/[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

Diff of /trunk/doc/intro.html

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 8 by dpavlin, Mon Oct 8 16:18:19 2007 UTC revision 12 by dpavlin, Mon Oct 8 16:18:38 2007 UTC
# Line 1  Line 1 
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>
 <meta name="robots" content="noarchive,nofollow,noindex">  
 </head>  
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:&nbsp;&nbsp;&nbsp;</b></font>
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 1.61 2005/08/16 05:15:24 debug Exp $
14    
15  Copyright (C) 2003-2005  Anders Gavare.  All rights reserved.  Copyright (C) 2003-2005  Anders Gavare.  All rights reserved.
16    
# Line 55  SUCH DAMAGE. Line 53  SUCH DAMAGE.
53    <li><a href="#cpus">Which CPU types does GXemul emulate?</a>    <li><a href="#cpus">Which CPU types does GXemul emulate?</a>
54    <li><a href="#accuracy">Emulation accuracy</a>    <li><a href="#accuracy">Emulation accuracy</a>
55    <li><a href="#emulmodes">Which machines does GXemul emulate?</a>    <li><a href="#emulmodes">Which machines does GXemul emulate?</a>
56    <li><a href="#guestos">Which guest OSes are possible to run?</a>    <li><a href="#guestos">Which guest OSes are possible to run in GXemul?</a>
57  </ul>  </ul>
58    
59    
# Line 66  SUCH DAMAGE. Line 64  SUCH DAMAGE.
64  <a name="overview"></a>  <a name="overview"></a>
65  <h3>Overview:</h3>  <h3>Overview:</h3>
66    
67  GXemul is a machine emulator, which can be used to experiment with  GXemul is an experimental instruction-level machine emulator. It can be
68  binary code for (among others) MIPS-based machines. Several emulation  used to run binary code for MIPS-based machines, regardless of host
69  modes are available. For some emulation modes, processors and surrounding  platform. Several emulation modes are available. For some modes,
70  hardware components are emulated well enough to let unmodified operating  processors and surrounding hardware components are emulated well enough to
71  systems run as if they were running on a real machine.  let unmodified operating systems run as if they were running on a real
72    machine.
73    
74    <p>(Non-MIPS emulation modes are also under development, but so far none
75    of those modes has reached the completeness required to run unmodified
76    operating systems.)
77    
78  <p>  <p>Devices and CPUs are not simulated with 100% accuracy. They are only
79  Devices and CPUs are not simulated with 100% accuracy. They are only  ``faked'' well enough to make operating systems (e.g. NetBSD) run without
 "faked" well enough to make operating systems (eg NetBSD) run without  
80  complaining too much. Still, the emulator could be of interest for  complaining too much. Still, the emulator could be of interest for
81  academic research and experiments, such as when learning how to write  academic research and experiments, such as when learning how to write
82  operating system code.  operating system code.
83    
84  <p>  <p>The emulator is written in C, does not depend on external libraries
85  The emulator is written in C, does not depend on external libraries (except  (except X11, but that is optional), and should compile and run on most
86  X11, but that is optional), and should compile and run on most Unix-like  Unix-like systems. If it doesn't, then that is a bug.
87  systems. If it doesn't, then that is a bug.  
88  (You do not need any MIPS compiler toolchain to build or use GXemul.  <p>The emulator contains code which tries to emulate the workings of CPUs
89  If you need to compile MIPS binaries from sources, then of course you need  and surrounding hardware found in real machines, but it does not contain
90  such a toolchain, but that is completely separate from GXemul.)  any ROM code. You will need some form of program (in binary form) to run
91    in the emulator. For many emulation modes, PROM calls are handled by the
 <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  
92  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.
93    
94  <p>  <p>You can use pre-compiled kernels (for example NetBSD kernels, or
95  You can use pre-compiled kernels (for example NetBSD kernels, or Linux),  Linux), or other programs that are in binary format, and in some cases
96  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
97  ROM images. A couple of different file formats are supported (ELF, a.out,  (ELF, a.out, ECOFF, SREC, and raw binaries).
 ECOFF, SREC, and raw binaries).  
98    
99  <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  
100  disk image, then it is sometimes possible to boot directly from that  disk image, then it is sometimes possible to boot directly from that
101  image. (This works for example with DECstation emulation, or when booting  image. (This works for example with DECstation emulation, or when booting
102  from ISO9660 CDROM images.)  from ISO9660 CDROM images.)
# Line 111  from ISO9660 CDROM images.) Line 106  from ISO9660 CDROM images.)
106    
107    
108    
109    
110    
111  <p><br>  <p><br>
112  <a name="free"></a>  <a name="free"></a>
113  <h3>Is GXemul Free software?</h3>  <h3>Is GXemul Free software?</h3>
# Line 121  confusing to you, you might want to read Line 118  confusing to you, you might want to read
118  four freedoms associated with Free software, <a  four freedoms associated with Free software, <a
119  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>.)
120    
121  <p>  <p>The code I have written is released under a 3-clause BSD-style license
122  The code I have written is released under a 3-clause BSD-style license  (or "revised BSD-style" if one wants to use <a
123  (or "revised BSD-style" if one wants to use  href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>). Apart from
124  <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
125  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
126  such as NetBSD, for example header files containing symbolic names of  device registers. They are also covered by similar licenses, but with some
127  bitfields in device registers. They are also covered by similar licenses,  additional clauses. The main point, however, is that the licenses require
128  but with some additional clauses. If you plan to redistribute GXemul  that the original Copyright and license terms are included when you make a
129  (for example as a binary package), or reuse code from GXemul,  copy or modification.
130  then you should check those files for their license terms.  
131    <p>If you plan to redistribute GXemul <i>without</i> supplying the source
132    code, then you need to comply with each individual source file some other
133    way, for example by writing additional documentation containing copyright
134    notes. I have not done this, since I do not plan on making distributions
135    without source code. You need to check all individual files for details.
136    The "easiest way out" if you plan to redistribute code from GXemul is, of
137    course, to let it remain open source and simply supply the source code.
138    
139    <p>(If a stable release of GXemul is packaged into binary form, and it is
140    obvious which version of GXemul was used to build the package, then it can
141    be argued that the source code is available, just not in that specific
142    package. Common sense should be used in this case, and not pedanticism.)
143    
144    
 <p>  
 (The licenses usually require that the original Copyright and license  
 terms are included when you make a copy or modification. The "easiest way  
 out" if you plan to redistribute code from GXemul is to simply supply  
 the source code. You should however check individual files for details.)  
145    
146    
147    
# Line 152  Uncompress the .tar.gz distribution file Line 157  Uncompress the .tar.gz distribution file
157          $ <b>make</b>          $ <b>make</b>
158  </pre>  </pre>
159    
160  <p>  <p>This should work on most Unix-like systems. If it doesn't, then
 This should work on most Unix-like systems. If it doesn't, then  
161  mail me a bug report.  mail me a bug report.
162    
163  <p>  <p>The emulator's performance is highly dependent on both runtime settings
 (Note for Windows users: there is a possibility that some releases  
 and/or snapshots will also work with Cygwin, but I can't promise that.)  
   
 <p>  
 The emulator's performance is highly dependent on both runtime settings  
164  and on compiler settings, so you might want to experiment with different  and on compiler settings, so you might want to experiment with different
165  CC and CFLAGS environment variable values. For example, on a modern PC,  CC and CFLAGS environment variable values. For example, on a modern PC,
166  you could try the following:  you could try the following:
167  <p>  <p><pre>
168  <pre>          $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>
169          $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>          $ <b>make</b>
         $ <b>make</b>  
170  </pre>  </pre>
171    
 <p>  
 Run <b><tt>./configure --help</tt></b> to get a list of configure options. (The  
 possible options differ between different releases and snapshots.)  
172    
173    
174    
# Line 232  R2000/R3000-like CPUs (32-bit), R1x000, Line 227  R2000/R3000-like CPUs (32-bit), R1x000,
227  CPUs are also emulated, and are hopefully almost as stable as the R4000  CPUs are also emulated, and are hopefully almost as stable as the R4000
228  emulation.  emulation.
229    
230  <p>  <p>I have written an experimental dynamic binary translation subsystem.
 I have written an experimental dynamic binary translation subsystem.  
231  This gives higher total performance than interpreting one instruction at a  This gives higher total performance than interpreting one instruction at a
232  time and executing it. (If you wish to enable bintrans, add <b>-b</b> to  time and executing it. (If you wish to disable bintrans, add <b>-B</b> to
233  the command line, but keep in mind that it is still experimental.)  the command line.)
   
   
 <h4>URISC:</h4>  
   
 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.)  
   
   
 <h4>POWER/PowerPC</h4>  
   
 There is some code for 64-bit (and 32-bit) POWER/PowerPC emulation, enough  
 to run "Hello World", but not enough to run complete operating systems.    
 This mode isn't really working yet.  
234    
235    
236  <h4>Other CPU types:</h4>  <h4>Other CPU types:</h4>
237    
238  Some other CPU architectures (such as x86) can also be partially emulated.  Some other CPU architectures can also be partially emulated. These are not
239  These are not enabled by default though, because of their unstable-ness.  working well enough yet to run guest operating systems.
240    
241    
242    
243    
# Line 275  stalls or out-of-order execution). Still Line 253  stalls or out-of-order execution). Still
253  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
254  emulator.  emulator.
255    
256  <p>  <p>Caches are by default not emulated. In some cases, the existance of
257  Caches are by default not emulated. In some cases, the existance of caches  caches is "faked" to let operating systems think that they are there.
258  is "faked" to let operating systems think that they are there. (There is  (There is some old code for R2000/R3000 caches, but it has probably
259  some old code for R2000/R3000 caches, but it has probably suffered from  suffered from bitrot by now.)
260  bitrot by now.)  
261    <p>The emulator is <i>not</i> timing-accurate. It can be run in a
262  <p>  "deterministic" mode, <tt><b>-D</b></tt>. The meaning of deterministic is
263  The emulator is <i>not</i> timing-accurate. It can be run in a  simply that running two emulations with the same settings will result in
264  "deterministic" mode, <tt><b>-D</b></tt>. The meaning of deterministic is  identical runs. Obviously, this requires that no user interaction is
265  simply that running two emulations with the same settings will result in  taking place, and that clock speeds are fixed with the <tt><b>-I</b></tt>
266  identical runs. Obviously, this requires that no user interaction is  option. (Deterministic in this case does <i>not</i> mean that the
267  taking place, and that clock speeds are fixed with the <tt><b>-I</b></tt>  emulation will be identical to some actual real-world machine.)
 option. (Deterministic in this case does <i>not</i> mean that the emulation  
 will be identical to some actual real-world machine.)  
268    
269    
270    
# Line 315  are emulated well enough to run at least Line 291  are emulated well enough to run at least
291    <p>    <p>
292    <li><b>Cobalt</b>    <li><b>Cobalt</b>
293          <br>Serial controller and PCI IDE.          <br>Serial controller and PCI IDE.
294      <p>
295      <li><b>Malta (evbmips)</b>
296            <br>Serial controller and PCI IDE.
297      <p>
298      <li><b>SGI O2 ("IP32")</b>
299            <br>Serial controller and ethernet.&nbsp;&nbsp;<small>(Enough for
300            root-on-nfs, but not for disk boot.)</small>
301  </ul>  </ul>
302    
303  <p>  <p>There is code in GXemul for emulation of many other machine types; the
304  There is code in GXemul for emulation of many other machine types;  degree to which these work range from almost being able to run a complete
305  the degree to which these work range from "almost" being able to run  OS, to almost completely unsupported (perhaps just enough support to
306  a complete OS, to almost completely unsupported (perhaps just enough  output a few boot messages via serial console).
307  support to output a few boot messages via serial console).  
308    <p>In addition to emulating real machines, there is also a "test-machine".
309  <p>  A test-machine consists of one or more CPUs and a few experimental devices
310  In addition to emulating real machines, there is also a "test-machine".  such as:
 A test-machine consists of one or more CPUs and a few experimental  
 devices such as:  
311    
312  <p>  <p>
313  <ul>  <ul>
314    <li>a console I/O device (putchar() and getchar()...)    <li>a console I/O device (putchar() and getchar()...)
315    <li>an inter-processor communication device, for SMP experiments    <li>an inter-processor communication device, for SMP experiments
316    <li>a very simple linear framebuffer device (for graphics output)    <li>a very simple linear framebuffer device (for graphics output)
317      <li>a simple SCSI disk controller
318      <li>a simple ethernet controller
319  </ul>  </ul>
320    
321  <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  
322  wish to target any specific real-world machine type, for example for  wish to target any specific real-world machine type, for example for
323  educational purposes.  educational purposes.
324    
325  <p>  <p>You can read more about these experimental devices <a
326  You can read more about these experimental devices  href="experiments.html#expdevices">here</a>.
 <a href="experiments.html#expdevices">here</a>.  
327    
328    
329    
# Line 352  You can read more about these experiment Line 333  You can read more about these experiment
333    
334  <p><br>  <p><br>
335  <a name="guestos"></a>  <a name="guestos"></a>
336  <h3>Which guest OSes are possible to run?</h3>  <h3>Which guest OSes are possible to run in GXemul?</h3>
337    
338  This table lists the guest OSes that run well enough to be considered  This table lists the guest OSes that run well enough to be considered
339  working in the emulator. They can boot from a harddisk image and be  working in the emulator. They can boot from a harddisk image and be
# Line 433  interacted with similar to a real machin Line 414  interacted with similar to a real machin
414                  <br>Cobalt</td>                  <br>Cobalt</td>
415          </tr>          </tr>
416    
417            <tr><td height="10"></td></tr>
418    
419            <tr>
420              <td></td>
421              <td align="center"><a href="20050626-netbsd-sgimips-netboot.png"><img src="20050626-netbsd-sgimips-netboot_small.png"></a></td>
422              <td></td>
423              <td><a href="http://www.netbsd.org/Ports/sgimips/">NetBSD/sgimips</a>
424                    <br>SGI O2 ("IP32")</td>
425              <td></td>
426              <td align="center"><a href="20050622-netbsd-evbmips-malta.png"><img src="20050622-netbsd-evbmips-malta_small.png"></a></td>
427              <td></td>
428              <td><a href="http://www.netbsd.org/Ports/evbmips/">NetBSD/evbmips</a>
429                    <br>5Kc (and 4Kc) Malta<br>evaluation boards</td>
430              <td></td>
431            </tr>
432    
433  </table></center>  </table></center>
434    
435    

Legend:
Removed from v.8  
changed lines
  Added in v.12

  ViewVC Help
Powered by ViewVC 1.1.26