<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <!-- Copyright (C) 1988-2019 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Free Software" and "Free Software Needs Free Documentation", with the Front-Cover Texts being "A GNU Manual," and with the Back-Cover Texts as in (a) below. (a) The FSF's Back-Cover Text is: "You are free to copy and modify this GNU Manual. 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You must call this subroutine explicitly in your program’s startup code. </p> </dd> <dt><code>handle_exception</code></dt> <dd><a name="index-handle_005fexception"></a> <a name="index-remote-serial-stub_002c-main-routine"></a> <p>This is the central workhorse, but your program never calls it explicitly—the setup code arranges for <code>handle_exception</code> to run when a trap is triggered. </p> <p><code>handle_exception</code> takes control when your program stops during execution (for example, on a breakpoint), and mediates communications with <small>GDB</small> on the host machine. This is where the communications protocol is implemented; <code>handle_exception</code> acts as the <small>GDB</small> representative on the target machine. It begins by sending summary information on the state of your program, then continues to execute, retrieving and transmitting any information <small>GDB</small> needs, until you execute a <small>GDB</small> command that makes your program resume; at that point, <code>handle_exception</code> returns control to your own code on the target machine. </p> </dd> <dt><code>breakpoint</code></dt> <dd><a name="index-breakpoint-subroutine_002c-remote"></a> <p>Use this auxiliary subroutine to make your program contain a breakpoint. Depending on the particular situation, this may be the only way for <small>GDB</small> to get control. For instance, if your target machine has some sort of interrupt button, you won’t need to call this; pressing the interrupt button transfers control to <code>handle_exception</code>—in effect, to <small>GDB</small>. On some machines, simply receiving characters on the serial port may also trigger a trap; again, in that situation, you don’t need to call <code>breakpoint</code> from your own program—simply running ‘<samp>target remote</samp>’ from the host <small>GDB</small> session gets control. </p> <p>Call <code>breakpoint</code> if none of these is true, or if you simply want to make certain your program stops at a predetermined point for the start of your debugging session. </p></dd> </dl> <hr> <div class="header"> <p> Next: <a href="Bootstrapping.html#Bootstrapping" accesskey="n" rel="next">Bootstrapping</a>, Up: <a href="Remote-Stub.html#Remote-Stub" accesskey="u" rel="up">Remote Stub</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> </div> </body> </html>