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<h4 class="subsection">21.1.5 Features for Debugging MS Windows PE Executables</h4>

<p><a name="index-MS-Windows-debugging-1207"></a><a name="index-native-Cygwin-debugging-1208"></a><a name="index-Cygwin_002dspecific-commands-1209"></a>
<span class="sc">gdb</span> supports native debugging of MS Windows programs, including
DLLs with and without symbolic debugging information.

   <p><a name="index-Ctrl_002dBREAK_002c-MS_002dWindows-1210"></a><a name="index-interrupt-debuggee-on-MS_002dWindows-1211"></a>MS-Windows programs that call <code>SetConsoleMode</code> to switch off the
special meaning of the &lsquo;<samp><span class="samp">Ctrl-C</span></samp>&rsquo; keystroke cannot be interrupted
by typing <kbd>C-c</kbd>.  For this reason, <span class="sc">gdb</span> on MS-Windows
supports <kbd>C-&lt;BREAK&gt;</kbd> as an alternative interrupt key
sequence, which can be used to interrupt the debuggee even if it
ignores <kbd>C-c</kbd>.

   <p>There are various additional Cygwin-specific commands, described in
this section.  Working with DLLs that have no debugging symbols is
described in <a href="Non_002ddebug-DLL-Symbols.html#Non_002ddebug-DLL-Symbols">Non-debug DLL Symbols</a>.

     
<a name="index-info-w32-1212"></a>
<dl><dt><code>info w32</code><dd>This is a prefix of MS Windows-specific commands which print
information about the target system and important OS structures.

     <br><dt><code>info w32 selector</code><dd>This command displays information returned by
the Win32 API <code>GetThreadSelectorEntry</code> function. 
It takes an optional argument that is evaluated to
a long value to give the information about this given selector. 
Without argument, this command displays information
about the six segment registers.

     <br><dt><code>info w32 thread-information-block</code><dd>This command displays thread specific information stored in the
Thread Information Block (readable on the X86 CPU family using <code>$fs</code>
selector for 32-bit programs and <code>$gs</code> for 64-bit programs).

     <p><a name="index-info-dll-1213"></a><br><dt><code>info dll</code><dd>This is a Cygwin-specific alias of <code>info shared</code>.

     <p><a name="index-dll_002dsymbols-1214"></a><br><dt><code>dll-symbols</code><dd>This command loads symbols from a dll similarly to
add-sym command but without the need to specify a base address.

     <p><a name="index-set-cygwin_002dexceptions-1215"></a><a name="index-debugging-the-Cygwin-DLL-1216"></a><a name="index-Cygwin-DLL_002c-debugging-1217"></a><br><dt><code>set cygwin-exceptions </code><var>mode</var><dd>If <var>mode</var> is <code>on</code>, <span class="sc">gdb</span> will break on exceptions that
happen inside the Cygwin DLL.  If <var>mode</var> is <code>off</code>,
<span class="sc">gdb</span> will delay recognition of exceptions, and may ignore some
exceptions which seem to be caused by internal Cygwin DLL
&ldquo;bookkeeping&rdquo;.  This option is meant primarily for debugging the
Cygwin DLL itself; the default value is <code>off</code> to avoid annoying
<span class="sc">gdb</span> users with false <code>SIGSEGV</code> signals.

     <p><a name="index-show-cygwin_002dexceptions-1218"></a><br><dt><code>show cygwin-exceptions</code><dd>Displays whether <span class="sc">gdb</span> will break on exceptions that happen
inside the Cygwin DLL itself.

     <p><a name="index-set-new_002dconsole-1219"></a><br><dt><code>set new-console </code><var>mode</var><dd>If <var>mode</var> is <code>on</code> the debuggee will
be started in a new console on next start. 
If <var>mode</var> is <code>off</code>, the debuggee will
be started in the same console as the debugger.

     <p><a name="index-show-new_002dconsole-1220"></a><br><dt><code>show new-console</code><dd>Displays whether a new console is used
when the debuggee is started.

     <p><a name="index-set-new_002dgroup-1221"></a><br><dt><code>set new-group </code><var>mode</var><dd>This boolean value controls whether the debuggee should
start a new group or stay in the same group as the debugger. 
This affects the way the Windows OS handles
&lsquo;<samp><span class="samp">Ctrl-C</span></samp>&rsquo;.

     <p><a name="index-show-new_002dgroup-1222"></a><br><dt><code>show new-group</code><dd>Displays current value of new-group boolean.

     <p><a name="index-set-debugevents-1223"></a><br><dt><code>set debugevents</code><dd>This boolean value adds debug output concerning kernel events related
to the debuggee seen by the debugger.  This includes events that
signal thread and process creation and exit, DLL loading and
unloading, console interrupts, and debugging messages produced by the
Windows <code>OutputDebugString</code> API call.

     <p><a name="index-set-debugexec-1224"></a><br><dt><code>set debugexec</code><dd>This boolean value adds debug output concerning execute events
(such as resume thread) seen by the debugger.

     <p><a name="index-set-debugexceptions-1225"></a><br><dt><code>set debugexceptions</code><dd>This boolean value adds debug output concerning exceptions in the
debuggee seen by the debugger.

     <p><a name="index-set-debugmemory-1226"></a><br><dt><code>set debugmemory</code><dd>This boolean value adds debug output concerning debuggee memory reads
and writes by the debugger.

     <p><a name="index-set-shell-1227"></a><br><dt><code>set shell</code><dd>This boolean values specifies whether the debuggee is called
via a shell or directly (default value is on).

     <p><a name="index-show-shell-1228"></a><br><dt><code>show shell</code><dd>Displays if the debuggee will be started with a shell.

   </dl>

<ul class="menu">
<li><a accesskey="1" href="Non_002ddebug-DLL-Symbols.html#Non_002ddebug-DLL-Symbols">Non-debug DLL Symbols</a>:   Support for DLLs without debugging symbols
</ul>

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