/[gxemul]/trunk/doc/intro.html
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
ViewVC logotype

Contents of /trunk/doc/intro.html

Parent Directory Parent Directory | Revision Log Revision Log


Revision 22 - (show annotations)
Mon Oct 8 16:19:37 2007 UTC (12 years, 4 months ago) by dpavlin
File MIME type: text/html
File size: 13060 byte(s)
++ trunk/HISTORY	(local)
$Id: HISTORY,v 1.1121 2006/02/18 21:03:08 debug Exp $
20051126	Cobalt and PReP now work with the 21143 NIC.
		Continuing on Alpha dyntrans things.
		Fixing some more left-shift-by-24 to unsigned.
20051127	Working on OpenFirmware emulation; major cleanup/redesign.
		Progress on MacPPC emulation: NetBSD detects two CPUs (when
		running with -n 2), framebuffer output (for text) works.
		Adding quick-hack Bandit PCI controller and "gc" interrupt
		controller for MacPPC.
20051128	Changing from a Bandit to a Uni-North controller for macppc.
		Continuing on OpenFirmware and MacPPC emulation in general
		(obio controller, and wdc attached to the obio seems to work).
20051129	More work on MacPPC emulation (adding a dummy ADB controller).
		Continuing the PCI bus cleanup (endianness and tag composition)
		and rewriting all PCI controllers' access functions.
20051130	Various minor PPC dyntrans optimizations.
		Manually inlining some parts of the framebuffer redraw routine.
		Slowly beginning the conversion of the old MIPS emulation into
		dyntrans (but this will take quite some time to get right).
		Generalizing quick_pc_to_pointers.
20051201	Documentation update (David Muse has made available a kernel
		which simplifies Debian/DECstation installation).
		Continuing on the ADB bus controller.
20051202	Beginning a rewrite of the Zilog serial controller (dev_zs).
20051203	Continuing on the zs rewrite (now called dev_z8530); conversion
		to devinit style.
		Reworking some of the input-only vs output-only vs input-output
		details of src/console.c, better warning messages, and adding
		a debug dump.
		Removing the concept of "device state"; it wasn't really used.
		Changing some debug output (-vv should now be used to show all
		details about devices and busses; not shown during normal
		startup anymore).
		Beginning on some SPARC instruction disassembly support.
20051204	Minor PPC updates (WALNUT skeleton stuff).
		Continuing on the MIPS dyntrans rewrite.
		More progress on the ADB controller (a keyboard is "detected"
		by NetBSD and OpenBSD).
		Downgrading OpenBSD/arc as a guest OS from "working" to
		"almost working" in the documentation.
		Progress on Algor emulation ("v3" PCI controller).
20051205	Minor updates.
20051207	Sorting devices according to address; this reduces complexity
		of device lookups from O(n) to O(log n) in memory_rw (but no
		real performance increase (yet) in experiments).
20051210	Beginning the work on native dyntrans backends (by making a
		simple skeleton; so far only for Alpha hosts).
20051211	Some very minor SPARC updates.
20051215	Fixing a bug in the MIPS mul (note: not mult) instruction,
		so it also works with non-64-bit emulation. (Thanks to Alec
		Voropay for noticing the problem.)
20051216	More work on the fake/empty/simple/skeleton/whatever backend;
		performance doesn't increase, so this isn't really worth it,
		but it was probably worth it to prepare for a real backend
		later.
20051219	More instr call statistics gathering and analysis stuff.
20051220	Another fix for MIPS 'mul'. Also converting mul and {d,}cl{o,z}
		to dyntrans.
		memory_ppc.c syntax error fix (noticed by Peter Valchev).
		Beginning to move out machines from src/machine.c into
		individual files in src/machines (in a way similar to the
		autodev system for devices).
20051222	Updating the documentation regarding NetBSD/pmax 3.0.
20051223	- " - NetBSD/cats 3.0.
20051225	- " - NetBSD/hpcmips 3.0.
20051226	Continuing on the machine registry redesign.
		Adding support for ARM rrx (33-bit rotate).
		Fixing some signed/unsigned issues (exposed by gcc -W).
20051227	Fixing the bug which prevented a NetBSD/prep 3.0 install kernel
		from starting (triggered when an mtmsr was the last instruction
		on a page). Unfortunately not enough to get the kernel to run
		as well as the 2.1 kernels did.
20051230	Some dyntrans refactoring.
20051231	Continuing on the machine registry redesign.
20060101-10	Continuing... moving more machines. Moving MD interrupt stuff
		from machine.c into a new src/machines/interrupts.c.
20060114	Adding various mvmeppc machine skeletons.
20060115	Continuing on mvme* stuff. NetBSD/mvmeppc prints boot messages
		(for MVME1600) and reaches the root device prompt, but no
		specific hardware devices are emulated yet.
20060116	Minor updates to the mvme1600 emulation mode; the Eagle PCI bus
		seems to work without much modification, and a 21143 can be
		detected, interrupts might work (but untested so far).
		Adding a fake MK48Txx (mkclock) device, for NetBSD/mvmeppc.
20060121	Adding an aux control register for ARM. (A BIG thank you to
		Olivier Houchard for tracking down this bug.)
20060122	Adding more ARM instructions (smulXY), and dev_iq80321_7seg.
20060124	Adding disassembly of more ARM instructions (mia*, mra/mar),
		and some semi-bogus XScale and i80321 registers.
20060201-02	Various minor updates. Moving the last machines out of
		machine.c.
20060204	Adding a -c command line option, for running debugger commands
		before the simulation starts, but after all files have been
		loaded.
		Minor iq80321-related updates.
20060209	Minor hacks (DEVINIT macro, etc).
		Preparing for the generalization of the 64-bit dyntrans address
		translation subsystem.
20060216	Adding ARM ldrd (double-register load).
20060217	Continuing on various ARM-related stuff.
20060218	More progress on the ATA/wdc emulation for NetBSD/iq80321.
		NetBSD/evbarm can now be installed :-)  Updating the docs, etc.
		Continuing on Algor emulation.

==============  RELEASE 0.3.8  ==============


1 <html><head><title>Gavare's eXperimental Emulator:&nbsp;&nbsp;&nbsp;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 1.73 2006/02/18 14:02:19 debug Exp $
14
15 Copyright (C) 2003-2006 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>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="#accuracy">Emulation accuracy</a>
56 <li><a href="#emulmodes">Which machines does GXemul emulate?</a>
57 </ul>
58 </td><td valign="center" align="center">
59 <a href="20050317-example.png"><img src="20050317-example_small.png"></a>
60 <p>NetBSD/pmax 1.6.2 with X11<br>running in GXemul</td></tr></table>
61
62
63
64
65 <p><br>
66 <a name="overview"></a>
67 <h3>Overview:</h3>
68
69 GXemul is an experimental instruction-level machine emulator. Several
70 emulation modes are available. In some modes, processors and surrounding
71 hardware components are emulated well enough to let unmodified operating
72 systems (e.g. NetBSD) run as if they were running on a real machine.
73
74 <p>The processor architecture best emulated by GXemul is MIPS, but other
75 architectures such as ARM and PowerPC are also partially emulated.
76
77 <p>Devices and CPUs are not simulated with 100% accuracy. They are only
78 ``faked'' well enough to allow guest operating systems run without
79 complaining too much. Still, the emulator could be of interest for
80 academic research and experiments, such as when learning how to write
81 operating system code.
82
83 <p>The emulator is written in C, does not depend on third-party libraries,
84 and should compile and run on most 64-bit and 32-bit Unix-like systems.
85
86 <p>The emulator contains code which tries to emulate the workings of CPUs
87 and surrounding hardware found in real machines, but it does not contain
88 any ROM code. You will need some form of program (in binary form) to run
89 in the emulator. For many emulation modes, PROM calls are handled by the
90 emulator itself, so you do not need to use any ROM image at all.
91
92 <p>You can use pre-compiled kernels (for example NetBSD kernels, or
93 Linux), or other programs that are in binary format, and in some cases
94 even actual ROM images. A couple of different file formats are supported
95 (ELF, a.out, ECOFF, SREC, and raw binaries).
96
97 <p>If you do not have a kernel as a separate file, but you have a bootable
98 disk image, then it is sometimes possible to boot directly from that
99 image. (This works for example with DECstation emulation, or when booting
100 from ISO9660 CDROM images.)
101
102
103
104
105
106
107
108
109 <p><br>
110 <a name="free"></a>
111 <h3>Is GXemul Free software?</h3>
112
113 Yes. I have released GXemul under a Free license. The code in GXemul is
114 Copyrighted software, it is <i>not</i> public domain. (If this is
115 confusing to you, you might want to read up on the definitions of the
116 four freedoms associated with Free software, <a
117 href="http://www.gnu.org/philosophy/free-sw.html">http://www.gnu.org/philosophy/free-sw.html</a>.)
118
119 <p>The code I have written is released under a 3-clause BSD-style license
120 (or "revised BSD-style" if one wants to use <a
121 href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>). Apart from
122 the code I have written, some files are copied from other sources such as
123 NetBSD, for example header files containing symbolic names of bitfields in
124 device registers. They are also covered by similar licenses, but with some
125 additional clauses. The main point, however, is that the licenses require
126 that the original Copyright and license terms are included when you make a
127 copy or modification.
128
129 <p>If you plan to redistribute GXemul <i>without</i> supplying the source
130 code, then you need to comply with each individual source file some other
131 way, for example by writing additional documentation containing copyright
132 notes. I have not done this, since I do not plan on making distributions
133 without source code. You need to check all individual files for details.
134 The "easiest way out" if you plan to redistribute code from GXemul is, of
135 course, to let it remain open source and simply supply the source code.
136
137 <p>In case you want to reuse parts of GXemul, but you need to do that
138 under a different license (e.g. the GPL), then contact me and I might
139 re-license/dual-license files on a case-by-case basis.
140
141
142
143
144
145 <p><br>
146 <a name="build"></a>
147 <h3>How to compile/build the emulator:</h3>
148
149 Uncompress the .tar.gz distribution file, and run
150 <pre>
151 $ <b>./configure</b>
152 $ <b>make</b>
153 </pre>
154
155 <p>This should work on most Unix-like systems. GXemul does not require any
156 specific libraries to build, however, if you build on a system which does
157 not have X11 libraries installed, some functionality will be lost.
158
159 <p>The emulator's performance is highly dependent on both runtime settings
160 and on compiler settings, so you might want to experiment with different
161 CC and CFLAGS environment variable values. For example, on an AMD Athlon
162 host, you might want to try setting <tt>CFLAGS</tt> to <tt>-march=athlon
163 -O3</tt> before running <tt>configure</tt>.
164
165
166
167
168
169
170
171 <p><br>
172 <a name="run"></a>
173 <h3>How to run the emulator:</h3>
174
175 Once you have built GXemul, running it should be rather straight-forward.
176 Running <tt><b>gxemul</b></tt> without arguments (or with the
177 <b><tt>-h</tt></b> or <b><tt>-H</tt></b> command line options) will
178 display a help message.
179
180 <p>
181 To get some ideas about what is possible to run in the emulator, please
182 read the section about <a href="guestoses.html">installing "guest"
183 operating systems</a>. If you are interested in using the emulator to
184 develop code on your own, then you should also read the section about
185 <a href="experiments.html#hello">Hello World</a>.
186
187 <p>
188 To exit the emulator, type CTRL-C to enter the
189 single-step debugger, and then type <tt><b>quit</b></tt>.
190
191 <p>
192 If you are starting an emulation by entering settings directly on the
193 command line, and you are not using the <tt><b>-x</b></tt> option, then all
194 terminal input and output will go to the main controlling terminal.
195 CTRL-C is used to break into the debugger, so in order to send CTRL-C to
196 the running (emulated) program, you may use CTRL-B.
197 (This should be a reasonable compromise to allow the emulator to be usable
198 even on systems without X Windows.)
199
200 <p>
201 There is no way to send an actual CTRL-B to the emulated program, when
202 typing in the main controlling terminal window. The solution is to either
203 use <a href="configfiles.html">configuration files</a>, or use
204 <tt><b>-x</b></tt>. Both these solutions cause new xterms to be opened for
205 each emulated serial port that is written to. CTRL-B and CTRL-C both have
206 their original meaning in those xterm windows.
207
208
209
210
211
212 <p><br>
213 <a name="cpus"></a>
214 <h3>Which processor architectures does GXemul emulate?</h3>
215
216 <h4>MIPS:</h4>
217
218 Emulation of R4000, which is a 64-bit CPU, was my initial goal.
219 R2000/R3000-like CPUs (32-bit), R1x000, and generic MIPS32/MIPS64-style
220 CPUs are also emulated, and are hopefully almost as stable as the R4000
221 emulation. Several guest operating systems for MIPS can run inside
222 the emulator.
223
224 <p>(For MIPS emulation, I have written an experimental dynamic binary
225 translation subsystem, for Alpha and i386 hosts. This gives higher total
226 performance than interpreting one instruction at a time and executing it.
227 If you wish to disable bintrans, add <b>-B</b> to the command line.)
228
229 <h4>ARM:</h4>
230
231 ARM emulation is good enough to run NetBSD/cats, OpenBSD/cats, and
232 NetBSD/evbarm, but it is not as tested or fine-tuned as the MIPS emulation
233 mode.
234
235 <h4>PowerPC:</h4>
236
237 PowerPC emulation is still in its beginning stages, but good enough
238 to run NetBSD/prep 2.1.
239
240 <p>Non-MIPS emulation modes use dynamic translation, but not recompilation
241 into native code. This makes it possible to run on any host platform.
242
243
244
245
246
247 <p><br>
248 <a name="accuracy"></a>
249 <h3>Emulation accuracy:</h3>
250
251 GXemul is an instruction-level emulator; things that would happen in
252 several steps within a real CPU are not taken into account (eg. pipe-line
253 stalls or out-of-order execution). Still, instruction-level accuracy seems
254 to be enough to be able to run complete guest operating systems inside the
255 emulator.
256
257 <p>Caches are by default not emulated. In some cases, the existance of
258 caches is "faked" to let operating systems think that they are there.
259 (There is some old code for R2000/R3000 caches, but it has probably
260 suffered from bitrot by now.)
261
262 <p>The emulator is <i>not</i> timing-accurate. It can be run in a
263 "deterministic" mode, <tt><b>-D</b></tt>. The meaning of deterministic is
264 simply that running two emulations with the same settings will result in
265 identical runs. Obviously, this requires that no user interaction is
266 taking place, and that clock speeds are fixed with the <tt><b>-I</b></tt>
267 option. (Deterministic in this case does <i>not</i> mean that the
268 emulation will be identical to some actual real-world machine.)
269
270 <p><font color="#ff0000">(Oops/TODO: User interaction means <i>both</i>
271 input to the emulated program/OS, and interacting with the emulator
272 itself. Breaking into the debugger and then continuing execution may
273 affect when/how interrupts occur.)</font>
274
275
276
277
278
279
280 <p><br>
281 <a name="emulmodes"></a>
282 <h3>Which machines does GXemul emulate?</h3>
283
284 A few different machine types are emulated. The following machine types
285 are emulated well enough to run at least one "guest OS":
286
287 <p>
288 <ul>
289 <li><b><u>MIPS</u></b>
290 <ul>
291 <li><b>DECstation 5000/200</b>&nbsp;&nbsp;("3max")
292 <li><b>Acer Pica-61</b>&nbsp;&nbsp;(an ARC machine)
293 <li><b>NEC MobilePro 770, 780, 800, and 880</b>&nbsp;&nbsp;(HPCmips machines)
294 <li><b>Cobalt</b>
295 <li><b>Malta</b> (evbmips)
296 <li><b>SGI O2 ("IP32")</b> <font color="#0000e0">(<super>*</super>)</font>
297 </ul>
298 <p>
299 <li><b><u>ARM</u></b>
300 <ul>
301 <li><b>CATS</b>
302 <li><b>IQ80321</b> (evbarm)
303 </ul>
304 <p>
305 <li><b><u>PowerPC</u></b>
306 <ul>
307 <li><b>PReP (PowerPC Reference Platform)</b>
308 </ul>
309 </ul>
310
311 <p><small><font color="#0000e0">(<super>*</super>)</font> =
312 Enough for root-on-nfs, but not for disk boot.)</small>
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 </body>
345 </html>

  ViewVC Help
Powered by ViewVC 1.1.26