You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
174 lines
8.2 KiB
HTML
174 lines
8.2 KiB
HTML
4 years ago
|
<!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. Buying copies from GNU Press supports the FSF in
|
||
|
|
developing GNU and promoting software freedom." -->
|
||
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<title>Bootstrapping (Debugging with GDB)</title>
|
||
|
|
|
||
|
|
<meta name="description" content="Bootstrapping (Debugging with GDB)">
|
||
|
|
<meta name="keywords" content="Bootstrapping (Debugging with GDB)">
|
||
|
|
<meta name="resource-type" content="document">
|
||
|
|
<meta name="distribution" content="global">
|
||
|
|
<meta name="Generator" content="makeinfo">
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
||
|
|
<link href="index.html#Top" rel="start" title="Top">
|
||
|
|
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
||
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
||
|
|
<link href="Remote-Stub.html#Remote-Stub" rel="up" title="Remote Stub">
|
||
|
|
<link href="Debug-Session.html#Debug-Session" rel="next" title="Debug Session">
|
||
|
|
<link href="Stub-Contents.html#Stub-Contents" rel="prev" title="Stub Contents">
|
||
|
|
<style type="text/css">
|
||
|
|
<!--
|
||
|
|
a.summary-letter {text-decoration: none}
|
||
|
|
blockquote.indentedblock {margin-right: 0em}
|
||
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
||
|
|
blockquote.smallquotation {font-size: smaller}
|
||
|
|
div.display {margin-left: 3.2em}
|
||
|
|
div.example {margin-left: 3.2em}
|
||
|
|
div.lisp {margin-left: 3.2em}
|
||
|
|
div.smalldisplay {margin-left: 3.2em}
|
||
|
|
div.smallexample {margin-left: 3.2em}
|
||
|
|
div.smalllisp {margin-left: 3.2em}
|
||
|
|
kbd {font-style: oblique}
|
||
|
|
pre.display {font-family: inherit}
|
||
|
|
pre.format {font-family: inherit}
|
||
|
|
pre.menu-comment {font-family: serif}
|
||
|
|
pre.menu-preformatted {font-family: serif}
|
||
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
||
|
|
pre.smallexample {font-size: smaller}
|
||
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
||
|
|
pre.smalllisp {font-size: smaller}
|
||
|
|
span.nolinebreak {white-space: nowrap}
|
||
|
|
span.roman {font-family: initial; font-weight: normal}
|
||
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
||
|
|
ul.no-bullet {list-style: none}
|
||
|
|
-->
|
||
|
|
</style>
|
||
|
|
|
||
|
|
|
||
|
|
</head>
|
||
|
|
|
||
|
|
<body lang="en">
|
||
|
|
<a name="Bootstrapping"></a>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Debug-Session.html#Debug-Session" accesskey="n" rel="next">Debug Session</a>, Previous: <a href="Stub-Contents.html#Stub-Contents" accesskey="p" rel="prev">Stub Contents</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>
|
||
|
|
<hr>
|
||
|
|
<a name="What-You-Must-Do-for-the-Stub"></a>
|
||
|
|
<h4 class="subsection">20.5.2 What You Must Do for the Stub</h4>
|
||
|
|
|
||
|
|
<a name="index-remote-stub_002c-support-routines"></a>
|
||
|
|
<p>The debugging stubs that come with <small>GDB</small> are set up for a particular
|
||
|
|
chip architecture, but they have no information about the rest of your
|
||
|
|
debugging target machine.
|
||
|
|
</p>
|
||
|
|
<p>First of all you need to tell the stub how to communicate with the
|
||
|
|
serial port.
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dt><code>int getDebugChar()</code></dt>
|
||
|
|
<dd><a name="index-getDebugChar"></a>
|
||
|
|
<p>Write this subroutine to read a single character from the serial port.
|
||
|
|
It may be identical to <code>getchar</code> for your target system; a
|
||
|
|
different name is used to allow you to distinguish the two if you wish.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>void putDebugChar(int)</code></dt>
|
||
|
|
<dd><a name="index-putDebugChar"></a>
|
||
|
|
<p>Write this subroutine to write a single character to the serial port.
|
||
|
|
It may be identical to <code>putchar</code> for your target system; a
|
||
|
|
different name is used to allow you to distinguish the two if you wish.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<a name="index-control-C_002c-and-remote-debugging"></a>
|
||
|
|
<a name="index-interrupting-remote-targets"></a>
|
||
|
|
<p>If you want <small>GDB</small> to be able to stop your program while it is
|
||
|
|
running, you need to use an interrupt-driven serial driver, and arrange
|
||
|
|
for it to stop when it receives a <code>^C</code> (‘<samp>\003</samp>’, the control-C
|
||
|
|
character). That is the character which <small>GDB</small> uses to tell the
|
||
|
|
remote system to stop.
|
||
|
|
</p>
|
||
|
|
<p>Getting the debugging target to return the proper status to <small>GDB</small>
|
||
|
|
probably requires changes to the standard stub; one quick and dirty way
|
||
|
|
is to just execute a breakpoint instruction (the “dirty” part is that
|
||
|
|
<small>GDB</small> reports a <code>SIGTRAP</code> instead of a <code>SIGINT</code>).
|
||
|
|
</p>
|
||
|
|
<p>Other routines you need to supply are:
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dt><code>void exceptionHandler (int <var>exception_number</var>, void *<var>exception_address</var>)</code></dt>
|
||
|
|
<dd><a name="index-exceptionHandler"></a>
|
||
|
|
<p>Write this function to install <var>exception_address</var> in the exception
|
||
|
|
handling tables. You need to do this because the stub does not have any
|
||
|
|
way of knowing what the exception handling tables on your target system
|
||
|
|
are like (for example, the processor’s table might be in <small>ROM</small>,
|
||
|
|
containing entries which point to a table in <small>RAM</small>).
|
||
|
|
The <var>exception_number</var> specifies the exception which should be changed;
|
||
|
|
its meaning is architecture-dependent (for example, different numbers
|
||
|
|
might represent divide by zero, misaligned access, etc). When this
|
||
|
|
exception occurs, control should be transferred directly to
|
||
|
|
<var>exception_address</var>, and the processor state (stack, registers,
|
||
|
|
and so on) should be just as it is when a processor exception occurs. So if
|
||
|
|
you want to use a jump instruction to reach <var>exception_address</var>, it
|
||
|
|
should be a simple jump, not a jump to subroutine.
|
||
|
|
</p>
|
||
|
|
<p>For the 386, <var>exception_address</var> should be installed as an interrupt
|
||
|
|
gate so that interrupts are masked while the handler runs. The gate
|
||
|
|
should be at privilege level 0 (the most privileged level). The
|
||
|
|
<small>SPARC</small> and 68k stubs are able to mask interrupts themselves without
|
||
|
|
help from <code>exceptionHandler</code>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>void flush_i_cache()</code></dt>
|
||
|
|
<dd><a name="index-flush_005fi_005fcache"></a>
|
||
|
|
<p>On <small>SPARC</small> and <small>SPARCLITE</small> only, write this subroutine to flush the
|
||
|
|
instruction cache, if any, on your target machine. If there is no
|
||
|
|
instruction cache, this subroutine may be a no-op.
|
||
|
|
</p>
|
||
|
|
<p>On target machines that have instruction caches, <small>GDB</small> requires this
|
||
|
|
function to make certain that the state of your program is stable.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>You must also make sure this library routine is available:
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dt><code>void *memset(void *, int, int)</code></dt>
|
||
|
|
<dd><a name="index-memset"></a>
|
||
|
|
<p>This is the standard library function <code>memset</code> that sets an area of
|
||
|
|
memory to a known value. If you have one of the free versions of
|
||
|
|
<code>libc.a</code>, <code>memset</code> can be found there; otherwise, you must
|
||
|
|
either obtain it from your hardware manufacturer, or write your own.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>If you do not use the GNU C compiler, you may need other standard
|
||
|
|
library subroutines as well; this varies from one stub to another,
|
||
|
|
but in general the stubs are likely to use any of the common library
|
||
|
|
subroutines which <code><small>GCC</small></code> generates as inline code.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Debug-Session.html#Debug-Session" accesskey="n" rel="next">Debug Session</a>, Previous: <a href="Stub-Contents.html#Stub-Contents" accesskey="p" rel="prev">Stub Contents</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>
|