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<html><head><title>Gavare's eXperimental Emulator:&nbsp;&nbsp;&nbsp;GDB remote serial protocol connection</title>
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<b>Gavare's eXperimental Emulator:</b></font><br>
<font color="#000000" size="6"><b>GDB remote serial protocol connection</b>
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<p><br>
<h2>GDB remote serial protocol connection</h2>

<p>
<ul>
  <li><a href="#intro">Introduction</a>
  <li><a href="#prerequisites">Prerequisites</a>
  <li><a href="#example">Example session</a>
</ul>


<p><br>
<a name="intro"></a>
<h3>Introduction:</h3>

Starting with release 0.4.0, GXemul has (very rudimentary) GDB serial 
protocol support. This means that you can start up GDB, or a front-end 
program which in turn uses GDB, and connect it to a running GXemul 
instance.

<p>The GDB front-end I use in this example is the <a 
href="http://www.gnu.org/software/ddd/">Data Display Debugger (DDD)</a>.

<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<a href="20060504-gdb-64bit-mips.png"><img src="20060504-gdb-64bit-mips_small.png"></a>

<p>The screenshot above shows DDD connected to GXemul, running the Hello 
World demo program compiled for mips64-unknown-elf, on a FreeBSD/amd64 host.


<p><br>
<a name="prerequisites"></a>
<h3>Prerequisites:</h3>

<ul>
  <li>Build and install GDB for your target. You should use the same
        configuration as you did when you compiled your compiler (e.g.
        mips64-unknown-elf). Assuming you use <tt>~/crossdev</tt> for all
        your cross-development tools:<pre>
        # <b>wget <a href="http://ftp.gnu.org/gnu/gdb/gdb-6.4.tar.gz">http://ftp.gnu.org/gnu/gdb/gdb-6.4.tar.gz</a></b>
        # <b>tar zxf gdb-6.4.tar.gz</b>
        # <b>cd gdb-6.4</b>
        # <b>./configure --prefix=$HOME/crossdev --target=mips64-unknown-elf</b>
        # <b>gmake install</b>
</pre>
        Remember to include <tt>~/crossdev/bin</tt> in your PATH.
  <p>
  <li>Optionally, but highly recommended:  Install a front-end for GDB, such 
        as DDD. In FreeBSD, this is done by:<pre>
        # <b>pkg_add -r ddd</b>
</pre>
        Other operating systems that have DDD available as a pre-compiled
        package have similar methods of installing it; otherwise you could
        try compiling DDD from source.
</ul>

You can still run a bare GDB session without a GUI front-end if you like.


<p><br>
<a name="example"></a>
<h3>Example session:</h3>

<ol>
  <li>Start up GXemul, and tell it to wait for an incoming GDB connection
        on a certain port:<pre>
        # <b>gxemul -x -E testmips -G 10000 hello_mips</b>

</pre>
  <p>
  <li>Start the DDD, using a GDB configured for this specific target,
        and also give the name of the binary/kernel. (This binary
        should have been compiled with <tt>-g</tt>.)<pre>
        # <b>ddd --debugger mips64-unknown-elf-gdb hello_mips</b>

</pre>
  <p>
  <li>At the <tt>(gdb)</tt> prompt in DDD, type:<pre>
        (gdb) <b>target remote localhost:10000</b>

</pre>
  <p>
  <li>Press F9 (Continue) to start. Press ESC when you wish to interrupt.
        You can also use F5 (Step) to single-step one instruction at a time.
</ol>


<p><br><b><u>Notes:</u></b>

<p>
<ul>
        <li>The remote GDB functionality in GXemul is quite hack-ish, very
                unstable, very slow, and does not support any fancy features
                such as breakpoints or watchpoints yet.
        <li>For 64-bit MIPS targets, you might have to fiddle with
                MIPS-related GDB settings, to make GDB send correct commands
                to GXemul. Otherwise, GDB only sends the lowest 32 bits
                of memory addresses, which is incorrect.
        <li>When remote-debugging PowerPC targets using DDD, you might have to
                press F9 <i>twice</i> to get it to start. I am not sure why.
</ul>

</p>


<p><br>


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1	<html><head><title>Gavare's eXperimental Emulator:   GDB remote serial protocol connection</title>
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4	<table border=0 width=100% bgcolor="#d0d0d0"><tr>
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6	<td align="left" valign=center bgcolor="#d0efff"><font color="#6060e0" size="6">
7	<b>Gavare's eXperimental Emulator:</b></font><br>
8	<font color="#000000" size="6"><b>GDB remote serial protocol connection</b>
9	</font></td></tr></table></td></tr></table><p>
10
11	<!--
12
13	$Id: gdb_remote.html,v 1.11 2006/05/22 04:53:52 debug Exp $
14
15	Copyright (C) 2006 Anders Gavare. All rights reserved.
16
17	Redistribution and use in source and binary forms, with or without
18	modification, are permitted provided that the following conditions are met:
19
20	1. Redistributions of source code must retain the above copyright
21	notice, this list of conditions and the following disclaimer.
22	2. Redistributions in binary form must reproduce the above copyright
23	notice, this list of conditions and the following disclaimer in the
24	documentation and/or other materials provided with the distribution.
25	3. The name of the author may not be used to endorse or promote products
26	derived from this software without specific prior written permission.
27
28	THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
29	ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30	IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31	ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
32	FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33	DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34	OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35	HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36	LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37	OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38	SUCH DAMAGE.
39
40	-->
41
42	<a href="./">Back to the index</a>
43
44	<p><br>
45	<h2>GDB remote serial protocol connection</h2>
46
47	<p>
48	<ul>
49	<li><a href="#intro">Introduction</a>
50	<li><a href="#prerequisites">Prerequisites</a>
51	<li><a href="#example">Example session</a>
52	</ul>
53
54
55
56
57
58
59	<p><br>
60	<a name="intro"></a>
61	<h3>Introduction:</h3>
62
63	Starting with release 0.4.0, GXemul has (very rudimentary) GDB serial
64	protocol support. This means that you can start up GDB, or a front-end
65	program which in turn uses GDB, and connect it to a running GXemul
66	instance.
67
68	<p>The GDB front-end I use in this example is the <a
69	href="http://www.gnu.org/software/ddd/">Data Display Debugger (DDD)</a>.
70
71	<p>
72	<a href="20060504-gdb-64bit-mips.png"><img src="20060504-gdb-64bit-mips_small.png"></a>
73
74	<p>The screenshot above shows DDD connected to GXemul, running the Hello
75	World demo program compiled for mips64-unknown-elf, on a FreeBSD/amd64 host.
76
77
78
79
80
81
82	<p><br>
83	<a name="prerequisites"></a>
84	<h3>Prerequisites:</h3>
85
86	<ul>
87	<li>Build and install GDB for your target. You should use the same
88	configuration as you did when you compiled your compiler (e.g.
89	mips64-unknown-elf). Assuming you use <tt>~/crossdev</tt> for all
90	your cross-development tools:<pre>
91	# <b>wget <a href="http://ftp.gnu.org/gnu/gdb/gdb-6.4.tar.gz">http://ftp.gnu.org/gnu/gdb/gdb-6.4.tar.gz</a></b>
92	# <b>tar zxf gdb-6.4.tar.gz</b>
93	# <b>cd gdb-6.4</b>
94	# <b>./configure --prefix=$HOME/crossdev --target=mips64-unknown-elf</b>
95	# <b>gmake install</b>
96	</pre>
97	Remember to include <tt>~/crossdev/bin</tt> in your PATH.
98	<p>
99	<li>Optionally, but highly recommended: Install a front-end for GDB, such
100	as DDD. In FreeBSD, this is done by:<pre>
101	# <b>pkg_add -r ddd</b>
102	</pre>
103	Other operating systems that have DDD available as a pre-compiled
104	package have similar methods of installing it; otherwise you could
105	try compiling DDD from source.
106	</ul>
107
108	You can still run a bare GDB session without a GUI front-end if you like.
109
110
111
112
113
114	<p><br>
115	<a name="example"></a>
116	<h3>Example session:</h3>
117
118	<ol>
119	<li>Start up GXemul, and tell it to wait for an incoming GDB connection
120	on a certain port:<pre>
121	# <b>gxemul -x -E testmips -G 10000 hello_mips</b>
122
123	</pre>
124	<p>
125	<li>Start the DDD, using a GDB configured for this specific target,
126	and also give the name of the binary/kernel. (This binary
127	should have been compiled with <tt>-g</tt>.)<pre>
128	# <b>ddd --debugger mips64-unknown-elf-gdb hello_mips</b>
129
130	</pre>
131	<p>
132	<li>At the <tt>(gdb)</tt> prompt in DDD, type:<pre>
133	(gdb) <b>target remote localhost:10000</b>
134
135	</pre>
136	<p>
137	<li>Press F9 (Continue) to start. Press ESC when you wish to interrupt.
138	You can also use F5 (Step) to single-step one instruction at a time.
139	</ol>
140
141
142
143	<p><br><b><u>Notes:</u></b>
144
145	<p>
146	<ul>
147	<li>The remote GDB functionality in GXemul is quite hack-ish, very
148	unstable, very slow, and does not support any fancy features
149	such as breakpoints or watchpoints yet.
150	<li>For 64-bit MIPS targets, you might have to fiddle with
151	MIPS-related GDB settings, to make GDB send correct commands
152	to GXemul. Otherwise, GDB only sends the lowest 32 bits
153	of memory addresses, which is incorrect.
154	<li>When remote-debugging PowerPC targets using DDD, you might have to
155	press F9 <i>twice</i> to get it to start. I am not sure why.
156	</ul>
157
158	</p>
159
160
161	<p><br>
162
163
164	</body>
165	</html>