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1  <html>  <html><head><title>Gavare's eXperimental Emulator:&nbsp;&nbsp;&nbsp;Introduction</title>
2  <head><title>GXemul documentation: Introduction</title>  <meta name="robots" content="noarchive,nofollow,noindex"></head>
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3  <body bgcolor="#f8f8f8" text="#000000" link="#4040f0" vlink="#404040" alink="#ff0000">  <body bgcolor="#f8f8f8" text="#000000" link="#4040f0" vlink="#404040" alink="#ff0000">
4  <table border=0 width=100% bgcolor="#d0d0d0"><tr>  <table border=0 width=100% bgcolor="#d0d0d0"><tr>
5  <td width=100% align=center valign=center><table border=0 width=100%><tr>  <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">  <td align="left" valign=center bgcolor="#d0efff"><font color="#6060e0" size="6">
7  <b>GXemul documentation:</b></font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  <b>Gavare's eXperimental Emulator:</b></font><br>
8  <font color="#000000" size="6"><b>Introduction</b>  <font color="#000000" size="6"><b>Introduction</b>
9  </font></td></tr></table></td></tr></table><p>  </font></td></tr></table></td></tr></table><p>
10    
11  <!--  <!--
12    
13  $Id: intro.html,v 1.47 2005/06/04 22:47:49 debug Exp $  $Id: intro.html,v 1.118 2007/06/15 21:43:09 debug Exp $
14    
15  Copyright (C) 2003-2005  Anders Gavare.  All rights reserved.  Copyright (C) 2003-2007  Anders Gavare.  All rights reserved.
16    
17  Redistribution and use in source and binary forms, with or without  Redistribution and use in source and binary forms, with or without
18  modification, are permitted provided that the following conditions are met:  modification, are permitted provided that the following conditions are met:
# Line 47  SUCH DAMAGE. Line 45  SUCH DAMAGE.
45  <h2>Introduction</h2>  <h2>Introduction</h2>
46    
47  <p>  <p>
48    <table border="0" width="99%"><tr><td valign="top" align="left">
49  <ul>  <ul>
50    <li><a href="#overview">Overview</a>    <li><a href="#overview">Overview</a>
51    <li><a href="#free">Is GXemul Free software?</a>    <li><a href="#free">Is GXemul Free software?</a>
52    <li><a href="#build">How to compile/build the emulator</a>    <li><a href="#build">How to compile/build the emulator</a>
53    <li><a href="#run">How to run the emulator</a>    <li><a href="#run">How to run the emulator</a>
54    <li><a href="#cpus">Which CPU types does GXemul emulate?</a>    <li><a href="#cpus">Which processor architectures does GXemul emulate?</a>
55      <li><a href="#hosts">Which host architectures/platforms are supported?</a>
56    <li><a href="#accuracy">Emulation accuracy</a>    <li><a href="#accuracy">Emulation accuracy</a>
57    <li><a href="#emulmodes">Which machines does GXemul emulate?</a>    <li><a href="#emulmodes">Which machines does GXemul emulate?</a>
   <li><a href="#guestos">Which guest OSes are possible to run?</a>  
58  </ul>  </ul>
59    </td><td valign="center" align="center">
60    <a href="20050317-example.png"><img src="20050317-example_small.png"></a>
61    <p>NetBSD/pmax 1.6.2 with X11<br>running in GXemul</td></tr></table>
62    
63    
64    
# Line 66  SUCH DAMAGE. Line 67  SUCH DAMAGE.
67  <a name="overview"></a>  <a name="overview"></a>
68  <h3>Overview:</h3>  <h3>Overview:</h3>
69    
70  GXemul is a machine emulator, which can be used to experiment with  GXemul is an experimental <a href="#accuracy">instruction-level</a>
71  binary code for (among others) MIPS-based machines. Several emulation  machine emulator. Several emulation modes are available. In some modes,
72  modes are available. For some emulation modes, processors and surrounding  processors and surrounding hardware components are emulated well enough to
73  hardware components are emulated well enough to let unmodified operating  let <a href="#emulmodes">unmodified operating systems (e.g. NetBSD)
74  systems run as if they were running on a real machine.  run</a> as if they were running on a real machine.
75    
76  <p>  <p>The emulator is written in C, does not depend on third-party libraries,
77  Devices and CPUs are not simulated with 100% accuracy. They are only  and should compile and run on most 64-bit and 32-bit Unix-like systems,
78  "faked" well enough to make operating systems (eg NetBSD) run without  with few or no modifications.
79  complaining too much. Still, the emulator could be of interest for  
80  academic research and experiments, such as when learning how to write  <p>Devices and processors are not simulated with 100% accuracy. They are
81    only ``faked'' well enough to allow guest operating systems to run without
82    complaining too much. Still, the emulator could be of interest for
83    academic research and experiments, such as when learning how to write
84  operating system code.  operating system code.
85    
86  <p>  <p>The emulator contains code which tries to emulate the workings of CPUs
87  The emulator is written in C, does not depend on external libraries (except  and surrounding hardware found in real machines, but it does not contain
88  X11, but that is optional), and should compile and run on most Unix-like  any ROM code. You will need some form of program (in binary form) to run
89  systems. If it doesn't, then that is a bug.  in the emulator. For some emulation modes, PROM calls are handled by the
 (You do not need any MIPS compiler toolchain to build or use GXemul.  
 If you need to compile MIPS binaries from sources, then of course you need  
 such a toolchain, but that is completely separate from GXemul.)  
   
 <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  
90  emulator itself, so you do not need to use any ROM image at all.  emulator itself, so you do not need to use any ROM image at all.
91    
92  <p>  <p>You can use pre-compiled kernels (for example <a href="http://www.netbsd.org/">NetBSD</a>
93  You can use pre-compiled kernels (for example NetBSD kernels, or Linux),  kernels, or Linux), or other programs that are in binary format, and in some cases
94  or other programs that are in binary format, and in some cases even actual  even actual ROM images. A couple of different file formats are supported:
95  ROM images. A couple of different file formats are supported (ELF, a.out,  <a href="http://en.wikipedia.org/wiki/Executable_and_Linkable_Format">ELF</a>,
96  ECOFF, SREC, and raw binaries).  <a href="http://en.wikipedia.org/wiki/A.out">a.out</a>,
97    <a href="http://en.wikipedia.org/wiki/COFF">COFF</a>/<a href="http://en.wikipedia.org/wiki/ECOFF">ECOFF</a>,
98    <a href="http://en.wikipedia.org/wiki/SREC_%28file_format%29">SREC</a>, and raw binaries.
99    
100  <p>  <p>If you do not have a kernel as a separate file, but you have a bootable
 If you do not have a kernel as a separate file, but you have a bootable  
101  disk image, then it is sometimes possible to boot directly from that  disk image, then it is sometimes possible to boot directly from that
102  image. (This works for example with DECstation emulation, or when booting  image. This works for example with DECstation emulation, <a href="dreamcast.html">Dreamcast
103  from ISO9660 CDROM images.)  emulation</a>, or when booting from generic <a href="http://en.wikipedia.org/wiki/ISO9660">ISO9660</a>
104    CDROM images if the kernel is included in the image as a plain file.
105    
106    <p>Thanks to (in no specific order) Joachim Buss, Olivier Houchard, Juli
107    Mallett, Juan Romero Pardines, Carl van Schaik, Miod Vallat, Alec Voropay,
108    Göran Weinholt, Alexander Yurchenko, and everyone else who has provided me
109    with feedback.
110    
111    
112    
113    
# Line 121  confusing to you, you might want to read Line 124  confusing to you, you might want to read
124  four freedoms associated with Free software, <a  four freedoms associated with Free software, <a
125  href="http://www.gnu.org/philosophy/free-sw.html">http://www.gnu.org/philosophy/free-sw.html</a>.)  href="http://www.gnu.org/philosophy/free-sw.html">http://www.gnu.org/philosophy/free-sw.html</a>.)
126    
127  <p>  <p>The code I have written is released under a 3-clause BSD-style license
128  The code I have written is released under a 3-clause BSD-style license  (or "revised BSD-style" if one wants to use <a
129  (or "revised BSD-style" if one wants to use  href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>). Apart from
130  <a href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>).  the code I have written, some files are copied from other sources such as
131  Apart from the code I have written, some files are copied from other sources  NetBSD, for example header files containing symbolic names of bitfields in
132  such as NetBSD, for example header files containing symbolic names of  device registers. They are also covered by similar licenses, but with some
133  bitfields in device registers. They are also covered by similar licenses,  additional clauses. The main point, however, is that the licenses require
134  but with some additional clauses. If you plan to redistribute GXemul  that the original Copyright and license terms are included when you make a
135  (for example as a binary package), or reuse code from GXemul,  copy or modification.
136  then you should check those files for their license terms.  
137    <p>If you plan to redistribute GXemul <i>without</i> supplying the source
138  <p>  code, then you need to comply with each individual source file some other
139  (The licenses usually require that the original Copyright and license  way, for example by writing additional documentation containing copyright
140  terms are included when you make a copy or modification. The "easiest way  notes. I have not done this, since I do not plan on making distributions
141  out" if you plan to redistribute code from GXemul is to simply supply  without source code. You need to check all individual files for details.
142  the source code. You should however check individual files for details.)  The "easiest way out" if you plan to redistribute code from GXemul is, of
143    course, to let it remain open source and simply supply the source code.
144    
145    <p>In case you want to reuse parts of GXemul, but you need to do that
146    under a different license (e.g. the GPL), then contact me and I might
147    re-license/dual-license files on a case-by-case basis.
148    
149    
150    
# Line 152  Uncompress the .tar.gz distribution file Line 160  Uncompress the .tar.gz distribution file
160          $ <b>make</b>          $ <b>make</b>
161  </pre>  </pre>
162    
163  <p>  <p>This should work on most Unix-like systems. GXemul does not require any
164  This should work on most Unix-like systems. If it doesn't, then  specific libraries to build, however, if you build on a system which does
165  mail me a bug report.  not have X11 libraries installed, some functionality will be lost.
166    
167  <p>  <p>The emulator's performance is highly dependent on both runtime settings
168  (Note for Windows users: there is a possibility that some releases  and on compiler settings, so you might want to experiment with
169  and/or snapshots will also work with Cygwin, but I can't promise that.)  using different CC and CFLAGS environment variable values when running the
170    <tt>configure</tt> script.
171  <p>  
172  The emulator's performance is highly dependent on both runtime settings  <p>Note that there is no <tt>make install</tt> functionality; package
173  and on compiler settings, so you might want to experiment with different  maintainers for individual operating systems solve this for their
174  CC and CFLAGS environment variable values. For example, on a modern PC,  corresponding OSes.
 you could try the following:  
 <p>  
 <pre>  
         $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>  
         $ <b>make</b>  
 </pre>  
175    
 <p>  
 Run <b><tt>./configure --help</tt></b> to get a list of configure options. (The  
 possible options differ between different releases and snapshots.)  
176    
177    
178    
# Line 189  Running <tt><b>gxemul</b></tt> without a Line 188  Running <tt><b>gxemul</b></tt> without a
188  <b><tt>-h</tt></b> or <b><tt>-H</tt></b> command line options) will  <b><tt>-h</tt></b> or <b><tt>-H</tt></b> command line options) will
189  display a help message.  display a help message.
190    
191  <p>  <p>To get some ideas about what is possible to run in the emulator, please
 To get some ideas about what is possible to run in the emulator, please  
192  read the section about <a href="guestoses.html">installing "guest"  read the section about <a href="guestoses.html">installing "guest"
193  operating systems</a>. If you are interested in using the emulator to  operating systems</a>. The most straight forward guest operating to
194  develop code on your own, then you should also read the section about  install is NetBSD/pmax; the instructions provided <a
195  <a href="experiments.html#hello">Hello World</a>.  href="guestoses.html#netbsdpmaxinstall">here</a> should let you install
196    NetBSD/pmax in a way very similar to how it is done on a real DECstation.
197    
198    <p>If you are interested in using the emulator to develop code on your
199    own, then you should also read the section about <a
200    href="experiments.html#hello">Hello World</a>.
201    
202  <p>  <p>To exit the emulator, type CTRL-C to enter the
 To exit the emulator, type CTRL-C to enter the  
203  single-step debugger, and then type <tt><b>quit</b></tt>.  single-step debugger, and then type <tt><b>quit</b></tt>.
204    
205  <p>  <p>If you are starting an emulation by entering settings directly on the
206  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
207  command line, and you are not using the <tt><b>-x</b></tt> option, then all  all terminal input and output will go to the main controlling terminal.
 terminal input and output will go to the main controlling terminal.  
208  CTRL-C is used to break into the debugger, so in order to send CTRL-C to  CTRL-C is used to break into the debugger, so in order to send CTRL-C to
209  the running (emulated) program, you may use CTRL-B.  the running (emulated) program, you may use CTRL-B. (This should be a
210  (This should be a reasonable compromise to allow the emulator to be usable  reasonable compromise to allow the emulator to be usable even on systems
211  even on systems without X Windows.)  without X Windows.)
212    
213  <p>  <p>There is no way to send an actual CTRL-B to the emulated program, when
214  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
215  typing in the main controlling terminal window. The solution is to either  use <a href="configfiles.html">configuration files</a>, or use
 use <a href="configfiles.html">configuration files</a>, or use  
216  <tt><b>-x</b></tt>. Both these solutions cause new xterms to be opened for  <tt><b>-x</b></tt>. Both these solutions cause new xterms to be opened for
217  each emulated serial port that is written to. CTRL-B and CTRL-C both have  each emulated serial port that is written to. CTRL-B and CTRL-C both have
218  their original meaning in those xterm windows.  their original meaning in those xterm windows.
# Line 223  their original meaning in those xterm wi Line 223  their original meaning in those xterm wi
223    
224  <p><br>  <p><br>
225  <a name="cpus"></a>  <a name="cpus"></a>
226  <h3>Which CPU types does GXemul emulate?</h3>  <h3>Which processor architectures does GXemul emulate?</h3>
   
 <h4>MIPS:</h4>  
227    
228  Emulation of R4000, which is a 64-bit CPU, was my initial goal.  The architectures that are emulated well enough to let at least one
229  R2000/R3000-like CPUs (32-bit), R1x000, and generic MIPS32/MIPS64-style  guest operating system run (per architecture) are ARM, MIPS, PowerPC,
230  CPUs are also emulated, and are hopefully almost as stable as the R4000  and SuperH.
231  emulation.  
232    <p>Please read the page about <a href="guestoses.html">guest operating
233    systems</a> for more information about the machines and operating systems
234    that can be considered "working" in the emulator. (There is some code in
235    GXemul for emulation of other architectures, but they are not stable or
236    complete enough to be listed among the "working" architectures.)
237    
 <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 enable bintrans, add <b>-b</b> to  
 the command line, but keep in mind that it is still experimental.)  
238    
239    
 <h4>URISC:</h4>  
240    
 I have implemented an <a href="http://en.wikipedia.org/wiki/URISC">URISC</a>  
 emulation mode, just for fun. The only instruction available in an URISC  
 machine is "reverse subtract and skip on borrow". (It is probably not  
 worth trying to do bintrans with URISC, because any reasonable URISC  
 program relies on self-modifying code, which is bad for bintrans  
 performance.)  
241    
242    
243  <h4>POWER/PowerPC</h4>  <p><br>
244    <a name="hosts"></a>
245    <h3>Which host architectures/platforms are supported?</h3>
246    
247  There is some code for 64-bit (and 32-bit) POWER/PowerPC emulation, enough  GXemul should compile and run on any modern host architecture (64-bit or
248  to run "Hello World", but not enough to run complete operating systems.    32-bit word-length). I generally test it on FreeBSD/amd64 6.x,
249  This mode isn't really working yet.  FreeBSD/alpha 4.x, sometimes also on Linux (various platforms), and every
250    now and then also on NetBSD inside the emulator itself (various platforms).
251    
252    <p>Note 1: The <a href="translation.html">dynamic translation</a> engine
253    does <i>not</i> require backends for native code generation to be written
254    for each individual host architecture; the intermediate representation
255    that the dyntrans system uses can be executed on any host architecture.
256    
257    <p>Note 2: Although GXemul may build and run on non-Unix-like platforms,
258    such as Cygwin, Unix-like systems are the primary platform. Some
259    functionality may be lost when running on Cygwin.
260    
261    
 <h4>Other CPU types:</h4>  
262    
 Some other CPU architectures (such as x86) can also be partially emulated.  
 These are not enabled by default though, because of their unstable-ness.  
263    
264    
265    
# Line 270  These are not enabled by default though, Line 270  These are not enabled by default though,
270  <h3>Emulation accuracy:</h3>  <h3>Emulation accuracy:</h3>
271    
272  GXemul is an instruction-level emulator; things that would happen in  GXemul is an instruction-level emulator; things that would happen in
273  several steps within a real CPU are not taken into account (eg. pipe-line  several steps within a real CPU are not taken into account (e.g. pipe-line
274  stalls or out-of-order execution). Still, instruction-level accuracy seems  stalls or out-of-order execution). Still, instruction-level accuracy seems
275  to be enough to be able to run complete guest operating systems inside the  to be enough to be able to run complete guest operating systems inside the
276  emulator.  emulator.
277    
278  <p>  <p>The existance of instruction and data caches is "faked" to let
279  Caches are by default not emulated. In some cases, the existance of caches  operating systems think that they are there, but for all practical
280  is "faked" to let operating systems think that they are there. (There is  purposes, these caches are non-working.
281  some old code for R2000/R3000 caches, but it has probably suffered from  
282  bitrot by now.)  <p>The emulator is in general <i>not</i> timing-accurate, neither at the
283    instruction level nor on any higher level. An attempt is made to let
284    emulated clocks run at the same speed as the host (i.e. an emulated timer
285    running at 100 Hz will interrupt around 100 times per real second), but
286    since the host speed may vary, e.g. because of other running processes,
287    there is no guarantee as to how many instructions will be executed in
288    each of these 100 Hz cycles.
289    
290    <p>If the host is very slow, the emulated clocks might even lag behind
291    the real-world clock.
292    
 <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.)  
293    
294    
295    
# Line 303  are emulated well enough to run at least Line 304  are emulated well enough to run at least
304    
305  <p>  <p>
306  <ul>  <ul>
307    <li><b>DECstation 5000/200</b>&nbsp;&nbsp;("3max")    <li><b><u>ARM</u></b>
308          <br>Serial controller (including keyboard and mouse), ethernet,    <ul>
309          SCSI, and graphical framebuffers.      <li><b>CATS</b> (<a href="guestoses.html#netbsdcatsinstall">NetBSD/cats</a>,
310            <a href="guestoses.html#openbsdcatsinstall">OpenBSD/cats</a>)
311        <li><b>IQ80321</b> (<a href="guestoses.html#netbsdevbarminstall">NetBSD/evbarm</a>)
312        <li><b>NetWinder</b> (<a href="guestoses.html#netbsdnetwinderinstall">NetBSD/netwinder</a>)
313      </ul>
314    <p>    <p>
315    <li><b>Acer Pica-61</b>&nbsp;&nbsp;(an ARC machine)    <li><b><u>MIPS</u></b>
316          <br>Serial controller, "VGA" text console, and SCSI.    <ul>
317        <li><b>DECstation 5000/200</b> (<a href="guestoses.html#netbsdpmaxinstall">NetBSD/pmax</a>,
318            <a href="guestoses.html#openbsdpmaxinstall">OpenBSD/pmax</a>,
319            <a href="guestoses.html#ultrixinstall">Ultrix</a>,
320            <a href="guestoses.html#declinux">Linux/DECstation</a>,
321            <a href="guestoses.html#sprite">Sprite</a>)
322        <li><b>Acer Pica-61</b> (<a href="guestoses.html#netbsdarcinstall">NetBSD/arc</a>)
323        <li><b>NEC MobilePro 770, 780, 800, 880</b> (<a href="guestoses.html#netbsdhpcmipsinstall">NetBSD/hpcmips</a>)
324        <li><b>Cobalt</b> (<a href="guestoses.html#netbsdcobaltinstall">NetBSD/cobalt</a>)
325        <li><b>Malta</b> (<a href="guestoses.html#netbsdevbmipsinstall">NetBSD/evbmips</a>, Linux/Malta <font color="#0000e0">(<super>*1</super>)</font>)
326        <li><b>Algorithmics P5064</b> (<a href="guestoses.html#netbsdalgorinstall">NetBSD/algor</a>)
327        <li><b>SGI O2 (aka IP32)</b> <font color="#0000e0">(<super>*2</super>)</font>
328            (<a href="guestoses.html#netbsdsgimips">NetBSD/sgi</a>)
329      </ul>
330    <p>    <p>
331    <li><b>NEC MobilePro 770, 780, 800, and 880</b>&nbsp;&nbsp;(HPCmips machines)    <li><b><u>PowerPC</u></b>
332          <br>Framebuffer, keyboard, and a PCMCIA IDE controller.    <ul>
333        <li><b>IBM 6050/6070 (PReP, PowerPC Reference Platform)</b> (<a href="guestoses.html#netbsdprepinstall">NetBSD/prep</a>)
334        <li><b>MacPPC (generic "G4" Macintosh)</b> (<a href="guestoses.html#netbsdmacppcinstall">NetBSD/macppc</a>)
335        <li><b>Artesyn PM/PPC</b> (<a href="guestoses.html#netbsdpmppc">NetBSD/pmppc</a>)
336      </ul>
337    <p>    <p>
338    <li><b>Cobalt</b>    <li><b><u>SuperH</u></b>
339          <br>Serial controller and PCI IDE.    <ul>
340        <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>)
341        <li><b>Landisk I-O DATA USL-5P</b> (<a href="guestoses.html#openbsdlandiskinstall">OpenBSD/landisk</a>)
342      </ul>
343  </ul>  </ul>
344    
345  <p>  <p>
346  There is code in GXemul for emulation of many other machine types;  <small><font color="#0000e0">(<super>*1</super>)</font> =
347  the degree to which these work range from "almost" being able to run  Linux/Malta may be run as a guest OS, however I have not yet found any stable
348  a complete OS, to almost completely unsupported (perhaps just enough  URL to pre-compiled Linux/Malta kernels. Thus, Linux/Malta emulation is not
349  support to output a few boot messages via serial console).  tested for every release of the emulator; sometimes it works, sometimes
350    it doesn't.</small>
351  <p>  
352  In addition to emulating real machines, there is also a "test-machine".  <br><small><font color="#0000e0">(<super>*2</super>)</font> =
353  A test-machine consists of one or more CPUs and a few experimental  SGI O2 emulation is enough for root-on-nfs, but not for disk boot.</small>
354  devices such as:  
355    <p>Note that of all of the machines above, none of them is emulated to
356    100%. The most complete emulation mode is probably the DECstation
357    5000/200. Things that will most likely <b>not</b> work include running
358    raw PROM images for most machines, SGI IRIX, MacOS X or Darwin, Windows
359    NT, or Dreamcast games.
360    
361    <p>There is code in GXemul for emulation of several other machine types; the
362    degree to which these work range from almost being able to run a complete
363    OS, to almost completely unsupported, perhaps just enough support to
364    output a few boot messages via serial console. (See the end of
365    <a href="guestoses.html#generalnotes">this section</a> on the Guest OSes
366    page for some examples, but remember that these do not necessarily work.)
367    
368    <p>In addition to emulating real machines, there is also a "test-machine".
369    A test-machine consists of one or more CPUs and a few experimental devices
370    such as:
371    
372  <p>  <p>
373  <ul>  <ul>
374    <li>a console I/O device (putchar() and getchar()...)    <li>a console I/O device (putchar() and getchar()...)
375    <li>an inter-processor communication device, for SMP experiments    <li>an inter-processor communication device, for SMP experiments
376    <li>a very simple linear framebuffer device (for graphics output)    <li>a very simple linear framebuffer device (for graphics output)
377      <li>a simple disk controller
378      <li>a simple ethernet controller
379      <li>a real-time clock device
380  </ul>  </ul>
381    
382  <p>  <p>This mode is useful if you wish to run experimental code, but do not
 This mode is useful if you wish to run experimental code, but do not  
383  wish to target any specific real-world machine type, for example for  wish to target any specific real-world machine type, for example for
384  educational purposes.  educational purposes.
385    
386  <p>  <p>You can read more about these experimental devices <a
387  You can read more about these experimental devices  href="experiments.html#expdevices">here</a>.
 <a href="experiments.html#expdevices">here</a>.  
   
   
   
   
   
   
388    
 <p><br>  
 <a name="guestos"></a>  
 <h3>Which guest OSes are possible to run?</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>  
   
 </table></center>  
389    
390    
 <p><br>  
391    
 <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.  
392    
393    
394  </body>  </body>

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