole</emphasis> crashdump even if it doesn't
 326               make sense to you.
 327             </para>
 328             <para>
 329               (In this case it is access to an invalid selector, for
 330               <systemitem>%es</systemitem> is <literal>0000</literal>, as
 331               seen in the register dump).
 332             </para>
 333           </listitem>
 334           <listitem>
 335             <para>
 336               Determine the cause of the crash. Since this is usually
 337               a primary/secondary reaction to a failed or misbehaving
 338               Wine function, rerun Wine with <parameter>-debugmsg
 339                 +relay</parameter> added to the commandline. This will
 340               generate quite a lot of output, but usually the reason is
 341               located in the last call(s).  Those lines usually look like
 342               this:
 343             </para>
 344             <screen>
 345 |Call KERNEL.90: LSTRLEN(0227:0692 "text") ret=01e7:2ce7 ds=0227
 346       ^^^^^^^^^  ^       ^^^^^^^^^ ^^^^^^      ^^^^^^^^^    ^^^^
 347       |          |       |         |           |            |Datasegment
 348       |          |       |         |           |Return address
 349       |          |       |         |textual parameter
 350       |          |       |
 351       |          |       |Argument(s). This one is a win16 segmented pointer.
 352       |          |Function called.
 353       |The module, the function is called in. In this case it is KERNEL.
 354
 355 |Ret  KERNEL.90: LSTRLEN() retval=0x0004 ret=01e7:2ce7 ds=0227
 356                                   ^^^^^^
 357                                   |Returnvalue is 16 bit and has the value 4.
 358             </screen>
 359           </listitem>
 360           <listitem>
 361             <para>
 362               If you have found a misbehaving function, try to find out
 363               why it misbehaves. Find the function in the source code.
 364               Try to make sense of the arguments passed. Usually there is
 365               a <function>WINE_DEFAULT_DEBUG_CHANNEL(&lt;channel>);</function>
 366               at the beginning of the file. Rerun wine with
 367               <parameter>-debugmsg +xyz,+relay</parameter> added to the
 368               commandline.
 369             </para>
 370             <para>
 371               Occasionally there are additional debug channels defined at the
 372               begining of the file in the form.
 373               <function>WINE_DECLARE_DEBUG_CHANNEL(&lt;channel>);</function>
 374               If so the offending fuction may also uses one of these alternate
 375               channels. Look through the the function for
 376              <function>TRACE_(&lt;channel>)(" ... /n");</function> and add any
 377              additional channels to the commandline.
 378             </para>
 379           </listitem>
 380           <listitem>
 381             <para>
 382               Additional information on how to debug using the internal
 383               debugger can be  found in
 384               <filename>programs/winedbg/README</filename>.
 385             </para>
 386           </listitem>
 387           <listitem>
 388             <para>
 389               If this information isn't clear enough or if you want to
 390               know more about what's happening in the function itself,
 391               try running wine with <parameter>-debugmsg
 392                 +all</parameter>, which dumps ALL included debug
 393               information in wine.
 394             </para>
 395           </listitem>
 396           <listitem>
 397             <para>
 398               If even that isn't enough, add more debug output for yourself
 399               into the functions you find relevant. See The section on Debug
 400               Logging in this guide for more information. You might
 401               also try to run the program in <command>gdb</command>
 402               instead of using the WINE-debugger. If you do that, use
 403               <parameter>handle SIGSEGV nostop noprint</parameter> to
 404               disable the handling of seg faults inside
 405               <command>gdb</command> (needed for Win16).
 406             </para>
 407           </listitem>
 408           <listitem>
 409             <para>
 410               You can also set a breakpoint for that function. Start wine
 411               useing <command>winedbg</command> instead of
 412               <command>wine</command>. Once the debugger is is running enter
 413               <command>break</command> <parameter>KERNEL_LSTRLEN</parameter>
 414               (replace by function you want to debug, CASE IS RELEVANT)
 415               to set a breakpoint.  Then
 416               use <command>continue</command> to start normal
 417               program-execution. Wine will stop if it reaches the
 418               breakpoint. If the program isn't yet at the crashing call
 419               of that function, use <command>continue</command> again
 420               until you are about to enter that function. You may now
 421               proceed with single-stepping the function until you reach
 422               the point of crash. Use the other debugger commands to
 423               print registers and the like.
 424             </para>
 425           </listitem>
 426         </orderedlist>
 427       </sect2>
 428
 429       <sect2>
 430         <title>Program hangs, nothing happens</title>
 431
 432         <para>
 433           Start the program with <command>winedbg</command> instead of
 434           <command>wine</command>. When the program locks up switch to the
 435           winedbg terminal and press
 436           <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo>. this
 437           will stop the program and let you debug the program as you would for
 438           a crash.
 439         </para>
 440       </sect2>
 441
 442       <sect2>
 443         <title>Program reports an error with a Messagebox</title>
 444
 445         <para>
 446           Sometimes programs are reporting failure using more or
 447           less nondescript messageboxes. We can debug this using the
 448           same method as Crashes, but there is one problem... For
 449           setting up a message box the program also calls Wine
 450           producing huge chunks of debug code.
 451         </para>
 452         <para>
 453           Since the failure happens usually directly before setting up
 454           the Messagebox you can start winedbg and set a
 455           breakpoint at <function>MessageBoxA</function> (called by win16
 456           and win32 programs) and proceed with
 457           <command>continue</command>. With <parameter>--debugmsg
 458             +all</parameter> Wine will now stop directly before setting
 459           up the Messagebox. Proceed as explained above.
 460         </para>
 461         <para>
 462           You can also run wine using <command>wine -debugmsg +relay
 463             program.exe 2>&1 | less -i</command> and in
 464           <command>less</command> search for <quote>MessageBox</quote>.
 465         </para>
 466       </sect2>
 467
 468       <sect2>
 469         <title>Disassembling programs:</title>
 470
 471         <para>
 472           You may also try to disassemble the offending program to
 473           check for undocumented features and/or use of them.
 474         </para>
 475         <para>
 476           The best, freely available, disassembler for Win16 programs is
 477           <application>Windows Codeback</application>, archivename
 478           <filename>wcbxxx.zip</filename>, which usually can be found in
 479           the <filename>Cica-Mirror</filename> subdirectory on the WINE
 480           ftpsites. (See <filename>ANNOUNCE</filename>).
 481         </para>
 482         <para>
 483           Disassembling win32 programs is possible using
 484           <application>Windows Disassembler 32</application>, archivename
 485           something like <filename>w32dsm87.zip</filename> (or similar)
 486           on <systemitem class="systemname">ftp.winsite.com</systemitem>
 487           and mirrors.  The shareware version does not allow saving of
 488           disassembly listings. You can also use the newer (and in the
 489           full version better) <application>Interactive
 490             Disassembler</application> (IDA) from the ftp sites mentioned
 491           at the end of the document. Understanding disassembled code is
 492           mostly a question of exercise.
 493         </para>
 494         <para>
 495           Most code out there uses standard C function entries (for it
 496           is usually  written in C). Win16 function entries usually
 497           look like that:
 498         </para>
 499         <programlisting>
 500 push bp
 501 mov bp, sp
 502 ... function code ..
 503 retf XXXX       &lt;--------- XXXX is number of bytes of arguments
 504         </programlisting>
 505         <para>
 506           This is a <function>FAR</function> function with no local
 507           storage. The arguments usually start at
 508           <literal>[bp+6]</literal> with increasing offsets. Note, that
 509           <literal>[bp+6]</literal> belongs to the
 510           <emphasis>rightmost</emphasis> argument, for exported win16
 511           functions use the PASCAL calling convention. So, if we use
 512           <function>strcmp(a,b)</function> with <parameter>a</parameter>
 513           and <parameter>b</parameter> both 32 bit variables
 514           <parameter>b</parameter> would be at <literal>[bp+6]</literal>
 515           and <parameter>a</parameter> at <literal>[bp+10]</literal>.
 516         </para>
 517         <para>
 518           Most functions make also use of local storage in the stackframe:
 519         </para>
 520         <programlisting>
 521 enter 0086, 00
 522 ... function code ...
 523 leave
 524 retf XXXX
 525         </programlisting>
 526         <para>
 527           This does mostly the same as above, but also adds
 528           <literal>0x86</literal> bytes of stackstorage, which is
 529           accessed using <literal>[bp-xx]</literal>. Before calling a
 530           function, arguments are pushed on the stack using something
 531           like this:
 532         </para>
 533         <programlisting>
 534 push word ptr [bp-02]   &lt;- will be at [bp+8]
 535 push di                 &lt;- will be at [bp+6]
 536 call KERNEL.LSTRLEN
 537         </programlisting>
 538         <para>
 539           Here first the selector and then the offset to the passed
 540           string are pushed.
 541         </para>
 542       </sect2>
 543
 544       <sect2>
 545         <title>Sample debugging session:</title>
 546
 547         <para>
 548           Let's debug the infamous Word <filename>SHARE.EXE</filename>
 549           messagebox:
 550         </para>
 551         <screen>
 552 |marcus@jet $ wine winword.exe
 553 |            +---------------------------------------------+
 554 |            | !  You must leave Windows and load SHARE.EXE|
 555 |            |    before starting Word.                    |
 556 |            +---------------------------------------------+
 557         </screen>
 558         <screen>
 559 |marcus@jet $ wine winword.exe -debugmsg +relay -debug
 560 |CallTo32(wndproc=0x40065bc0,hwnd=000001ac,msg=00000081,wp=00000000,lp=00000000)
 561 |Win16 task 'winword': Breakpoint 1 at 0x01d7:0x001a
 562 |CallTo16(func=0127:0070,ds=0927)
 563 |Call WPROCS.24: TASK_RESCHEDULE() ret=00b7:1456 ds=0927
 564 |Ret  WPROCS.24: TASK_RESCHEDULE() retval=0x8672 ret=00b7:1456 ds=0927
 565 |CallTo16(func=01d7:001a,ds=0927)
 566 |     AX=0000 BX=3cb4 CX=1f40 DX=0000 SI=0000 DI=0927 BP=0000 ES=11f7
 567 |Loading symbols: /home/marcus/wine/wine...
 568 |Stopped on breakpoint 1 at 0x01d7:0x001a
 569 |In 16 bit mode.
 570 |Wine-dbg>break MessageBoxA                          &lt;---- Set Breakpoint
 571 |Breakpoint 2 at 0x40189100 (MessageBoxA [msgbox.c:190])
 572 |Wine-dbg>c                                            &lt;---- Continue
 573 |Call KERNEL.91: INITTASK() ret=0157:0022 ds=08a7
 574 |     AX=0000 BX=3cb4 CX=1f40 DX=0000 SI=0000 DI=08a7 ES=11d7 EFL=00000286
 575 |CallTo16(func=090f:085c,ds=0dcf,0x0000,0x0000,0x0000,0x0000,0x0800,0x0000,0x0000,0x0dcf)
 576 |...                                                   &lt;----- Much debugoutput
 577 |Call KERNEL.136: GETDRIVETYPE(0x0000) ret=060f:097b ds=0927
 578                                ^^^^^^ Drive 0 (A:)
 579 |Ret  KERNEL.136: GETDRIVETYPE() retval=0x0002 ret=060f:097b ds=0927
 580                                         ^^^^^^  DRIVE_REMOVEABLE
 581                                                 (It is a floppy diskdrive.)
 582
 583 |Call KERNEL.136: GETDRIVETYPE(0x0001) ret=060f:097b ds=0927
 584                                ^^^^^^ Drive 1 (B:)
 585 |Ret  KERNEL.136: GETDRIVETYPE() retval=0x0000 ret=060f:097b ds=0927
 586                                         ^^^^^^  DRIVE_CANNOTDETERMINE
 587                                                 (I don't have drive B: assigned)
 588
 589 |Call KERNEL.136: GETDRIVETYPE(0x0002) ret=060f:097b ds=0927
 590                                ^^^^^^^ Drive 2 (C:)
 591 |Ret  KERNEL.136: GETDRIVETYPE() retval=0x0003 ret=060f:097b ds=0927
 592                                         ^^^^^^ DRIVE_FIXED
 593                                                (specified as a harddisk)
 594
 595 |Call KERNEL.97: GETTEMPFILENAME(0x00c3,0x09278364"doc",0x0000,0927:8248) ret=060f:09b1 ds=0927
 596                                  ^^^^^^           ^^^^^        ^^^^^^^^^
 597                                  |                |            |buffer for fname
 598                                  |                |temporary name ~docXXXX.tmp
 599                                  |Force use of Drive C:.
 600
 601 |Warning: GetTempFileName returns 'C:~doc9281.tmp', which doesn't seem to be writeable.
 602 |Please check your configuration file if this generates a failure.
 603         </screen>
 604         <para>
 605           Whoops, it even detects that something is wrong!
 606         </para>
 607         <screen>
 608 |Ret  KERNEL.97: GETTEMPFILENAME() retval=0x9281 ret=060f:09b1 ds=0927
 609                                           ^^^^^^ Temporary storage ID
 610
 611 |Call KERNEL.74: OPENFILE(0x09278248"C:~doc9281.tmp",0927:82da,0x1012) ret=060f:09d8 ds=0927
 612                                     ^^^^^^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^
 613                                     |filename        |OFSTRUCT |open mode:
 614
 615                                        OF_CREATE|OF_SHARE_EXCLUSIVE|OF_READWRITE
 616         </screen>
 617         <para>
 618           This fails, since my <medialabel>C:</medialabel> drive is in
 619           this case mounted readonly.
 620         </para>
 621         <screen>
 622 |Ret  KERNEL.74: OPENFILE() retval=0xffff ret=060f:09d8 ds=0927
 623                                    ^^^^^^ HFILE_ERROR16, yes, it failed.
 624
 625 |Call USER.1: MESSAGEBOX(0x0000,0x09278376"Sie mussen Windows verlassen und SHARE.EXE laden bevor Sie Word starten.",0x00000000,0x1030) ret=060f:084f ds=0927
 626         </screen>
 627         <para>
 628           And MessageBox'ed.
 629         </para>
 630         <screen>
 631 |Stopped on breakpoint 2 at 0x40189100 (MessageBoxA [msgbox.c:190])
 632 |190     {              &lt;- the sourceline
 633 In 32 bit mode.
 634 Wine-dbg>
 635         </screen>
 636         <para>
 637           The code seems to find a writeable harddisk and tries to create
 638           a file there. To work around this bug, you can define
 639           <medialabel>C:</medialabel> as a networkdrive, which is ignored
 640           by the code above.
 641         </para>
 642       </sect2>
 643
 644       <sect2>
 645         <title>Debugging Tips</title>
 646
 647         <para>
 648           Here are some useful debugging tips, added by Andreas Mohr:
 649         </para>
 650
 651         <itemizedlist>
 652           <listitem>
 653             <para>
 654               If you have a program crashing at such an early loader phase that you can't
 655               use the Wine debugger normally, but Wine already executes the program's
 656               start code, then you may use a special trick. You should do a
 657               <programlisting>
 658 wine --debugmsg +relay program
 659               </programlisting>
 660               to get a listing of the functions the program calls in its start function.
 661               Now you do a
 662               <programlisting>
 663 winedbg winfile.exe
 664               </programlisting>
 665             </para>
 666             <para>
 667               This way, you get into <command>winedbg</command>. Now you
 668               can set a breakpoint on any function the program calls in
 669               the start function and just type <userinput>c</userinput>
 670               to bypass the eventual calls of Winfile to this function
 671               until you are finally at the place where this function gets
 672               called by the crashing start function. Now you can proceed
 673               with your debugging as usual.
 674             </para>
 675           </listitem>
 676           <listitem>
 677             <para>
 678               If you try to run a program and it quits after showing an error messagebox,
 679               the problem can usually be identified in the return value of one of the
 680               functions executed before <function>MessageBox()</function>.
 681               That's why you should re-run the program with e.g.
 682               <programlisting>
 683 wine --debugmsg +relay &lt;program name> &>relmsg
 684               </programlisting>
 685               Then do a <command>more relmsg</command> and search for the
 686               last occurrence of a call to the string "MESSAGEBOX". This is a line like
 687               <programlisting>
 688 Call USER.1: MESSAGEBOX(0x0000,0x01ff1246 "Runtime error 219 at 0004:1056.",0x00000000,0x1010) ret=01f7:2160 ds=01ff
 689               </programlisting>
 690               In my example the lines before the call to
 691               <function>MessageBox()</function> look like that:
 692               <programlisting>
 693 Call KERNEL.96: FREELIBRARY(0x0347) ret=01cf:1033 ds=01ff
 694 CallTo16(func=033f:0072,ds=01ff,0x0000)
 695 Ret  KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:1033 ds=01ff
 696 Call KERNEL.96: FREELIBRARY(0x036f) ret=01cf:1043 ds=01ff
 697 CallTo16(func=0367:0072,ds=01ff,0x0000)
 698 Ret  KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:1043 ds=01ff
 699 Call KERNEL.96: FREELIBRARY(0x031f) ret=01cf:105c ds=01ff
 700 CallTo16(func=0317:0072,ds=01ff,0x0000)
 701 Ret  KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:105c ds=01ff
 702 Call USER.171: WINHELP(0x02ac,0x01ff05b4 "COMET.HLP",0x0002,0x00000000) ret=01cf:1070 ds=01ff
 703 CallTo16(func=0117:0080,ds=01ff)
 704 Call WPROCS.24: TASK_RESCHEDULE() ret=00a7:0a2d ds=002b
 705 Ret  WPROCS.24: TASK_RESCHEDULE() retval=0x0000 ret=00a7:0a2d ds=002b
 706 Ret  USER.171: WINHELP() retval=0x0001 ret=01cf:1070 ds=01ff
 707 Call KERNEL.96: FREELIBRARY(0x01be) ret=01df:3e29 ds=01ff
 708 Ret  KERNEL.96: FREELIBRARY() retval=0x0000 ret=01df:3e29 ds=01ff
 709 Call KERNEL.52: FREEPROCINSTANCE(0x02cf00ba) ret=01f7:1460 ds=01ff
 710 Ret  KERNEL.52: FREEPROCINSTANCE() retval=0x0001 ret=01f7:1460 ds=01ff
 711 Call USER.1: MESSAGEBOX(0x0000,0x01ff1246 "Runtime error 219 at 0004:1056.",0x00000000,0x1010) ret=01f7:2160 ds=01ff
 712               </programlisting>
 713             </para>
 714             <para>
 715               I think that the call to <function>MessageBox()</function>
 716               in this example is <emphasis>not</emphasis> caused by a
 717               wrong result value of some previously executed function
 718               (it's happening quite often like that), but instead the
 719               messagebox complains about a runtime error at
 720               <literal>0x0004:0x1056</literal>.
 721             </para>
 722             <para>
 723               As the segment value of the address is only
 724               <literal>4</literal>, I think that that is only an internal
 725               program value. But the offset address reveals something
 726               quite interesting: Offset <literal>1056</literal> is
 727               <emphasis>very</emphasis> close to the return address of
 728               <function>FREELIBRARY()</function>:
 729               <programlisting>
 730 Call KERNEL.96: FREELIBRARY(0x031f) ret=01cf:105c ds=01ff
 731                                              ^^^^
 732               </programlisting>
 733             </para>
 734             <para>
 735               Provided that segment <literal>0x0004</literal> is indeed segment
 736               <literal>0x1cf</literal>, we now we can use IDA                 (available at
 737               <ulink url="ftp://ftp.uni-koeln.de/pc/msdos/programming/assembler/ida35bx.zip">
 738                 ftp://ftp.uni-koeln.de/pc/msdos/programming/assembler/ida35bx.zip</ulink>) to
 739               disassemble the part that caused the error. We just have to find the address of
 740               the call to <function>FreeLibrary()</function>. Some lines before that the
 741               runtime error occurred. But be careful! In some cases you don't have to
 742               disassemble the main program, but instead some DLL called by it in order to find
 743               the correct place where the runtime error occurred. That can be determined by
 744               finding the origin of the segment value (in this case <literal>0x1cf</literal>).
 745             </para>
 746           </listitem>
 747           <listitem>
 748             <para>
 749               If you have created a relay file of some crashing
 750               program and want to set a breakpoint at a certain
 751               location which is not yet available as the program loads
 752               the breakpoint's segment during execution, you may set a
 753               breakpoint to <function>GetVersion16/32</function> as
 754               those functions are called very often.
 755             </para>
 756             <para>
 757               Then do a <userinput>c</userinput> until you are able to
 758               set this breakpoint without error message.
 759             </para>
 760           </listitem>
 761           <listitem>
 762             <para>
 763               Some useful programs:
 764             </para>
 765             <variablelist>
 766               <varlistentry>
 767                 <term>
 768                   <application>IDA</application>:
 769                   <filename>
 770                     <ulink url="ftp://ftp.uni-koeln.de/pc/msdos/programming/assembler/ida35bx.zip">
 771                       ftp://ftp.uni-koeln.de/pc/msdos/programming/assembler/ida35bx.zip</ulink>
 772                   </filename>
 773                 </term>
 774                 <listitem>
 775                   <para>
 776                     <emphasis>Very</emphasis> good DOS disassembler ! It's badly needed
 777                     for debugging Wine sometimes.
 778                   </para>
 779                 </listitem>
 780               </varlistentry>
 781               <varlistentry>
 782                 <term>
 783                   <application>XRAY</application>:
 784                   <filename>
 785                     <ulink url="ftp://ftp.th-darmstadt.de/pub/machines/ms-dos/SimTel/msdos/asmutil/xray15.zip">
 786                       ftp://ftp.th-darmstadt.de/pub/machines/ms-dos/SimTel/msdos/asmutil/xray15.zip</ulink>
 787                   </filename>
 788                 </term>
 789                 <listitem>
 790                   <para>
 791                     Traces DOS calls (Int 21h, DPMI, ...). Use it with
 792                     Windows to correct file management problems etc.
 793                   </para>
 794                 </listitem>
 795               </varlistentry>
 796               <varlistentry>
 797                 <term>
 798                   <application>pedump</application>:
 799                   <filename>
 800                     <ulink url="http://oak.oakland.edu/pub/simtelnet/win95/prog/pedump.zip">
 801                       http://oak.oakland.edu/pub/simtelnet/win95/prog/pedump.zip</ulink>
 802                   </filename>
 803                 </term>
 804                 <listitem>
 805                   <para>
 806                     Dumps the imports and exports of a PE (Portable
 807                     Executable) DLL.
 808                   </para>
 809                 </listitem>
 810               </varlistentry>
 811               <varlistentry>
 812                 <term>
 813                   <application>winedump</application>:
 814                 </term>
 815                 <listitem>
 816                   <para>
 817                     Dumps the imports and exports of a PE (Portable
 818                     Executable) DLL (included in wine tree).
 819                   </para>
 820                 </listitem>
 821               </varlistentry>
 822             </variablelist>
 823           </listitem>
 824         </itemizedlist>
 825       </sect2>
 826
 827       <sect2>
 828         <title>Some basic debugger usages:</title>
 829
 830         <para>
 831           After starting your program with
 832         </para>
 833         <screen>
 834 wine -debug myprog.exe
 835         </screen>
 836         <para>
 837           the program loads and you get a prompt at the program
 838           starting point. Then you can set breakpoints:
 839         </para>
 840         <screen>
 841   b RoutineName      (by outine name) OR
 842   b *0x812575        (by address)
 843         </screen>
 844         <para>
 845           Then you hit <command>c</command> (continue) to run the
 846           program. It stops at the breakpoint. You can type
 847         </para>
 848         <screen>
 849   step               (to step one line) OR
 850   stepi              (to step one machine instruction at a time;
 851                       here, it helps to know the basic 386
 852                       instruction set)
 853   info reg           (to see registers)
 854   info stack         (to see hex values in the stack)
 855   info local         (to see local variables)
 856   list &lt;line number&gt; (to list source code)
 857   x &lt;variable name&gt;  (to examine a variable; only works if code
 858                       is not compiled with optimization)
 859   x 0x4269978        (to examine a memory location)
 860   ?                  (help)
 861   q                  (quit)
 862         </screen>
 863         <para>
 864           By hitting <keycap>Enter</keycap>, you repeat the last
 865           command.
 866         </para>
 867       </sect2>
 868     </sect1>
 869
 870
 871     <sect1 id="memory-addresses">
 872       <title>Useful memory addresses</title>
 873       <para>
 874         Written by &name-andreas-mohr; <email>&email-andreas-mohr;</email>
 875       </para>
 876       <para>
 877         Wine uses several different kinds of memory addresses.
 878       </para>
 879       <variablelist>
 880         <varlistentry>
 881           <term>
 882             Win32/"normal" Wine addresses/Linux: linear addresses.
 883           </term>
 884           <listitem>
 885             <para>
 886               Linear addresses can be everything from 0x0 up to
 887               0xffffffff.  In Wine on Linux they are often around
 888               e.g. 0x08000000, 0x00400000 (std. Win32 program load
 889               address), 0x40000000.  Every Win32 process has its own
 890               private 4GB address space (that is, from 0x0 up to
 891               0xffffffff).
 892             </para>
 893           </listitem>
 894         </varlistentry>
 895         <varlistentry>
 896           <term>
 897             Win16 "enhanced mode": segmented addresses.
 898           </term>
 899           <listitem>
 900             <para>
 901               These are the "normal" Win16 addresses, called SEGPTR.
 902               They have a segment:offset notation, e.g. 0x01d7:0x0012.
 903               The segment part usually is a "selector", which *always*
 904               has the lowest 3 bits set.  Some sample selectors are
 905               0x1f7, 0x16f, 0x8f.  If these bits are set except for
 906               the lowest bit, as e.g. with 0x1f6,xi then it might be a
 907               handle to global memory. Just set the lowest bit to get
 908               the selector in these cases.  A selector kind of
 909               "points" to a certain linear (see above) base address.
 910               It has more or less three important attributes: segment
 911               base address, segment limit, segment access rights.
 912             </para>
 913             <para>
 914               Example:
 915             </para>
 916             <para>
 917               Selector 0x1f7 (0x40320000, 0x0000ffff, r-x) So 0x1f7
 918               has a base address of 0x40320000, the segment's last
 919               address is 0x4032ffff (limit 0xffff), and it's readable
 920               and executable.  So an address of 0x1f7:0x2300 would be
 921               the linear address of 0x40322300.
 922             </para>
 923           </listitem>
 924         </varlistentry>
 925         <varlistentry>
 926           <term>
 927             DOS/Win16 "standard mode"
 928           </term>
 929           <listitem>
 930             <para>
 931               They, too, have a segment:offset notation.  But they are
 932               completely different from "normal" Win16 addresses, as
 933               they just represent at most 1MB of memory: The segment
 934               part can be anything from 0 to 0xffff, and it's the same
 935               with the offset part.
 936             </para>
 937             <para>
 938               Now the strange thing is the calculation that's behind
 939               these addresses: Just calculate segment*16 + offset in
 940               order to get a "linear DOS" address.  So
 941               e.g. 0x0f04:0x3628 results in 0xf040 + 0x3628 = 0x12668.
 942               And the highest address you can get is 0xfffff (1MB), of
 943               course.  In Wine, this "linear DOS" address of 0x12668
 944               has to be added to the linear base address of the
 945               corresponding DOS memory allocated for dosmod in order
 946               to get the true linear address of a DOS seg:offs
 947               address.  And make sure that you're doing this in the
 948               correct process with the correct linear address space,
 949               of course ;-)
 950             </para>
 951           </listitem>
 952         </varlistentry>
 953       </variablelist>
 954     </sect1>
 955
 956     <sect1 id="dbg-config">
 957       <title>Configuration</title>
 958
 959       <sect2>
 960         <title>Registry configuration</title>
 961
 962         <para>
 963           The Windows' debugging API uses a registry entry to know
 964           which debugger to invoke when an unhandled exception occurs
 965           (see <link endterm="dbg-exception-title"
 966           linkend="dbg-on-exception"></link> for some details). Two
 967           values in key
 968         </para>
 969         <programlisting>
 970 "MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\AeDebug"
 971         </programlisting>
 972         <para>
 973           Determine the behavior:
 974         </para>
 975         <variablelist>
 976           <varlistentry>
 977             <term>Debugger:</term>
 978             <listitem>
 979               <para>
 980                 this is the command line used to launch the debugger
 981                 (it uses two <function>printf</function> formats
 982                 (<literal>%ld</literal>) to pass context dependent
 983                 information to  the debugger). You should put here a
 984                 complete path to your debugger
 985                 (<command>WineDbg</command> can of course be used, but
 986                 any other Windows' debugging API aware debugger will
 987                 do).
 988                 The path to the debugger you chose to use must be reachable
 989                 via a DOS drive in the Wine config file !
 990               </para>
 991             </listitem>
 992           </varlistentry>
 993           <varlistentry>
 994             <term>Auto:</term>
 995             <listitem>
 996               <para>
 997                 if this value is zero, a message box will ask the
 998                 user if he/she wishes to launch the debugger when an
 999                 unhandled exception occurs. Otherwise, the debugger
1000                 is automatically started.
1001               </para>
1002             </listitem>
1003           </varlistentry>
1004         </variablelist>
1005
1006         <para>
1007           A regular Wine registry looks like:
1008         </para>
1009         <programlisting>
1010 [MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\AeDebug] 957636538
1011 "Auto"=dword:00000001
1012 "Debugger"="winedbg --debugmsg -all %ld %ld"
1013         </programlisting>
1014
1015         <note>
1016           <title>Note 1</title>
1017           <para>
1018             creating this key is mandatory. Not doing so will not
1019             fire the debugger when an exception occurs.
1020           </para>
1021         </note>
1022         <note>
1023           <title>Note 2</title>
1024           <para>
1025             <command>wineinstall</command> (available in Wine source)
1026             sets up this correctly.
1027             However, due to some limitation of the registry installed,
1028             if a previous Wine installation exists, it's safer to
1029             remove the whole
1030           </para>
1031           <programlisting>
1032 [MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\AeDebug]
1033           </programlisting>
1034           <para>
1035             key before running again <command>wineinstall</command> to
1036             regenerate this key.
1037           </para>
1038         </note>
1039       </sect2>
1040
1041       <sect2>
1042         <title>WineDbg configuration</title>
1043
1044         <para>
1045           <command>WineDbg</command> can be configured through a number
1046           of options. Those options are stored in the registry, on a
1047           per user basis. The key is (in <emphasis>my</emphasis> registry)
1048         </para>
1049         <programlisting>
1050 [eric\\Software\\Wine\\WineDbg]
1051         </programlisting>
1052         <para>
1053           Those options can be read/written while inside
1054           <command>WineDbg</command>, as part of the debugger
1055           expressions. To refer to one of these options, its name must
1056           be  prefixed by a <literal>$</literal> sign. For example,
1057         </para>
1058         <programlisting>
1059 set $BreakAllThreadsStartup = 1
1060         </programlisting>
1061         <para>
1062           sets the option <varname>BreakAllThreadsStartup</varname> to
1063           <literal>TRUE</literal>.
1064         </para>
1065         <para>
1066           All the options are read from the registry when
1067           <command>WineDbg</command> starts (if no corresponding value
1068           is found, a default value is used), and are written back to
1069           the registry when <command>WineDbg</command> exits (hence,
1070           all modifications to those options are automatically saved
1071           when <command>WineDbg</command> terminates).
1072         </para>
1073         <para>
1074           Here's the list of all options:
1075         </para>
1076
1077         <sect3>
1078           <title>Controlling when the debugger is entered</title>
1079
1080           <variablelist>
1081             <varlistentry>
1082               <term><varname>BreakAllThreadsStartup</varname></term>
1083               <listitem>
1084                 <para>
1085                   Set to <literal>TRUE</literal> if at all threads
1086                   start-up the debugger stops  set to
1087                   <literal>FALSE</literal> if only at the first thread
1088                   startup of a given process the debugger stops.
1089                   <literal>FALSE</literal> by default.
1090                 </para>
1091               </listitem>
1092             </varlistentry>
1093             <varlistentry>
1094               <term><varname>BreakOnCritSectTimeOut</varname></term>
1095               <listitem>
1096                 <para>
1097                   Set to <literal>TRUE</literal> if the debugger stops
1098                   when a critical section times out (5 minutes);
1099                   <literal>TRUE</literal> by default.
1100                 </para>
1101               </listitem>
1102             </varlistentry>
1103             <varlistentry>
1104               <term><varname>BreakOnAttach</varname></term>
1105               <listitem>
1106                 <para>
1107                   Set to <literal>TRUE</literal> if when
1108                   <command>WineDbg</command> attaches to an existing
1109                   process after an unhandled exception,
1110                   <command>WineDbg</command> shall be entered on the
1111                   first attach event. Since the attach event is
1112                   meaningless in the context of an exception event
1113                   (the next event  which is the exception event is of
1114                   course relevant), that option is likely to be
1115                   <literal>FALSE</literal>.
1116                 </para>
1117               </listitem>
1118             </varlistentry>
1119             <varlistentry>
1120               <term><varname>BreakOnFirstChance</varname></term>
1121               <listitem>
1122                 <para>
1123                   An exception can generate two debug events. The
1124                   first one is passed to the debugger (known as a
1125                   first chance) just after the exception. The debugger
1126                   can then decides either to resume execution (see
1127                   <command>WineDbg</command>'s <command>cont</command>
1128                   command) or pass the exception up to the exception
1129                   handler chain in the program (if it exists)
1130                   (<command>WineDbg</command> implements this through the
1131                   <command>pass</command> command). If none of the
1132                   exception handlers takes care of the exception, the
1133                   exception event is sent again to the debugger (known
1134                   as last chance exception). You cannot pass on a last
1135                   exception. When the
1136                   <varname>BreakOnFirstChance</varname> exception is
1137                   <literal>TRUE</literal>, then winedbg is entered for
1138                   both first and last chance execptions (to
1139                   <literal>FALSE</literal>, it's only entered for last
1140                   chance exceptions).
1141                 </para>
1142               </listitem>
1143             </varlistentry>
1144             <varlistentry>
1145               <term><varname>BreakOnDllLoad</varname></term>
1146               <listitem>
1147                 <para>
1148                   Set to <literal>TRUE</literal> if the debugger stops
1149                   when a DLL is loaded into memory; when the debugger
1150                   is invoked after a crash, the DLLs already mapped in
1151                   memory will not trigger this break.
1152                   <literal>FALSE</literal> by default.
1153                 </para>
1154               </listitem>
1155             </varlistentry>
1156           </variablelist>
1157         </sect3>
1158
1159         <sect3>
1160           <title>Output handling</title>
1161
1162           <variablelist>
1163             <varlistentry>
1164               <term><varname>ConChannelMask</varname></term>
1165               <listitem>
1166                 <para>
1167                   Mask of active debugger output channels on console
1168                 </para>
1169               </listitem>
1170             </varlistentry>
1171             <varlistentry>
1172               <term><varname>StdChannelMask</varname></term>
1173               <listitem>
1174                 <para>
1175                   Mask of active debugger output channels on <filename>stderr</filename>
1176                 </para>
1177               </listitem>
1178             </varlistentry>
1179             <varlistentry>
1180               <term><varname>UseXTerm</varname></term>
1181               <listitem>
1182                 <para>
1183                   Set to <literal>TRUE</literal> if the debugger uses
1184                   its own <command>xterm</command> window for console
1185                   input/output.  Set to <literal>FALSE</literal> if
1186                   the debugger uses the current Unix console for
1187                   input/output
1188                 </para>
1189               </listitem>
1190             </varlistentry>
1191           </variablelist>
1192
1193           <para>
1194             Those last 3 variables are jointly used in two generic ways:
1195           </para>
1196
1197           <orderedlist>
1198             <listitem>
1199               <para>default</para>
1200               <programlisting>
1201 ConChannelMask = DBG_CHN_MESG (1)
1202 StdChannelMask = 0
1203 UseXTerm = 1
1204               </programlisting>
1205               <para>
1206                 In this case, all input/output goes into a specific
1207                 <command>xterm</command> window (but all debug
1208                 messages <function>TRACE</function>,
1209                 <function>WARN</function>... still goes to tty where
1210                 wine is run from).
1211               </para>
1212             </listitem>
1213             <listitem>
1214               <para>
1215                 to have all input/output go into the tty where Wine
1216                 was started from (to be used in a X11-free
1217                 environment)
1218               </para>
1219               <screen>
1220 ConChannelMask = 0
1221 StdChannelMask = DBG_CHN_MESG (1)
1222 UseXTerm = 1
1223               </screen>
1224             </listitem>
1225           </orderedlist>
1226           <para>
1227             Those variables also allow, for example for debugging
1228             purposes, to use:
1229           </para>
1230           <screen>
1231 ConChannelMask = 0xfff
1232 StdChannelMask = 0xfff
1233 UseXTerm = 1
1234           </screen>
1235           <para>
1236             This allows to redirect all <function>WineDbg</function>
1237             output to both tty Wine was started from, and
1238             <command>xterm</command> debugging window. If Wine (or
1239             <command>WineDbg</command>) was started with a redirection
1240             of <filename>stdout</filename> and/or
1241             <filename>stderr</filename> to a file (with for
1242             example &gt;& shell redirect command), you'll get in that
1243             file both outputs. It may be interesting to look in the
1244             relay trace for specific values which the process segv'ed
1245             on.
1246           </para>
1247         </sect3>
1248
1249         <sect3>
1250           <title>Context information</title>
1251
1252           <variablelist>
1253             <varlistentry>
1254               <term><varname>ThreadId</varname></term>
1255               <listitem>
1256                 <para>ID of the <varname>W-thread</varname> currently
1257                   examined by the debugger</para>
1258               </listitem>
1259             </varlistentry>
1260             <varlistentry>
1261               <term><varname>ProcessId</varname></term>
1262               <listitem>
1263                 <para>ID of the <varname>W-thread</varname> currently
1264                   examined by the debugger</para>
1265               </listitem>
1266             </varlistentry>
1267             <varlistentry>
1268               <term>&lt;registers></term>
1269               <listitem>
1270                 <para>All CPU registers are also available</para>
1271               </listitem>
1272             </varlistentry>
1273           </variablelist>
1274
1275           <para>
1276             The <varname>ThreadId</varname> and
1277             <varname>ProcessId</varname> variables can be handy to set
1278             conditional breakpoints on a given thread or process.
1279           </para>
1280         </sect3>
1281       </sect2>
1282     </sect1>
1283
1284
1285     <sect1 id="dbg-commands">
1286       <title>WineDbg Command Reference</title>
1287
1288       <sect2>
1289         <title>Misc</title>
1290
1291         <screen>
1292 abort           aborts the debugger
1293 quit            exits the debugger
1294
1295 attach N        attach to a W-process (N is its ID). IDs can be
1296                 obtained using the walk process command
1297 detach          detach from a W-process. WineDbg will exit (this may
1298                 be changed later on)
1299         </screen>
1300         <screen>
1301 help            prints some help on the commands
1302 help info       prints some help on info commands
1303         </screen>
1304         <screen>
1305 mode 16         switch to 16 bit mode
1306 mode 32         switch to 32 bit mode
1307         </screen>
1308       </sect2>
1309
1310       <sect2>
1311         <title>Flow control</title>
1312
1313         <screen>
1314 cont            continue execution until next breakpoint or exception.
1315 pass            pass the exception event up to the filter chain.
1316 step            continue execution until next C line of code (enters
1317                 function call)
1318 next            continue execution until next C line of code (doesn't
1319                 enter function call)
1320 stepi           execute next assembly instruction (enters function
1321                 call)
1322 nexti           execute next assembly instruction (doesn't enter
1323                 function call)
1324 finish          do nexti commands until current function is exited
1325         </screen>
1326         <para>
1327           cont, step, next, stepi, nexti can be postfixed by a
1328           number (N), meaning that the command must be executed N
1329           times.
1330         </para>
1331       </sect2>
1332
1333       <sect2>
1334         <title>Breakpoints, watch points</title>
1335
1336         <screen>
1337 enable N        enables (break|watch)point #N
1338 disable N       disables (break|watch)point #N
1339 delete N        deletes  (break|watch)point #N
1340 cond N          removes any a existing condition to (break|watch)point N
1341 cond N &lt;expr&gt;     adds condition &lt;expr&gt; to (break|watch)point N. &lt;expr&gt;
1342                 will be evaluated each time the breakpoint is hit. If
1343                 the result is a zero value, the breakpoint isn't
1344                 triggered
1345 break * N       adds a breakpoint at address N
1346 break &lt;id&gt;        adds a breakpoint at the address of symbol &lt;id&gt;
1347 break &lt;id&gt; N      adds a breakpoint at the address of symbol &lt;id&gt; (N ?)
1348 break N         adds a breakpoint at line N of current source file
1349 break           adds a breakpoint at current $pc address
1350 watch * N       adds a watch command (on write) at address N (on 4 bytes)
1351 watch &lt;id&gt;        adds a watch command (on write) at the address of
1352                 symbol &lt;id&gt;
1353 info break      lists all (break|watch)points (with state)
1354         </screen>
1355         <para>
1356           When setting a breakpoint on an &lt;id&gt;, if several symbols with this
1357           &lt;id&gt; exist, the debugger will prompt for the symbol you want to use.
1358           Pick up the one you want from its number.
1359         </para>
1360         <para>
1361           Alternatively you can specify a DLL in the &lt;id&gt; (for example
1362           MYDLL.DLL.myFunc for function myFunc of
1363           <filename>G:\AnyPath\MyDll.dll)</filename>.
1364         </para>
1365         <para>
1366           You can use the symbol <emphasis>EntryPoint</emphasis> to stand for
1367           the entry point of the Dll.
1368         </para>
1369         <para>
1370           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
1371           recall the name of the symbol and will try to set the breakpoint each time a new module is loaded (until it succeeds).
1372         </para>
1373       </sect2>
1374
1375       <sect2>
1376         <title>Stack manipulation</title>
1377
1378         <screen>
1379 bt              print calling stack of current thread
1380 bt N            print calling stack of thread of ID N (note: this
1381                 doesn't change the position of the current frame as
1382                 manipulated by the up & dn commands)
1383 up              goes up one frame in current thread's stack
1384 up N            goes up N frames in current thread's stack
1385 dn              goes down one frame in current thread's stack
1386 dn N            goes down N frames in current thread's stack
1387 frame N         set N as the current frame for current thread's stack
1388 info local      prints information on local variables for current
1389                 function
1390         </screen>
1391       </sect2>
1392
1393       <sect2>
1394         <title>Directory & source file manipulation</title>
1395
1396         <screen>
1397 show dir
1398 dir &lt;pathname&gt;
1399 dir
1400 symbolfile &lt;pathname&gt;   loads external symbol definition
1401 symbolfile &lt;pathname&gt; N loads external symbol definition
1402                            (applying an offset of N to addresses)
1403         </screen>
1404         <screen>
1405 list            lists 10 source lines from current position
1406 list -          lists 10 source lines before current position
1407 list N          lists 10 source lines from line N in current file
1408 list &lt;path&gt;:N     lists 10 source lines from line N in file &lt;path&gt;
1409 list &lt;id&gt; lists 10 source lines of function &lt;id&gt;
1410 list * N        lists 10 source lines from address N
1411         </screen>
1412         <para>
1413           You can specify the end target (to change the 10 lines
1414           value) using the ','. For example:
1415         </para>
1416         <screen>
1417 list 123, 234   lists source lines from line 123 up to line 234 in
1418                 current file
1419 list foo.c:1,56 lists source lines from line 1 up to 56 in file foo.c
1420         </screen>
1421       </sect2>
1422
1423       <sect2>
1424         <title>Displaying</title>
1425
1426         <para>
1427           A display is an expression that's evaluated and printed
1428           after the execution of any <command>WineDbg</command>
1429           command.
1430         </para>
1431         <screen>
1432 display         lists the active displays
1433 info display    (same as above command)
1434 display &lt;expr&gt;    adds a display for expression &lt;expr&gt;
1435 display /fmt &lt;expr&gt;       adds a display for expression &lt;expr&gt;. Printing
1436                 evaluated &lt;expr&gt; is done using the given format (see
1437                 print command for more on formats)
1438 del display N   deletes display #N
1439 undisplay N     (same as del display)
1440         </screen>
1441       </sect2>
1442
1443       <sect2>
1444         <title>Disassembly</title>
1445
1446         <screen>
1447 disas           disassemble from current position
1448 disas &lt;expr&gt;      disassemble from address &lt;expr&gt;
1449 disas &lt;expr&gt;,&lt;expr&gt;disassembles code between addresses specified by
1450                 the two &lt;expr&gt;
1451         </screen>
1452       </sect2>
1453
1454       <sect2>
1455         <title>Information on Wine's internals</title>
1456
1457         <screen>
1458 info class &lt;id&gt;   prints information on Windows's class &lt;id&gt;
1459 walk class      lists all Windows' class registered in Wine
1460 info share      lists all the dynamic libraries loaded the debugged
1461                 program (including .so files, NE and PE DLLs)
1462 info module N   prints information on module of handle N
1463 walk module     lists all modules loaded by debugged program
1464 info queue N    prints information on Wine's queue N
1465 walk queue      lists all queues allocated in Wine
1466 info regs       prints the value of CPU register
1467 info segment N  prints information on segment N
1468 info segment    lists all allocated segments
1469 info stack      prints the values on top of the stack
1470 info map        lists all virtual mappings used by the debugged
1471                 program
1472 info wnd N      prints information of Window of handle N
1473 walk wnd        lists all the window hierarchy starting from the
1474                 desktop window
1475 walk wnd N      lists all the window hierarchy starting from the
1476                 window of handle N
1477 walk process    lists all w-processes in Wine session
1478 walk thread     lists all w-threads in Wine session
1479 walk modref     (no longer avail)
1480 walk exception  lists the exception frames (starting from current
1481                 stack frame)
1482         </screen>
1483       </sect2>
1484
1485       <sect2>
1486         <title>Memory (reading, writing, typing)</title>
1487
1488         <screen>
1489 x &lt;expr&gt;  examines memory at &lt;expr&gt; address
1490 x /fmt &lt;expr&gt;     examines memory at &lt;expr&gt; address using format /fmt
1491 print &lt;expr&gt;      prints the value of &lt;expr&gt; (possibly using its type)
1492 print /fmt &lt;expr&gt; prints the value of &lt;expr&gt; (possibly using its
1493                 type)
1494 set &lt;lval&gt;=&lt;expr&gt;   writes the value of &lt;expr&gt; in &lt;lval&gt;
1495 whatis &lt;expr&gt;     prints the C type of expression &lt;expr&gt;
1496         </screen>
1497         <para>
1498           <filename>/fmt</filename> is either <filename>/&lt;letter&gt;</filename> or
1499           <filename>/&lt;count&gt;&lt;letter&gt;</filename> letter can be
1500         </para>
1501         <screen>
1502 s =&gt; an ASCII string
1503 u =&gt; an Unicode UTF16 string
1504 i =&gt; instructions (disassemble)
1505 x =&gt; 32 bit unsigned hexadecimal integer
1506 d =&gt; 32 bit signed decimal integer
1507 w =&gt; 16 bit unsigned hexadecimal integer
1508 c =&gt; character (only printable 0x20-0x7f are actuallyprinted)
1509 b =&gt; 8 bit unsigned hexadecimal integer
1510 g =&gt; GUID
1511         </screen>
1512       </sect2>
1513
1514       <sect2>
1515         <title>Expressions</title>
1516
1517         <para>
1518           Expressions in Wine Debugger are mostly written in a C form. However, there
1519           are a few discrepancies:
1520           <itemizedlist>
1521             <listitem>
1522               <para>
1523                 Identifiers can take a '.' in their names. This allow
1524                 mainly to access symbols from different DLLs like
1525                 <function>USER32.DLL.CreateWindowA</function>.
1526               </para>
1527             </listitem>
1528             <listitem>
1529               <para>
1530                 The debugger will try to distinguish this writing with structure operations.
1531                 Therefore, you can only use the previous writing in operations manipulating
1532                 symbols ({break|watch}points, type information command...).
1533               </para>
1534             </listitem>
1535           </itemizedlist>
1536         </para>
1537       </sect2>
1538       <sect2>
1539           <title>Debug channels</title>
1540               <para>
1541                It is possible to turn on and off debug messages as you are debuging using
1542                the set command.
1543               </para>
1544             <screen>
1545 set + warn win  =&gt; turn on warn on 'win' channel
1546 set + win       =&gt; turn on warn/fixme/err/trace on 'win' channel
1547 set - win       =&gt; turn off warn/fixme/err/trace on 'win' channel
1548 set - fixme     =&gt; turn off the 'fixme' class
1549             </screen>
1550       </sect2>
1551
1552     </sect1>
1553
1554     <sect1 id="dbg-others">
1555       <title>Other debuggers</title>
1556
1557       <sect2>
1558         <title>GDB mode</title>
1559
1560         <para>
1561           WineDbg can act as a remote monitor for GDB. This allows to
1562           use all the power of GDB, but while debugging wine and/or
1563           any Win32 application. To enable this mode, just add
1564           <parameter>--gdb</parameter> to winedbg command line. You'll
1565           end up on a GDB prompt. You'll have to use the GDB commands
1566           (not the wine nes).
1567         </para>
1568
1569         <para>
1570           However, some limitation in GDB while debugging wine (see
1571           below) don't ppear in this mode:
1572           <itemizedlist>
1573             <listitem>
1574               <para>
1575                 GDB will correctly present Win32 thread
1576                 information and breakpoint behavior
1577               </para>
1578             </listitem>
1579             <listitem>
1580               <para>
1581                 Moreover, it also provides support for the Dwarf II
1582                 debug format (which became the default format (instead
1583                 of stabs) in gcc 3.1).
1584               </para>
1585             </listitem>
1586           </itemizedlist>
1587         </para>
1588
1589         <para>
1590           A few wine extensions available through the monitor command.
1591 <screen>
1592 monitor wnd           lists all window in the Wine session
1593 monitor proc          lists all processes in the Wine session
1594 monitor mem           displays memory mapping of debugged process
1595                       (doesn't work)
1596 </screen>
1597         </para>
1598       </sect2>
1599
1600       <sect2>
1601         <title>Using other Unix debuggers</title>
1602
1603         <para>
1604           You can also use other debuggers (like
1605           <command>gdb</command>), but you must be aware of a few
1606           items:
1607         </para>
1608         <para>
1609           You need to attach the unix debugger to the correct unix
1610           process (representing the correct windows thread) (you can
1611           "guess" it from a <command>ps fax</command> for example:
1612           When running the emulator, usually the first two
1613           <varname>upids</varname> are for the Windows' application
1614           running the desktop, the first thread of the application is
1615           generally the third <varname>upid</varname>; when running a
1616           Winelib program, the first thread of the application is
1617           generally the first <varname>upid</varname>)
1618         </para>
1619         <note>
1620           <para>
1621             Even if latest <command>gdb</command> implements the
1622             notion of threads, it won't work with Wine because the
1623             thread abstraction used for implementing Windows' thread
1624             is not 100% mapped onto the linux posix threads
1625             implementation. It means that you'll have to spawn a
1626             different <command>gdb</command> session for each Windows'
1627             thread you wish to debug.
1628           </para>
1629         </note>
1630
1631         <!-- *** Extra content spliced in from article by Andreas Mohr *** -->
1632         <para>
1633           Following text written by &name-andreas-mohr; <email>&email-andreas-mohr;</email>
1634         </para>
1635         <para>
1636           Here's how to get info about the current execution status of a
1637           certain Wine process:
1638         </para>
1639         <para>
1640           Change into your Wine source dir and enter:
1641         </para>
1642         <screen>
1643 $ gdb wine
1644         </screen>
1645         <para>
1646           Switch to another console and enter <command>ps ax | grep
1647             wine</command> to find all wine processes. Inside
1648           <command>gdb</command>, repeat for all Wine processes:
1649         </para>
1650         <screen>
1651 (gdb) attach <userinput>PID</userinput>
1652         </screen>
1653         <para>
1654           with <userinput>PID</userinput> being the process ID of one of
1655           the Wine processes.  Use
1656         </para>
1657         <screen>
1658 (gdb) bt
1659         </screen>
1660         <para>
1661           to get the backtrace of the current Wine process, i.e. the
1662           function call history.  That way you can find out what the
1663           current process is doing right now.  And then you can use
1664           several times:
1665         </para>
1666         <screen>
1667 (gdb) n
1668         </screen>
1669         <para>
1670           or maybe even
1671         </para>
1672         <screen>
1673 (gdb) b <userinput>SomeFunction</userinput>
1674         </screen>
1675         <para>
1676           and
1677         </para>
1678         <screen>
1679 (gdb) c
1680         </screen>
1681         <para>
1682           to set a breakpoint at a certain function and continue up to
1683           that function.  Finally you can enter
1684         </para>
1685         <screen>
1686 (gdb) detach
1687         </screen>
1688         <para>
1689           to detach from the Wine process.
1690         </para>
1691         <!-- *** End of xtra content *** -->
1692       </sect2>
1693
1694       <sect2>
1695         <title>Using other Windows debuggers</title>
1696
1697         <para>
1698           You can use any Windows' debugging API compliant debugger
1699           with Wine. Some reports have been made of success with
1700           VisualStudio debugger (in remote mode, only the hub runs
1701           in Wine). GoVest fully runs in Wine.
1702         </para>
1703       </sect2>
1704
1705       <sect2>
1706         <title>Main differences between winedbg and regular Unix debuggers</title>
1707         <table><title>Debuggers comparison</title>
1708           <tgroup cols=2 align="left">
1709             <tbody>
1710               <row>
1711                 <entry>WineDbg</entry><entry>gdb</entry>
1712               </row>
1713               <row>
1714                 <entry>
1715                   WineDbg debugs a Windows' process: the various
1716                   threads will be handled by the same WineDbg session,
1717                   and a breakpoint will be triggered for any thread of
1718                   the W-process
1719                 </entry>
1720                 <entry>
1721                   gdb debugs a Windows' thread: a separate gdb session
1722                   is needed for each thread of a Windows' process and
1723                   a breakpoint will be triggered only for the w-thread
1724                   debugged
1725                 </entry>
1726               </row>
1727               <row>
1728                 <entry>
1729                   WineDbg supports debug information from stabs
1730                   (standard Unix format) and Microsoft's C, CodeView,
1731                   .DBG
1732                 </entry>
1733                 <entry>
1734                   GDB supports debug information from stabs (standard
1735                   Unix format) and Dwarf II.
1736                 </entry>
1737               </row>
1738             </tbody>
1739           </tgroup>
1740         </table>
1741       </sect2>
1742     </sect1>
1743
1744
1745     <sect1 id="dbg-limits">
1746       <title>Limitations</title>
1747
1748       <itemizedlist>
1749         <listitem>
1750           <para>
1751             16 bit processes are not supported (but calls to 16 bit
1752             code in 32 bit  applications are).
1753           </para>
1754         </listitem>
1755         <listitem>
1756           <para>
1757             Function call in expression is no longer supported
1758           </para>
1759         </listitem>
1760       </itemizedlist>
1761     </sect1>
1762   </chapter>
1763
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