1 |
<html><head><title>Gavare's eXperimental Emulator: Introduction</title> |
2 |
<meta name="robots" content="noarchive,nofollow,noindex"></head> |
3 |
<body bgcolor="#f8f8f8" text="#000000" link="#4040f0" vlink="#404040" alink="#ff0000"> |
4 |
<table border=0 width=100% bgcolor="#d0d0d0"><tr> |
5 |
<td width=100% align=center valign=center><table border=0 width=100%><tr> |
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>Introduction</b> |
9 |
</font></td></tr></table></td></tr></table><p> |
10 |
|
11 |
<!-- |
12 |
|
13 |
$Id: intro.html,v 1.107 2007/03/08 19:04:09 debug Exp $ |
14 |
|
15 |
Copyright (C) 2003-2007 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>Introduction</h2> |
46 |
|
47 |
<p> |
48 |
<table border="0" width="99%"><tr><td valign="top" align="left"> |
49 |
<ul> |
50 |
<li><a href="#overview">Overview</a> |
51 |
<li><a href="#free">Is GXemul Free software?</a> |
52 |
<li><a href="#build">How to compile/build the emulator</a> |
53 |
<li><a href="#run">How to run the emulator</a> |
54 |
<li><a href="#cpus">Which processor architectures does GXemul emulate?</a> |
55 |
<li><a href="#hosts">Which host architectures are supported?</a> |
56 |
<li><a href="#translation">What kind of translation does GXemul use?</a> |
57 |
<li><a href="#accuracy">Emulation accuracy</a> |
58 |
<li><a href="#emulmodes">Which machines does GXemul emulate?</a> |
59 |
</ul> |
60 |
</td><td valign="center" align="center"> |
61 |
<a href="20050317-example.png"><img src="20050317-example_small.png"></a> |
62 |
<p>NetBSD/pmax 1.6.2 with X11<br>running in GXemul</td></tr></table> |
63 |
|
64 |
|
65 |
|
66 |
|
67 |
<p><br> |
68 |
<a name="overview"></a> |
69 |
<h3>Overview:</h3> |
70 |
|
71 |
GXemul is an experimental instruction-level machine emulator. Several |
72 |
emulation modes are available. In some modes, processors and surrounding |
73 |
hardware components are emulated well enough to let unmodified operating |
74 |
systems (e.g. NetBSD) run as if they were running on a real machine. |
75 |
|
76 |
<p>Devices and processors are not simulated with 100% accuracy. They are |
77 |
only ``faked'' well enough to allow guest operating systems to run without |
78 |
complaining too much. Still, the emulator could be of interest for |
79 |
academic research and experiments, such as when learning how to write |
80 |
operating system code. |
81 |
|
82 |
<p>The emulator is written in C, does not depend on third-party libraries, |
83 |
and should compile and run on most 64-bit and 32-bit Unix-like systems. |
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, Dreamcast |
99 |
emulation, or when booting from generic ISO9660 CDROM images if the |
100 |
kernel is included in the image as a plain file.) |
101 |
|
102 |
<p>Thanks to (in no specific order) Joachim Buss, Olivier Houchard, Juli |
103 |
Mallett, Juan Romero Pardines, Alec Voropay, Göran Weinholt, Alexander |
104 |
Yurchenko, and everyone else who has provided me with feedback. |
105 |
|
106 |
|
107 |
|
108 |
|
109 |
|
110 |
|
111 |
|
112 |
<p><br> |
113 |
<a name="free"></a> |
114 |
<h3>Is GXemul Free software?</h3> |
115 |
|
116 |
Yes. I have released GXemul under a Free license. The code in GXemul is |
117 |
Copyrighted software, it is <i>not</i> public domain. (If this is |
118 |
confusing to you, you might want to read up on the definitions of the |
119 |
four freedoms associated with Free software, <a |
120 |
href="http://www.gnu.org/philosophy/free-sw.html">http://www.gnu.org/philosophy/free-sw.html</a>.) |
121 |
|
122 |
<p>The code I have written is released under a 3-clause BSD-style license |
123 |
(or "revised BSD-style" if one wants to use <a |
124 |
href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>). Apart from |
125 |
the code I have written, some files are copied from other sources such as |
126 |
NetBSD, for example header files containing symbolic names of bitfields in |
127 |
device registers. They are also covered by similar licenses, but with some |
128 |
additional clauses. The main point, however, is that the licenses require |
129 |
that the original Copyright and license terms are included when you make a |
130 |
copy or modification. |
131 |
|
132 |
<p>If you plan to redistribute GXemul <i>without</i> supplying the source |
133 |
code, then you need to comply with each individual source file some other |
134 |
way, for example by writing additional documentation containing copyright |
135 |
notes. I have not done this, since I do not plan on making distributions |
136 |
without source code. You need to check all individual files for details. |
137 |
The "easiest way out" if you plan to redistribute code from GXemul is, of |
138 |
course, to let it remain open source and simply supply the source code. |
139 |
|
140 |
<p>In case you want to reuse parts of GXemul, but you need to do that |
141 |
under a different license (e.g. the GPL), then contact me and I might |
142 |
re-license/dual-license files on a case-by-case basis. |
143 |
|
144 |
|
145 |
|
146 |
|
147 |
|
148 |
<p><br> |
149 |
<a name="build"></a> |
150 |
<h3>How to compile/build the emulator:</h3> |
151 |
|
152 |
Uncompress the .tar.gz distribution file, and run |
153 |
<pre> |
154 |
$ <b>./configure</b> |
155 |
$ <b>make</b> |
156 |
</pre> |
157 |
|
158 |
<p>This should work on most Unix-like systems. GXemul does not require any |
159 |
specific libraries to build, however, if you build on a system which does |
160 |
not have X11 libraries installed, some functionality will be lost. |
161 |
|
162 |
<p>The emulator's performance is highly dependent on both runtime settings |
163 |
and on compiler settings, so you might want to experiment with different |
164 |
CC and CFLAGS environment variable values. For example, on an AMD Athlon |
165 |
host, you might want to try setting <tt>CFLAGS</tt> to <tt>-march=athlon</tt> |
166 |
before running <tt>configure</tt>. |
167 |
|
168 |
|
169 |
|
170 |
|
171 |
|
172 |
|
173 |
|
174 |
<p><br> |
175 |
<a name="run"></a> |
176 |
<h3>How to run the emulator:</h3> |
177 |
|
178 |
Once you have built GXemul, running it should be rather straight-forward. |
179 |
Running <tt><b>gxemul</b></tt> without arguments (or with the |
180 |
<b><tt>-h</tt></b> or <b><tt>-H</tt></b> command line options) will |
181 |
display a help message. |
182 |
|
183 |
<p> |
184 |
To get some ideas about what is possible to run in the emulator, please |
185 |
read the section about <a href="guestoses.html">installing "guest" |
186 |
operating systems</a>. If you are interested in using the emulator to |
187 |
develop code on your own, then you should also read the section about |
188 |
<a href="experiments.html#hello">Hello World</a>. |
189 |
|
190 |
<p> |
191 |
To exit the emulator, type CTRL-C to enter the |
192 |
single-step debugger, and then type <tt><b>quit</b></tt>. |
193 |
|
194 |
<p> |
195 |
If you are starting an emulation by entering settings directly on the |
196 |
command line, and you are not using the <tt><b>-x</b></tt> option, then all |
197 |
terminal input and output will go to the main controlling terminal. |
198 |
CTRL-C is used to break into the debugger, so in order to send CTRL-C to |
199 |
the running (emulated) program, you may use CTRL-B. |
200 |
(This should be a reasonable compromise to allow the emulator to be usable |
201 |
even on systems without X Windows.) |
202 |
|
203 |
<p> |
204 |
There is no way to send an actual CTRL-B to the emulated program, when |
205 |
typing in the main controlling terminal window. The solution is to either |
206 |
use <a href="configfiles.html">configuration files</a>, or use |
207 |
<tt><b>-x</b></tt>. Both these solutions cause new xterms to be opened for |
208 |
each emulated serial port that is written to. CTRL-B and CTRL-C both have |
209 |
their original meaning in those xterm windows. |
210 |
|
211 |
|
212 |
|
213 |
|
214 |
|
215 |
<p><br> |
216 |
<a name="cpus"></a> |
217 |
<h3>Which processor architectures does GXemul emulate?</h3> |
218 |
|
219 |
The architectures that are emulated well enough to let at least one |
220 |
guest operating system run (per architecture) are ARM, MIPS, PowerPC, |
221 |
and SuperH. |
222 |
|
223 |
<p>Please read the page about <a href="guestoses.html">guest operating |
224 |
systems</a> for more information about the machines and operating systems |
225 |
that can be considered "working" in the emulator. |
226 |
|
227 |
|
228 |
|
229 |
|
230 |
|
231 |
|
232 |
<p><br> |
233 |
<a name="hosts"></a> |
234 |
<h3>Which host architectures are supported?</h3> |
235 |
|
236 |
GXemul should compile and run on any modern host architecture (64-bit or |
237 |
32-bit word-length). |
238 |
|
239 |
<p>Note: The dynamic translation engine does <i>not</i> require backends |
240 |
for native code generation to be written for each individual host |
241 |
architecture; the "intermediate representation" that the dyntrans system |
242 |
uses can be executed on any host architecture. |
243 |
|
244 |
|
245 |
|
246 |
|
247 |
|
248 |
<p><br> |
249 |
<a name="translation"></a> |
250 |
<h3>What kind of translation does GXemul use?</h3> |
251 |
|
252 |
<b>Static vs. dynamic:</b> |
253 |
|
254 |
<p>In order to support guest operating systems, which can overwrite old |
255 |
code pages in memory with new code, it is necessary to translate code |
256 |
dynamically. It is not possible to do a "one-pass" (static) translation. |
257 |
Self-modifying code and Just-in-Time compilers running inside |
258 |
the emulator are other things that would not work with a static |
259 |
translator. GXemul is a dynamic translator. However, it does not |
260 |
necessarily translate into native code, like many other emulators. |
261 |
|
262 |
<p><b>"Runnable" Intermediate Representation:</b> |
263 |
|
264 |
<p>Dynamic translators usually translate from the emulated architecture |
265 |
(e.g. MIPS) into a kind of <i>intermediate representation</i> (IR), and then |
266 |
to native code (e.g. AMD64 or x86 code). Since one of my main goals for |
267 |
GXemul is to keep everything as portable as possible, I have tried to make |
268 |
sure that the IR is something which can be executed regardless of whether |
269 |
the final step (translation from IR to native code) has been implemented |
270 |
or not. |
271 |
|
272 |
<p>The IR in GXemul consists of arrays of pointers to functions, and a few |
273 |
arguments which are passed along to those functions. The functions are |
274 |
implemented in either manually hand-coded C, or automatically generated C. |
275 |
In any case, this is all statically linked into the GXemul binary at link |
276 |
time. |
277 |
|
278 |
<p>Here is a simplified diagram of how these arrays work. |
279 |
|
280 |
<p><center><img src="simplified_dyntrans.png"></center> |
281 |
|
282 |
<p>There is one instruction call slot for every possible program counter |
283 |
location. In the MIPS case, instruction words are 32 bits in length, |
284 |
and pages are (usually) 4 KB large, resulting in 1024 instruction call |
285 |
slots. After the last of these instruction calls, there is an additional |
286 |
call to a special "end of page" function (which doesn't count as an executed |
287 |
instruction). This function switches to the first instruction |
288 |
on the next virtual page (which might cause exceptions, etc). |
289 |
|
290 |
<p>The complexity of individual instructions vary. A simple example of |
291 |
what an instruction can look like is the MIPS <tt>addiu</tt> instruction: |
292 |
<pre> |
293 |
X(addiu) |
294 |
{ |
295 |
reg(ic->arg[1]) = (int32_t) |
296 |
((int32_t)reg(ic->arg[0]) + (int32_t)ic->arg[2]); |
297 |
} |
298 |
</pre> |
299 |
|
300 |
<p>It stores the result of a 32-bit addition of the register at arg[0] |
301 |
with the immediate value arg[2] (treating both as signed 32-bit |
302 |
integers) into register arg[1]. If the emulated CPU is a 64-bit CPU, |
303 |
then this will store a correctly sign-extended value into arg[1]. |
304 |
If it is a 32-bit CPU, then only the lowest 32 bits will be stored, |
305 |
and the high part ignored. <tt>X(addiu)</tt> is expanded to |
306 |
<tt>mips_instr_addiu</tt> in the 64-bit case, and <tt>mips32_instr_addiu</tt> |
307 |
in the 32-bit case. Both are compiled into the GXemul executable; no code |
308 |
is created during run-time. |
309 |
|
310 |
<p>Here are examples of what the <tt>addiu</tt> instruction actually |
311 |
looks like when it is compiled, on various host architectures: |
312 |
|
313 |
<p><center><table border="0"> |
314 |
<tr><td><b>GCC 4.0.1 on Alpha:</b></td> |
315 |
<td width="35"></td><td></td> |
316 |
<tr> |
317 |
<td valign="top"> |
318 |
<pre>mips_instr_addiu: |
319 |
ldq t1,8(a1) |
320 |
ldq t2,24(a1) |
321 |
ldq t3,16(a1) |
322 |
ldq t0,0(t1) |
323 |
addl t0,t2,t0 |
324 |
stq t0,0(t3) |
325 |
ret</pre> |
326 |
</td> |
327 |
<td></td> |
328 |
<td valign="top"> |
329 |
<pre>mips32_instr_addiu: |
330 |
ldq t2,8(a1) |
331 |
ldq t0,24(a1) |
332 |
ldq t3,16(a1) |
333 |
ldl t1,0(t2) |
334 |
addq t0,t1,t0 |
335 |
stl t0,0(t3) |
336 |
ret</pre> |
337 |
</td> |
338 |
</tr> |
339 |
|
340 |
<tr><td><b><br>GCC 3.4.4 on AMD64:</b></td> |
341 |
<tr> |
342 |
<td valign="top"> |
343 |
<pre>mips_instr_addiu: |
344 |
mov 0x8(%rsi),%rdx |
345 |
mov 0x18(%rsi),%rax |
346 |
mov 0x10(%rsi),%rcx |
347 |
add (%rdx),%eax |
348 |
cltq |
349 |
mov %rax,(%rcx) |
350 |
retq</pre> |
351 |
</td> |
352 |
<td></td> |
353 |
<td valign="top"> |
354 |
<pre>mips32_instr_addiu: |
355 |
mov 0x8(%rsi),%rcx |
356 |
mov 0x10(%rsi),%rdx |
357 |
mov (%rcx),%eax |
358 |
add 0x18(%rsi),%eax |
359 |
mov %eax,(%rdx) |
360 |
retq</pre> |
361 |
</td> |
362 |
</tr> |
363 |
|
364 |
<tr><td><b><br>GCC 4.0.1 on i386:</b></td> |
365 |
<tr> |
366 |
<td valign="top"> |
367 |
<pre>mips_instr_addiu: |
368 |
mov 0x8(%esp),%eax |
369 |
mov 0x8(%eax),%ecx |
370 |
mov 0x4(%eax),%edx |
371 |
mov 0xc(%eax),%eax |
372 |
add (%edx),%eax |
373 |
mov %eax,(%ecx) |
374 |
cltd |
375 |
mov %edx,0x4(%ecx) |
376 |
ret</pre> |
377 |
</td> |
378 |
<td></td> |
379 |
<td valign="top"> |
380 |
<pre>mips32_instr_addiu: |
381 |
mov 0x8(%esp),%eax |
382 |
mov 0x8(%eax),%ecx |
383 |
mov 0x4(%eax),%edx |
384 |
mov 0xc(%eax),%eax |
385 |
add (%edx),%eax |
386 |
mov %eax,(%ecx) |
387 |
ret</pre> |
388 |
</td> |
389 |
</tr> |
390 |
</table></center> |
391 |
|
392 |
<p>On 64-bit hosts, there is not much difference, but on 32-bit hosts (and |
393 |
to some extent on AMD64), the difference is enough to make it worthwhile. |
394 |
|
395 |
|
396 |
<p><b>Performance:</b> |
397 |
|
398 |
<p>The performance of using this kind of runnable IR is obviously lower |
399 |
than what can be achieved by emulators using native code generation, but |
400 |
can be significantly higher than using a naive fetch-decode-execute |
401 |
interpretation loop. In my opinion, using a runnable IR is an interesting |
402 |
compromise. |
403 |
|
404 |
<p>The overhead per emulated instruction is usually around or below |
405 |
approximately 10 host instructions. This is very much dependent on your |
406 |
host architecture and what compiler and compiler switches you are using. |
407 |
Added to this instruction count is (of course) also the C code used to |
408 |
implement each specific instruction. |
409 |
|
410 |
<p><b>Instruction Combinations:</b> |
411 |
|
412 |
<p>Short, common instruction sequences can sometimes be replaced by a |
413 |
"compound" instruction. An example could be a compare instruction followed |
414 |
by a conditional branch instruction. The advantages of instruction |
415 |
combinations are that |
416 |
<ul> |
417 |
<li>the amortized overhead per instruction is slightly reduced, and |
418 |
<p> |
419 |
<li>the host's compiler can make a good job at optimizing the common |
420 |
instruction sequence. |
421 |
</ul> |
422 |
|
423 |
<p>The special cases where instruction combinations give the most gain |
424 |
are in the cores of string/memory manipulation functions such as |
425 |
<tt>memset()</tt> or <tt>strlen()</tt>. The core loop can then (at least |
426 |
to some extent) be replaced by a native call to the equivalent function. |
427 |
|
428 |
<p>The implementations of compound instructions still keep track of the |
429 |
number of executed instructions, etc. When single-stepping, these |
430 |
translations are invalidated, and replaced by normal instruction calls |
431 |
(one per emulated instruction). |
432 |
|
433 |
<p><b>Native Code Back-ends:</b> |
434 |
|
435 |
<p>In theory, it will be possible to implement native code generation, |
436 |
similar to what is used in high-performance emulators such as QEMU, |
437 |
as long as that generated code abides to the C ABI on the host. |
438 |
|
439 |
<p>However, since I wanted to make sure that GXemul works without such |
440 |
native code back-ends, there are no implemented backends in this release. |
441 |
|
442 |
<p>(There is a place-holder in the source code for native code generation, |
443 |
which can be used for experiments, but it does not contain any working |
444 |
code at the moment.) |
445 |
|
446 |
|
447 |
|
448 |
|
449 |
|
450 |
|
451 |
<p><br> |
452 |
<a name="accuracy"></a> |
453 |
<h3>Emulation accuracy:</h3> |
454 |
|
455 |
GXemul is an instruction-level emulator; things that would happen in |
456 |
several steps within a real CPU are not taken into account (e.g. pipe-line |
457 |
stalls or out-of-order execution). Still, instruction-level accuracy seems |
458 |
to be enough to be able to run complete guest operating systems inside the |
459 |
emulator. |
460 |
|
461 |
<p>The existance of instruction and data caches is "faked" to let |
462 |
operating systems think that they are there, but for all practical |
463 |
purposes, these caches are non-working. |
464 |
|
465 |
<p>The emulator is in general <i>not</i> timing-accurate, neither at the |
466 |
instruction level nor on any higher level. An attempt is made to let |
467 |
emulated clocks run at the same speed as the host (i.e. an emulated timer |
468 |
running at 100 Hz will interrupt around 100 times per real second), but |
469 |
since the host speed may vary, e.g. because of other running processes, |
470 |
there is no guarantee as to how many instructions will be executed in |
471 |
each of these 100 Hz cycles. |
472 |
|
473 |
<p>If the host is very slow, the emulated clocks might even lag behind |
474 |
the real-world clock. |
475 |
|
476 |
|
477 |
|
478 |
|
479 |
|
480 |
|
481 |
<p><br> |
482 |
<a name="emulmodes"></a> |
483 |
<h3>Which machines does GXemul emulate?</h3> |
484 |
|
485 |
A few different machine types are emulated. The following machine types |
486 |
are emulated well enough to run at least one "guest OS": |
487 |
|
488 |
<p> |
489 |
<ul> |
490 |
<li><b><u>ARM</u></b> |
491 |
<ul> |
492 |
<li><b>CATS</b> (<a href="guestoses.html#netbsdcatsinstall">NetBSD/cats</a>, |
493 |
<a href="guestoses.html#openbsdcatsinstall">OpenBSD/cats</a>) |
494 |
<li><b>IQ80321</b> (<a href="guestoses.html#netbsdevbarminstall">NetBSD/evbarm</a>) |
495 |
<li><b>NetWinder</b> (<a href="guestoses.html#netbsdnetwinderinstall">NetBSD/netwinder</a>) |
496 |
</ul> |
497 |
<p> |
498 |
<li><b><u>MIPS</u></b> |
499 |
<ul> |
500 |
<li><b>DECstation 5000/200</b> (<a href="guestoses.html#netbsdpmaxinstall">NetBSD/pmax</a>, |
501 |
<a href="guestoses.html#openbsdpmaxinstall">OpenBSD/pmax</a>, |
502 |
<a href="guestoses.html#ultrixinstall">Ultrix</a>, |
503 |
<a href="guestoses.html#declinux">Linux/DECstation</a>, |
504 |
<a href="guestoses.html#sprite">Sprite</a>) |
505 |
<li><b>Acer Pica-61</b> (<a href="guestoses.html#netbsdarcinstall">NetBSD/arc</a>) |
506 |
<li><b>NEC MobilePro 770, 780, 800, 880</b> (<a href="guestoses.html#netbsdhpcmipsinstall">NetBSD/hpcmips</a>) |
507 |
<li><b>Cobalt</b> (<a href="guestoses.html#netbsdcobaltinstall">NetBSD/cobalt</a>) |
508 |
<li><b>Malta</b> (<a href="guestoses.html#netbsdevbmipsinstall">NetBSD/evbmips</a>, Linux/Malta <font color="#0000e0">(<super>*1</super>)</font>) |
509 |
<li><b>Algorithmics P5064</b> (<a href="guestoses.html#netbsdalgorinstall">NetBSD/algor</a>) |
510 |
<li><b>SGI O2 (aka IP32)</b> <font color="#0000e0">(<super>*2</super>)</font> |
511 |
(<a href="guestoses.html#netbsdsgimips">NetBSD/sgi</a>) |
512 |
</ul> |
513 |
<p> |
514 |
<li><b><u>PowerPC</u></b> |
515 |
<ul> |
516 |
<li><b>IBM 6050/6070 (PReP, PowerPC Reference Platform)</b> (<a href="guestoses.html#netbsdprepinstall">NetBSD/prep</a>) |
517 |
<li><b>MacPPC (generic "G4" Macintosh)</b> (<a href="guestoses.html#netbsdmacppcinstall">NetBSD/macppc</a>) |
518 |
</ul> |
519 |
<p> |
520 |
<li><b><u>SuperH</u></b> |
521 |
<ul> |
522 |
<li><b>Sega Dreamcast</b> (<a href="dreamcast.html#netbsd_generic_md">NetBSD/dreamcast</a>, <a href="dreamcast.html#linux_live_cd">Linux/dreamcast</a>) |
523 |
</ul> |
524 |
</ul> |
525 |
|
526 |
<p> |
527 |
<small><font color="#0000e0">(<super>*1</super>)</font> = |
528 |
Linux/Malta may be run as a guest OS, however I have not yet found any stable |
529 |
URL to pre-compiled Linux/Malta kernels. Thus, Linux/Malta emulation is not |
530 |
tested for every release of the emulator; sometimes it works, sometimes |
531 |
it doesn't.</small> |
532 |
|
533 |
<br><small><font color="#0000e0">(<super>*2</super>)</font> = |
534 |
SGI O2 emulation is enough for root-on-nfs, but not for disk boot.</small> |
535 |
|
536 |
|
537 |
<p>There is code in GXemul for emulation of many other machine types; the |
538 |
degree to which these work range from almost being able to run a complete |
539 |
OS, to almost completely unsupported (perhaps just enough support to |
540 |
output a few boot messages via serial console). |
541 |
|
542 |
<p>In addition to emulating real machines, there is also a "test-machine". |
543 |
A test-machine consists of one or more CPUs and a few experimental devices |
544 |
such as: |
545 |
|
546 |
<p> |
547 |
<ul> |
548 |
<li>a console I/O device (putchar() and getchar()...) |
549 |
<li>an inter-processor communication device, for SMP experiments |
550 |
<li>a very simple linear framebuffer device (for graphics output) |
551 |
<li>a simple disk controller |
552 |
<li>a simple ethernet controller |
553 |
<li>a real-time clock device |
554 |
</ul> |
555 |
|
556 |
<p>This mode is useful if you wish to run experimental code, but do not |
557 |
wish to target any specific real-world machine type, for example for |
558 |
educational purposes. |
559 |
|
560 |
<p>You can read more about these experimental devices <a |
561 |
href="experiments.html#expdevices">here</a>. |
562 |
|
563 |
|
564 |
|
565 |
|
566 |
|
567 |
|
568 |
</body> |
569 |
</html> |