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<b>Gavare's eXperimental Emulator:&nbsp;&nbsp;&nbsp;</b></font>
<font color="#000000" size="6"><b>Introduction</b>
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<p><br>
<h2>Introduction</h2>

<p>
<ul>
  <li><a href="#overview">Overview</a>
  <li><a href="#free">Is GXemul Free software?</a>
  <li><a href="#build">How to compile/build the emulator</a>
  <li><a href="#run">How to run the emulator</a>
  <li><a href="#cpus">Which CPU types does GXemul emulate?</a>
  <li><a href="#accuracy">Emulation accuracy</a>
  <li><a href="#emulmodes">Which machines does GXemul emulate?</a>
  <li><a href="#guestos">Which guest OSes are possible to run in GXemul?</a>
</ul>


<p><br>
<a name="overview"></a>
<h3>Overview:</h3>

GXemul is an experimental instruction-level machine emulator. Several
emulation modes are available. In some modes, processors and surrounding
hardware components are emulated well enough to let unmodified operating
systems (e.g. NetBSD) run as if they were running on a real machine.

<p>The processor architecture best emulated by GXemul is MIPS, but other
architectures are also partially emulated.

<p>Devices and CPUs are not simulated with 100% accuracy. They are only
``faked'' well enough to make operating systems (e.g. NetBSD) run without
complaining too much. Still, the emulator could be of interest for
academic research and experiments, such as when learning how to write
operating system code.

<p>The emulator is written in C, does not depend on external libraries
(except X11, but that is optional), and should compile and run on most
Unix-like systems. If it doesn't, then that is a bug.

<p>The emulator contains code which tries to emulate the workings of CPUs
and surrounding hardware found in real machines, but it does not contain
any ROM code. You will need some form of program (in binary form) to run
in the emulator. For many emulation modes, PROM calls are handled by the
emulator itself, so you do not need to use any ROM image at all.

<p>You can use pre-compiled kernels (for example NetBSD kernels, or
Linux), or other programs that are in binary format, and in some cases
even actual ROM images. A couple of different file formats are supported
(ELF, a.out, ECOFF, SREC, and raw binaries).

<p>If you do not have a kernel as a separate file, but you have a bootable
disk image, then it is sometimes possible to boot directly from that
image. (This works for example with DECstation emulation, or when booting
from ISO9660 CDROM images.)


<p><br>
<a name="free"></a>
<h3>Is GXemul Free software?</h3>

Yes. I have released GXemul under a Free license. The code in GXemul is
Copyrighted software, it is <i>not</i> public domain. (If this is
confusing to you, you might want to read up on the definitions of the
four freedoms associated with Free software, <a
href="http://www.gnu.org/philosophy/free-sw.html">http://www.gnu.org/philosophy/free-sw.html</a>.)

<p>The code I have written is released under a 3-clause BSD-style license
(or "revised BSD-style" if one wants to use <a
href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>). Apart from
the code I have written, some files are copied from other sources such as
NetBSD, for example header files containing symbolic names of bitfields in
device registers. They are also covered by similar licenses, but with some
additional clauses. The main point, however, is that the licenses require
that the original Copyright and license terms are included when you make a
copy or modification.

<p>If you plan to redistribute GXemul <i>without</i> supplying the source
code, then you need to comply with each individual source file some other
way, for example by writing additional documentation containing copyright
notes. I have not done this, since I do not plan on making distributions
without source code. You need to check all individual files for details.
The "easiest way out" if you plan to redistribute code from GXemul is, of
course, to let it remain open source and simply supply the source code.

<p>(If a stable, unmodified release of GXemul is packaged into binary form,
and it is clear which version of GXemul was used to build the package, 
then it can be argued that the source code is available, just not in that 
specific package. Common sense should be used in this case, and not 
pedanticism.)


<p><br>
<a name="build"></a>
<h3>How to compile/build the emulator:</h3>

Uncompress the .tar.gz distribution file, and run
<pre>
        $ <b>./configure</b>
        $ <b>make</b>
</pre>

<p>This should work on most Unix-like systems. If it doesn't, then
mail me a bug report.

<p>The emulator's performance is highly dependent on both runtime settings
and on compiler settings, so you might want to experiment with different
CC and CFLAGS environment variable values. For example, on a modern PC,
you could try the following:
<p><pre>
        $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>
        $ <b>make</b>
</pre>


<p><br>
<a name="run"></a>
<h3>How to run the emulator:</h3>

Once you have built GXemul, running it should be rather straight-forward.
Running <tt><b>gxemul</b></tt> without arguments (or with the
<b><tt>-h</tt></b> or <b><tt>-H</tt></b> command line options) will
display a help message.

<p>
To get some ideas about what is possible to run in the emulator, please 
read the section about <a href="guestoses.html">installing "guest" 
operating systems</a>. If you are interested in using the emulator to 
develop code on your own, then you should also read the section about
<a href="experiments.html#hello">Hello World</a>.

<p>
To exit the emulator, type CTRL-C to enter the 
single-step debugger, and then type <tt><b>quit</b></tt>.

<p>
If you are starting an emulation by entering settings directly on the 
command line, and you are not using the <tt><b>-x</b></tt> option, then all 
terminal input and output will go to the main controlling terminal.
CTRL-C is used to break into the debugger, so in order to send CTRL-C to 
the running (emulated) program, you may use CTRL-B.
(This should be a reasonable compromise to allow the emulator to be usable
even on systems without X Windows.)

<p>
There is no way to send an actual CTRL-B to the emulated program, when
typing in the main controlling terminal window. The solution is to either
use <a href="configfiles.html">configuration files</a>, or use
<tt><b>-x</b></tt>. Both these solutions cause new xterms to be opened for 
each emulated serial port that is written to. CTRL-B and CTRL-C both have 
their original meaning in those xterm windows.


<p><br>
<a name="cpus"></a>
<h3>Which CPU types does GXemul emulate?</h3>

<h4>MIPS:</h4>

Emulation of R4000, which is a 64-bit CPU, was my initial goal.
R2000/R3000-like CPUs (32-bit), R1x000, and generic MIPS32/MIPS64-style
CPUs are also emulated, and are hopefully almost as stable as the R4000 
emulation.

<p>I have written an experimental dynamic binary translation subsystem.
This gives higher total performance than interpreting one instruction at a
time and executing it. (If you wish to disable bintrans, add <b>-B</b> to
the command line.)

<h4>ARM:</h4>

The ARM CPU emulation is good enough to run NetBSD/cats and OpenBSD/cats
(almost bugfree :-), but it is not as tested or fine-tuned as the MIPS
emulation.

<h4>Other CPU types:</h4>

Some other CPU architectures can also be partially emulated. These are not
working well enough yet to run guest operating systems.


<p><br>
<a name="accuracy"></a>
<h3>Emulation accuracy:</h3>

GXemul is an instruction-level emulator; things that would happen in
several steps within a real CPU are not taken into account (eg. pipe-line
stalls or out-of-order execution). Still, instruction-level accuracy seems
to be enough to be able to run complete guest operating systems inside the
emulator.

<p>Caches are by default not emulated. In some cases, the existance of
caches is "faked" to let operating systems think that they are there.
(There is some old code for R2000/R3000 caches, but it has probably
suffered from bitrot by now.)

<p>The emulator is <i>not</i> timing-accurate. It can be run in a
"deterministic" mode, <tt><b>-D</b></tt>. The meaning of deterministic is
simply that running two emulations with the same settings will result in
identical runs. Obviously, this requires that no user interaction is
taking place, and that clock speeds are fixed with the <tt><b>-I</b></tt>
option. (Deterministic in this case does <i>not</i> mean that the
emulation will be identical to some actual real-world machine.)


<p><br>
<a name="emulmodes"></a>
<h3>Which machines does GXemul emulate?</h3>

A few different machine types are emulated. The following machine types 
are emulated well enough to run at least one "guest OS":

<p>
<ul>
  <li><b><u>MIPS</u></b>
  <ul>
    <li><b>DECstation 5000/200</b>&nbsp;&nbsp;("3max")
        <br>Serial controller (including keyboard and mouse), ethernet,
        SCSI, and graphical framebuffers.
    <p>
    <li><b>Acer Pica-61</b>&nbsp;&nbsp;(an ARC machine)
        <br>Serial controller, "VGA" text console, and SCSI.
    <p>
    <li><b>NEC MobilePro 770, 780, 800, and 880</b>&nbsp;&nbsp;(HPCmips machines)
        <br>Framebuffer, keyboard, and a PCMCIA IDE controller.
    <p>
    <li><b>Cobalt</b>
        <br>Serial controller and PCI IDE.
    <p>
    <li><b>Malta (evbmips)</b>
        <br>Serial controller and PCI IDE.
    <p>
    <li><b>SGI O2 ("IP32")</b>
        <br>Serial controller and ethernet.&nbsp;&nbsp;<small>(Enough for
        root-on-nfs, but not for disk boot.)</small>
  </ul>
  <p>
  <li><b><u>ARM</u></b>
  <ul>
    <li><b>CATS</b>
        <br>VGA and PCI IDE.
  </ul>
</ul>

<p>There is code in GXemul for emulation of many other machine types; the
degree to which these work range from almost being able to run a complete
OS, to almost completely unsupported (perhaps just enough support to
output a few boot messages via serial console).

<p>In addition to emulating real machines, there is also a "test-machine".
A test-machine consists of one or more CPUs and a few experimental devices
such as:

<p>
<ul>
  <li>a console I/O device (putchar() and getchar()...)
  <li>an inter-processor communication device, for SMP experiments
  <li>a very simple linear framebuffer device (for graphics output)
  <li>a simple SCSI disk controller
  <li>a simple ethernet controller
</ul>

<p>This mode is useful if you wish to run experimental code, but do not
wish to target any specific real-world machine type, for example for
educational purposes.

<p>You can read more about these experimental devices <a
href="experiments.html#expdevices">here</a>.


<p><br>
<a name="guestos"></a>
<h3>Which guest OSes are possible to run in GXemul?</h3>

This table lists the guest OSes that run well enough to be considered
working in the emulator. They can boot from a harddisk image and be
interacted with similar to a real machine.

<p>
<center><table border="0">
        <tr>
          <td width="10"></td>
          <td align="center"><a href="20050317-example.png"><img src="20050317-example_small.png"></a></td>
          <td width="15"></td>
          <td><a href="http://www.netbsd.org/Ports/pmax/">NetBSD/pmax</a>
                <br>DECstation 5000/200</td>
          <td width="30"></td>
          <td align="center"><a href="20041024-netbsd-arc-installed.gif"><img src="20041024-netbsd-arc-installed_small.gif"></a></td>
          <td width="15"></td>
          <td><a href="http://www.netbsd.org/Ports/arc/">NetBSD/arc</a>
                <br>Acer Pica-61</td>

        </tr>

        <tr><td height="10"></td></tr>

        <tr>
          <td></td>
          <td align="center"><a href="openbsd-pmax-20040710.png"><img src="openbsd-pmax-20040710_small.png"></a></td>
          <td></td>
          <td><a href="http://www.openbsd.org/pmax.html">OpenBSD/pmax</a>
                <br>DECstation 5000/200</td>
          <td></td>
          <td align="center"><a href="20041024-openbsd-arc-installed.gif"><img src="20041024-openbsd-arc-installed_small.gif"></a></td>
          <td></td>
          <td><a href="http://www.openbsd.org/arc.html">OpenBSD/arc</a>
                <br>Acer Pica-61</td>
        </tr>

        <tr><td height="10"></td></tr>

        <tr>
          <td></td>
          <td align="center"><a href="ultrix4.5-20040706.png"><img src="ultrix4.5-20040706_small.gif"></a></td>
          <td></td>
          <td>Ultrix/RISC<br>DECstation 5000/200</td>
          <td></td>
          <td align="center"><a href="20041213-debian_4.png"><img src="20041213-debian_4_small.gif"></a></td>
          <td></td>
          <td><a href="http://www.debian.org/">Debian&nbsp;GNU/Linux</a>&nbsp;<super>*</super>
                <br>DECstation 5000/200</td>
        </tr>

        <tr><td height="10"></td></tr>

        <tr>
          <td></td>
          <td align="center"><a href="sprite-20040711.png"><img src="sprite-20040711_small.png"></a></td>
          <td></td>
          <td><a href="http://www.cs.berkeley.edu/projects/sprite/retrospective.html">Sprite</a>
                <br>DECstation 5000/200</td>
          <td></td>
          <td align="center"><a href="20041129-redhat_mips.png"><img src="20041129-redhat_mips_small.png"></a></td>
          <td></td>
          <td>Redhat&nbsp;Linux&nbsp;<super>*</super>
                <br>DECstation 5000/200</td>
        </tr>

        <tr><td height="10"></td></tr>

        <tr>
          <td></td>
          <td align="center"><a href="20050427-netbsd-hpcmips-2.png"><img src="20050427-netbsd-hpcmips-2_small.png"></a></td>
          <td></td>
          <td><a href="http://www.netbsd.org/Ports/hpcmips/">NetBSD/hpcmips</a>
                <br>NEC MobilePro 770, 780, 800, 880</td>
          <td></td>
          <td align="center"><a href="20050413-netbsd-cobalt.png"><img src="20050413-netbsd-cobalt_small.png"></a></td>
          <td></td>
          <td><a href="http://www.netbsd.org/Ports/cobalt/">NetBSD/cobalt</a>
                <br>Cobalt</td>
        </tr>

        <tr><td height="10"></td></tr>

        <tr>
          <td></td>
          <td align="center"><a href="20050626-netbsd-sgimips-netboot.png"><img src="20050626-netbsd-sgimips-netboot_small.png"></a></td>
          <td></td>
          <td><a href="http://www.netbsd.org/Ports/sgimips/">NetBSD/sgimips</a>
                <br>SGI O2 ("IP32")</td>
          <td></td>
          <td align="center"><a href="20050622-netbsd-evbmips-malta.png"><img src="20050622-netbsd-evbmips-malta_small.png"></a></td>
          <td></td>
          <td><a href="http://www.netbsd.org/Ports/evbmips/">NetBSD/evbmips</a>
                <br>5Kc (and 4Kc) Malta<br>evaluation boards</td>
          <td></td>
        </tr>

        <tr><td height="10"></td></tr>

        <tr>
          <td></td>
          <td align="center"><a href="20051007-netbsd-cats-installed.png"><img src="20051007-netbsd-cats-installed_small.png"></a></td>
          <td></td>
          <td><a href="http://www.netbsd.org/Ports/cats/">NetBSD/cats</a>
                <br>CATS</td>
          <td></td>
          <td align="center"><a href="20051007-openbsd-cats-installed.png"><img src="20051007-openbsd-cats-installed_small.png"></a></td>
          <td></td>
          <td><a href="http://www.openbsd.org/cats.html">OpenBSD/cats</a>
                <br>CATS</td>
          <td></td>
        </tr>

</table></center>


<p><br>

<super>*</super> Although Linux runs under DECstation emulation, the
default 2.4.27 kernel in Debian GNU/Linux does not support keyboards on
the 5000/200 (the specific DECstation model being emulated), so when the
login prompt is reached you cannot interact with the system. Kaj-Michael
Lang has compiled and made available a newer kernel from the current
mips-linux development tree. You can find it here: <a
href="http://home.tal.org/~milang/o2/kernels/">http://home.tal.org/~milang/o2/kernels</a>/<a
href="http://home.tal.org/~milang/o2/kernels/vmlinux-2.4.29-rc2-r3k-mipsel-decstation">vmlinux-2.4.29-rc2-r3k-mipsel-decstation</a>
This newer kernel supports keyboard input, but it does not have Debian's
ethernet patches, so you will not be able to use keyboard/framebuffer
<i>and</i> networking at the same time.


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41
42	<a href="./">Back to the index</a>
43
44	<p><br>
45	<h2>Introduction</h2>
46
47	<p>
48	<ul>
49	<li><a href="#overview">Overview</a>
50	<li><a href="#free">Is GXemul Free software?</a>
51	<li><a href="#build">How to compile/build the emulator</a>
52	<li><a href="#run">How to run the emulator</a>
53	<li><a href="#cpus">Which CPU types does GXemul emulate?</a>
54	<li><a href="#accuracy">Emulation accuracy</a>
55	<li><a href="#emulmodes">Which machines does GXemul emulate?</a>
56	<li><a href="#guestos">Which guest OSes are possible to run in GXemul?</a>
57	</ul>
58
59
60
61
62
63	<p><br>
64	<a name="overview"></a>
65	<h3>Overview:</h3>
66
67	GXemul is an experimental instruction-level machine emulator. Several
68	emulation modes are available. In some modes, processors and surrounding
69	hardware components are emulated well enough to let unmodified operating
70	systems (e.g. NetBSD) run as if they were running on a real machine.
71
72	<p>The processor architecture best emulated by GXemul is MIPS, but other
73	architectures are also partially emulated.
74
75	<p>Devices and CPUs are not simulated with 100% accuracy. They are only
76	``faked'' well enough to make operating systems (e.g. NetBSD) run without
77	complaining too much. Still, the emulator could be of interest for
78	academic research and experiments, such as when learning how to write
79	operating system code.
80
81	<p>The emulator is written in C, does not depend on external libraries
82	(except X11, but that is optional), and should compile and run on most
83	Unix-like systems. If it doesn't, then that is a bug.
84
85	<p>The emulator contains code which tries to emulate the workings of CPUs
86	and surrounding hardware found in real machines, but it does not contain
87	any ROM code. You will need some form of program (in binary form) to run
88	in the emulator. For many emulation modes, PROM calls are handled by the
89	emulator itself, so you do not need to use any ROM image at all.
90
91	<p>You can use pre-compiled kernels (for example NetBSD kernels, or
92	Linux), or other programs that are in binary format, and in some cases
93	even actual ROM images. A couple of different file formats are supported
94	(ELF, a.out, ECOFF, SREC, and raw binaries).
95
96	<p>If you do not have a kernel as a separate file, but you have a bootable
97	disk image, then it is sometimes possible to boot directly from that
98	image. (This works for example with DECstation emulation, or when booting
99	from ISO9660 CDROM images.)
100
101
102
103
104
105
106
107
108	<p><br>
109	<a name="free"></a>
110	<h3>Is GXemul Free software?</h3>
111
112	Yes. I have released GXemul under a Free license. The code in GXemul is
113	Copyrighted software, it is <i>not</i> public domain. (If this is
114	confusing to you, you might want to read up on the definitions of the
115	four freedoms associated with Free software, <a
116	href="http://www.gnu.org/philosophy/free-sw.html">http://www.gnu.org/philosophy/free-sw.html</a>.)
117
118	<p>The code I have written is released under a 3-clause BSD-style license
119	(or "revised BSD-style" if one wants to use <a
120	href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>). Apart from
121	the code I have written, some files are copied from other sources such as
122	NetBSD, for example header files containing symbolic names of bitfields in
123	device registers. They are also covered by similar licenses, but with some
124	additional clauses. The main point, however, is that the licenses require
125	that the original Copyright and license terms are included when you make a
126	copy or modification.
127
128	<p>If you plan to redistribute GXemul <i>without</i> supplying the source
129	code, then you need to comply with each individual source file some other
130	way, for example by writing additional documentation containing copyright
131	notes. I have not done this, since I do not plan on making distributions
132	without source code. You need to check all individual files for details.
133	The "easiest way out" if you plan to redistribute code from GXemul is, of
134	course, to let it remain open source and simply supply the source code.
135
136	<p>(If a stable, unmodified release of GXemul is packaged into binary form,
137	and it is clear which version of GXemul was used to build the package,
138	then it can be argued that the source code is available, just not in that
139	specific package. Common sense should be used in this case, and not
140	pedanticism.)
141
142
143
144
145
146
147	<p><br>
148	<a name="build"></a>
149	<h3>How to compile/build the emulator:</h3>
150
151	Uncompress the .tar.gz distribution file, and run
152	<pre>
153	$ <b>./configure</b>
154	$ <b>make</b>
155	</pre>
156
157	<p>This should work on most Unix-like systems. If it doesn't, then
158	mail me a bug report.
159
160	<p>The emulator's performance is highly dependent on both runtime settings
161	and on compiler settings, so you might want to experiment with different
162	CC and CFLAGS environment variable values. For example, on a modern PC,
163	you could try the following:
164	<p><pre>
165	$ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>
166	$ <b>make</b>
167	</pre>
168
169
170
171
172
173
174
175	<p><br>
176	<a name="run"></a>
177	<h3>How to run the emulator:</h3>
178
179	Once you have built GXemul, running it should be rather straight-forward.
180	Running <tt><b>gxemul</b></tt> without arguments (or with the
181	<b><tt>-h</tt></b> or <b><tt>-H</tt></b> command line options) will
182	display a help message.
183
184	<p>
185	To get some ideas about what is possible to run in the emulator, please
186	read the section about <a href="guestoses.html">installing "guest"
187	operating systems</a>. If you are interested in using the emulator to
188	develop code on your own, then you should also read the section about
189	<a href="experiments.html#hello">Hello World</a>.
190
191	<p>
192	To exit the emulator, type CTRL-C to enter the
193	single-step debugger, and then type <tt><b>quit</b></tt>.
194
195	<p>
196	If you are starting an emulation by entering settings directly on the
197	command line, and you are not using the <tt><b>-x</b></tt> option, then all
198	terminal input and output will go to the main controlling terminal.
199	CTRL-C is used to break into the debugger, so in order to send CTRL-C to
200	the running (emulated) program, you may use CTRL-B.
201	(This should be a reasonable compromise to allow the emulator to be usable
202	even on systems without X Windows.)
203
204	<p>
205	There is no way to send an actual CTRL-B to the emulated program, when
206	typing in the main controlling terminal window. The solution is to either
207	use <a href="configfiles.html">configuration files</a>, or use
208	<tt><b>-x</b></tt>. Both these solutions cause new xterms to be opened for
209	each emulated serial port that is written to. CTRL-B and CTRL-C both have
210	their original meaning in those xterm windows.
211
212
213
214
215
216	<p><br>
217	<a name="cpus"></a>
218	<h3>Which CPU types does GXemul emulate?</h3>
219
220	<h4>MIPS:</h4>
221
222	Emulation of R4000, which is a 64-bit CPU, was my initial goal.
223	R2000/R3000-like CPUs (32-bit), R1x000, and generic MIPS32/MIPS64-style
224	CPUs are also emulated, and are hopefully almost as stable as the R4000
225	emulation.
226
227	<p>I have written an experimental dynamic binary translation subsystem.
228	This gives higher total performance than interpreting one instruction at a
229	time and executing it. (If you wish to disable bintrans, add <b>-B</b> to
230	the command line.)
231
232	<h4>ARM:</h4>
233
234	The ARM CPU emulation is good enough to run NetBSD/cats and OpenBSD/cats
235	(almost bugfree :-), but it is not as tested or fine-tuned as the MIPS
236	emulation.
237
238	<h4>Other CPU types:</h4>
239
240	Some other CPU architectures can also be partially emulated. These are not
241	working well enough yet to run guest operating systems.
242
243
244
245
246
247
248	<p><br>
249	<a name="accuracy"></a>
250	<h3>Emulation accuracy:</h3>
251
252	GXemul is an instruction-level emulator; things that would happen in
253	several steps within a real CPU are not taken into account (eg. pipe-line
254	stalls or out-of-order execution). Still, instruction-level accuracy seems
255	to be enough to be able to run complete guest operating systems inside the
256	emulator.
257
258	<p>Caches are by default not emulated. In some cases, the existance of
259	caches is "faked" to let operating systems think that they are there.
260	(There is some old code for R2000/R3000 caches, but it has probably
261	suffered from bitrot by now.)
262
263	<p>The emulator is <i>not</i> timing-accurate. It can be run in a
264	"deterministic" mode, <tt><b>-D</b></tt>. The meaning of deterministic is
265	simply that running two emulations with the same settings will result in
266	identical runs. Obviously, this requires that no user interaction is
267	taking place, and that clock speeds are fixed with the <tt><b>-I</b></tt>
268	option. (Deterministic in this case does <i>not</i> mean that the
269	emulation will be identical to some actual real-world machine.)
270
271
272
273
274
275	<p><br>
276	<a name="emulmodes"></a>
277	<h3>Which machines does GXemul emulate?</h3>
278
279	A few different machine types are emulated. The following machine types
280	are emulated well enough to run at least one "guest OS":
281
282	<p>
283	<ul>
284	<li><b><u>MIPS</u></b>
285	<ul>
286	<li><b>DECstation 5000/200</b>  ("3max")
287	<br>Serial controller (including keyboard and mouse), ethernet,
288	SCSI, and graphical framebuffers.
289	<p>
290	<li><b>Acer Pica-61</b>  (an ARC machine)
291	<br>Serial controller, "VGA" text console, and SCSI.
292	<p>
293	<li><b>NEC MobilePro 770, 780, 800, and 880</b>  (HPCmips machines)
294	<br>Framebuffer, keyboard, and a PCMCIA IDE controller.
295	<p>
296	<li><b>Cobalt</b>
297	<br>Serial controller and PCI IDE.
298	<p>
299	<li><b>Malta (evbmips)</b>
300	<br>Serial controller and PCI IDE.
301	<p>
302	<li><b>SGI O2 ("IP32")</b>
303	<br>Serial controller and ethernet.  <small>(Enough for
304	root-on-nfs, but not for disk boot.)</small>
305	</ul>
306	<p>
307	<li><b><u>ARM</u></b>
308	<ul>
309	<li><b>CATS</b>
310	<br>VGA and PCI IDE.
311	</ul>
312	</ul>
313
314	<p>There is code in GXemul for emulation of many other machine types; the
315	degree to which these work range from almost being able to run a complete
316	OS, to almost completely unsupported (perhaps just enough support to
317	output a few boot messages via serial console).
318
319	<p>In addition to emulating real machines, there is also a "test-machine".
320	A test-machine consists of one or more CPUs and a few experimental devices
321	such as:
322
323	<p>
324	<ul>
325	<li>a console I/O device (putchar() and getchar()...)
326	<li>an inter-processor communication device, for SMP experiments
327	<li>a very simple linear framebuffer device (for graphics output)
328	<li>a simple SCSI disk controller
329	<li>a simple ethernet controller
330	</ul>
331
332	<p>This mode is useful if you wish to run experimental code, but do not
333	wish to target any specific real-world machine type, for example for
334	educational purposes.
335
336	<p>You can read more about these experimental devices <a
337	href="experiments.html#expdevices">here</a>.
338
339
340
341
342
343
344
345	<p><br>
346	<a name="guestos"></a>
347	<h3>Which guest OSes are possible to run in GXemul?</h3>
348
349	This table lists the guest OSes that run well enough to be considered
350	working in the emulator. They can boot from a harddisk image and be
351	interacted with similar to a real machine.
352
353	<p>
354	<center><table border="0">
355	<tr>
356	<td width="10"></td>
357	<td align="center"><a href="20050317-example.png"><img src="20050317-example_small.png"></a></td>
358	<td width="15"></td>
359	<td><a href="http://www.netbsd.org/Ports/pmax/">NetBSD/pmax</a>
360	<br>DECstation 5000/200</td>
361	<td width="30"></td>
362	<td align="center"><a href="20041024-netbsd-arc-installed.gif"><img src="20041024-netbsd-arc-installed_small.gif"></a></td>
363	<td width="15"></td>
364	<td><a href="http://www.netbsd.org/Ports/arc/">NetBSD/arc</a>
365	<br>Acer Pica-61</td>
366
367	</tr>
368
369	<tr><td height="10"></td></tr>
370
371	<tr>
372	<td></td>
373	<td align="center"><a href="openbsd-pmax-20040710.png"><img src="openbsd-pmax-20040710_small.png"></a></td>
374	<td></td>
375	<td><a href="http://www.openbsd.org/pmax.html">OpenBSD/pmax</a>
376	<br>DECstation 5000/200</td>
377	<td></td>
378	<td align="center"><a href="20041024-openbsd-arc-installed.gif"><img src="20041024-openbsd-arc-installed_small.gif"></a></td>
379	<td></td>
380	<td><a href="http://www.openbsd.org/arc.html">OpenBSD/arc</a>
381	<br>Acer Pica-61</td>
382	</tr>
383
384	<tr><td height="10"></td></tr>
385
386	<tr>
387	<td></td>
388	<td align="center"><a href="ultrix4.5-20040706.png"><img src="ultrix4.5-20040706_small.gif"></a></td>
389	<td></td>
390	<td>Ultrix/RISC<br>DECstation 5000/200</td>
391	<td></td>
392	<td align="center"><a href="20041213-debian_4.png"><img src="20041213-debian_4_small.gif"></a></td>
393	<td></td>
394	<td><a href="http://www.debian.org/">Debian GNU/Linux</a> <super>*</super>
395	<br>DECstation 5000/200</td>
396	</tr>
397
398	<tr><td height="10"></td></tr>
399
400	<tr>
401	<td></td>
402	<td align="center"><a href="sprite-20040711.png"><img src="sprite-20040711_small.png"></a></td>
403	<td></td>
404	<td><a href="http://www.cs.berkeley.edu/projects/sprite/retrospective.html">Sprite</a>
405	<br>DECstation 5000/200</td>
406	<td></td>
407	<td align="center"><a href="20041129-redhat_mips.png"><img src="20041129-redhat_mips_small.png"></a></td>
408	<td></td>
409	<td>Redhat Linux <super>*</super>
410	<br>DECstation 5000/200</td>
411	</tr>
412
413	<tr><td height="10"></td></tr>
414
415	<tr>
416	<td></td>
417	<td align="center"><a href="20050427-netbsd-hpcmips-2.png"><img src="20050427-netbsd-hpcmips-2_small.png"></a></td>
418	<td></td>
419	<td><a href="http://www.netbsd.org/Ports/hpcmips/">NetBSD/hpcmips</a>
420	<br>NEC MobilePro 770, 780, 800, 880</td>
421	<td></td>
422	<td align="center"><a href="20050413-netbsd-cobalt.png"><img src="20050413-netbsd-cobalt_small.png"></a></td>
423	<td></td>
424	<td><a href="http://www.netbsd.org/Ports/cobalt/">NetBSD/cobalt</a>
425	<br>Cobalt</td>
426	</tr>
427
428	<tr><td height="10"></td></tr>
429
430	<tr>
431	<td></td>
432	<td align="center"><a href="20050626-netbsd-sgimips-netboot.png"><img src="20050626-netbsd-sgimips-netboot_small.png"></a></td>
433	<td></td>
434	<td><a href="http://www.netbsd.org/Ports/sgimips/">NetBSD/sgimips</a>
435	<br>SGI O2 ("IP32")</td>
436	<td></td>
437	<td align="center"><a href="20050622-netbsd-evbmips-malta.png"><img src="20050622-netbsd-evbmips-malta_small.png"></a></td>
438	<td></td>
439	<td><a href="http://www.netbsd.org/Ports/evbmips/">NetBSD/evbmips</a>
440	<br>5Kc (and 4Kc) Malta<br>evaluation boards</td>
441	<td></td>
442	</tr>
443
444	<tr><td height="10"></td></tr>
445
446	<tr>
447	<td></td>
448	<td align="center"><a href="20051007-netbsd-cats-installed.png"><img src="20051007-netbsd-cats-installed_small.png"></a></td>
449	<td></td>
450	<td><a href="http://www.netbsd.org/Ports/cats/">NetBSD/cats</a>
451	<br>CATS</td>
452	<td></td>
453	<td align="center"><a href="20051007-openbsd-cats-installed.png"><img src="20051007-openbsd-cats-installed_small.png"></a></td>
454	<td></td>
455	<td><a href="http://www.openbsd.org/cats.html">OpenBSD/cats</a>
456	<br>CATS</td>
457	<td></td>
458	</tr>
459
460	</table></center>
461
462
463	<p><br>
464
465	<super>*</super> Although Linux runs under DECstation emulation, the
466	default 2.4.27 kernel in Debian GNU/Linux does not support keyboards on
467	the 5000/200 (the specific DECstation model being emulated), so when the
468	login prompt is reached you cannot interact with the system. Kaj-Michael
469	Lang has compiled and made available a newer kernel from the current
470	mips-linux development tree. You can find it here: <a
471	href="http://home.tal.org/~milang/o2/kernels/">http://home.tal.org/~milang/o2/kernels</a>/<a
472	href="http://home.tal.org/~milang/o2/kernels/vmlinux-2.4.29-rc2-r3k-mipsel-decstation">vmlinux-2.4.29-rc2-r3k-mipsel-decstation</a>
473	This newer kernel supports keyboard input, but it does not have Debian's
474	ethernet patches, so you will not be able to use keyboard/framebuffer
475	<i>and</i> networking at the same time.
476
477
478	</body>
479	</html>