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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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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 1.100 2006/11/04 06:40:20 debug Exp $
14    
15  Copyright (C) 2003-2005  Anders Gavare.  All rights reserved.  Copyright (C) 2003-2006  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 are supported?</a>
56      <li><a href="#translation">What kind of translation does GXemul use?</a>
57    <li><a href="#accuracy">Emulation accuracy</a>    <li><a href="#accuracy">Emulation accuracy</a>
58    <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>  
59  </ul>  </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    
# Line 66  SUCH DAMAGE. Line 68  SUCH DAMAGE.
68  <a name="overview"></a>  <a name="overview"></a>
69  <h3>Overview:</h3>  <h3>Overview:</h3>
70    
71  GXemul is a machine emulator, which can be used to experiment with  GXemul is an experimental instruction-level machine emulator. Several
72  binary code for (among others) MIPS-based machines. Several emulation  emulation modes are available. In some modes, processors and surrounding
 modes are available. For some emulation modes, processors and surrounding  
73  hardware components are emulated well enough to let unmodified operating  hardware components are emulated well enough to let unmodified operating
74  systems run as if they were running on a real machine.  systems (e.g. NetBSD) run as if they were running on a real machine.
75    
76  <p>  <p>Devices and processors are not simulated with 100% accuracy. They are
77  Devices and CPUs are not simulated with 100% accuracy. They are only  only ``faked'' well enough to allow guest operating systems to run without
78  "faked" well enough to make operating systems (eg NetBSD) run without  complaining too much. Still, the emulator could be of interest for
79  complaining too much. Still, the emulator could be of interest for  academic research and experiments, such as when learning how to write
 academic research and experiments, such as when learning how to write  
80  operating system code.  operating system code.
81    
82  <p>  <p>The emulator is written in C, does not depend on third-party libraries,
83  The emulator is written in C, does not depend on external libraries (except  and should compile and run on most 64-bit and 32-bit Unix-like systems.
 X11, but that is optional), and should compile and run on most Unix-like  
 systems. If it doesn't, then that is a bug.  
 (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.)  
84    
85  <p>  <p>The emulator contains code which tries to emulate the workings of CPUs
86  The emulator contains code which tries to emulate the workings of CPUs and  and surrounding hardware found in real machines, but it does not contain
87  surrounding hardware found in real machines, but it does not contain any  any ROM code. You will need some form of program (in binary form) to run
88  ROM code. You will need some form of program (in binary form) to run in  in the emulator. For many emulation modes, PROM calls are handled by the
 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.  emulator itself, so you do not need to use any ROM image at all.
90    
91  <p>  <p>You can use pre-compiled kernels (for example NetBSD kernels, or
92  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
93  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
94  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).  
95    
96  <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  
97  disk image, then it is sometimes possible to boot directly from that  disk image, then it is sometimes possible to boot directly from that
98  image. (This works for example with DECstation emulation, or when booting  image. (This works for example with DECstation emulation, or when booting
99  from ISO9660 CDROM images.)  from ISO9660 CDROM images.)
100    
101    <p>Thanks to (in no specific order) Joachim Buss, Olivier Houchard, Juli
102    Mallett, Juan Romero Pardines, Alec Voropay, Göran Weinholt, Alexander
103    Yurchenko, and everyone else who has provided me with feedback.
104    
105    
106    
107    
108    
# 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  <p>  code, then you need to comply with each individual source file some other
133  (The licenses usually require that the original Copyright and license  way, for example by writing additional documentation containing copyright
134  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
135  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.
136  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
137    course, to let it remain open source and simply supply the source code.
138    
139    <p>In case you want to reuse parts of GXemul, but you need to do that
140    under a different license (e.g. the GPL), then contact me and I might
141    re-license/dual-license files on a case-by-case basis.
142    
143    
144    
# Line 152  Uncompress the .tar.gz distribution file Line 154  Uncompress the .tar.gz distribution file
154          $ <b>make</b>          $ <b>make</b>
155  </pre>  </pre>
156    
157  <p>  <p>This should work on most Unix-like systems. GXemul does not require any
158  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
159  mail me a bug report.  not have X11 libraries installed, some functionality will be lost.
160    
161  <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  
162  and on compiler settings, so you might want to experiment with different  and on compiler settings, so you might want to experiment with different
163  CC and CFLAGS environment variable values. For example, on a modern PC,  CC and CFLAGS environment variable values. For example, on an AMD Athlon
164  you could try the following:  host, you might want to try setting <tt>CFLAGS</tt> to <tt>-march=athlon</tt>
165  <p>  before running <tt>configure</tt>.
 <pre>  
         $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>  
         $ <b>make</b>  
 </pre>  
166    
 <p>  
 Run <b><tt>./configure --help</tt></b> to get a list of configure options. (The  
 possible options differ between different releases and snapshots.)  
167    
168    
169    
# Line 223  their original meaning in those xterm wi Line 213  their original meaning in those xterm wi
213    
214  <p><br>  <p><br>
215  <a name="cpus"></a>  <a name="cpus"></a>
216  <h3>Which CPU types does GXemul emulate?</h3>  <h3>Which processor architectures does GXemul emulate?</h3>
217    
218    The architectures that are emulated well enough to let at least one
219    guest operating system run (per architecture) are ARM, MIPS, PowerPC,
220    and SuperH.
221    
222    
223    
224    
225    
226    
227    <p><br>
228    <a name="hosts"></a>
229    <h3>Which host architectures are supported?</h3>
230    
231    GXemul should compile and run on any modern host architecture (64-bit or
232    32-bit word-length).
233    
234    <p>(The dynamic translation engine translates into an intermediate
235    representation, but not currently into native code. This means that there
236    is no need for per-host architecture backend code.)
237    
 <h4>MIPS:</h4>  
238    
 Emulation of R4000, which is a 64-bit CPU, was my initial goal.  
 R2000/R3000-like CPUs (32-bit), R1x000, and generic MIPS32/MIPS64-style  
 CPUs are also emulated, and are hopefully almost as stable as the R4000  
 emulation.  
239    
 <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.)  
240    
241    
242  <h4>URISC:</h4>  <p><br>
243    <a name="translation"></a>
244    <h3>What kind of translation does GXemul use?</h3>
245    
246    <b>Static vs. dynamic:</b>
247    
248  I have implemented an <a href="http://en.wikipedia.org/wiki/URISC">URISC</a>  <p>In order to support guest operating systems, which can overwrite old
249  emulation mode, just for fun. The only instruction available in an URISC  code pages in memory with new code, it is necessary to translate code
250  machine is "reverse subtract and skip on borrow". (It is probably not  dynamically. It is not possible to do a "one-pass" (static) translation.
251  worth trying to do bintrans with URISC, because any reasonable URISC  Self-modifying code and Just-in-Time compilers running inside
252  program relies on self-modifying code, which is bad for bintrans  the emulator are other things that would not work with a static
253  performance.)  translator. GXemul is a dynamic translator. However, it does not
254    necessarily translate into native code, like many other emulators.
255    
256    <p><b>"Runnable" Intermediate Representation:</b>
257    
258    <p>Dynamic translators usually translate from the emulated architecture
259    (e.g. MIPS) into a kind of <i>intermediate representation</i> (IR), and then
260    to native code (e.g. AMD64 or x86 code). Since one of my main goals for
261    GXemul is to keep everything as portable as possible, I have tried to make
262    sure that the IR is something which can be executed regardless of whether
263    the final step (translation from IR to native code) has been implemented
264    or not.
265    
266    <p>The IR in GXemul consists of arrays of pointers to functions, and a few
267    arguments which are passed along to those functions. The functions are
268    implemented in either manually hand-coded C, or automatically generated C.
269    In any case, this is all statically linked into the GXemul binary at link
270    time.
271    
272    <p>Here is a simplified diagram of how these arrays work.
273    
274    <p><center><img src="simplified_dyntrans.png"></center>
275    
276    <p>There is one instruction call slot for every possible program counter
277    location. In the MIPS case, instruction words are 32 bits in length,
278    and pages are (usually) 4 KB large, resulting in 1024 instruction call
279    slots. After the last of these instruction calls, there is an additional
280    call to a special "end of page" function (which doesn't count as an executed
281    instruction). This function switches to the first instruction
282    on the next virtual page (which might cause exceptions, etc).
283    
284    <p>The complexity of individual instructions vary. A simple example of
285    what an instruction can look like is the MIPS <tt>addiu</tt> instruction:
286    <pre>
287            X(addiu)
288            {
289                    reg(ic->arg[1]) = (int32_t)
290                        ((int32_t)reg(ic->arg[0]) + (int32_t)ic->arg[2]);
291            }
292    </pre>
293    
294  <h4>POWER/PowerPC</h4>  <p>It stores the result of a 32-bit addition of the register at arg[0]
295    with the immediate value arg[2] (treating both as signed 32-bit
296    integers) into register arg[1]. If the emulated CPU is a 64-bit CPU,
297    then this will store a correctly sign-extended value into arg[1].
298    If it is a 32-bit CPU, then only the lowest 32 bits will be stored,
299    and the high part ignored. <tt>X(addiu)</tt> is expanded to
300    <tt>mips_instr_addiu</tt> in the 64-bit case, and <tt>mips32_instr_addiu</tt>
301    in the 32-bit case. Both are compiled into the GXemul executable; no code
302    is created during run-time.
303    
304    <p>Here are examples of what the <tt>addiu</tt> instruction actually
305    looks like when it is compiled, on various host architectures:
306    
307    <p><center><table border="0">
308        <tr><td><b>GCC 4.0.1 on Alpha:</b></td>
309            <td width="35"></td><td></td>
310        <tr>
311            <td valign="top">
312    <pre>mips_instr_addiu:
313         ldq     t1,8(a1)
314         ldq     t2,24(a1)
315         ldq     t3,16(a1)
316         ldq     t0,0(t1)
317         addl    t0,t2,t0
318         stq     t0,0(t3)
319         ret</pre>
320            </td>
321            <td></td>
322            <td valign="top">
323    <pre>mips32_instr_addiu:
324         ldq     t2,8(a1)
325         ldq     t0,24(a1)
326         ldq     t3,16(a1)
327         ldl     t1,0(t2)
328         addq    t0,t1,t0
329         stl     t0,0(t3)
330         ret</pre>
331            </td>
332        </tr>
333    
334        <tr><td><b><br>GCC 3.4.4 on AMD64:</b></td>
335        <tr>
336            <td valign="top">
337    <pre>mips_instr_addiu:
338         mov    0x8(%rsi),%rdx
339         mov    0x18(%rsi),%rax
340         mov    0x10(%rsi),%rcx
341         add    (%rdx),%eax
342         cltq
343         mov    %rax,(%rcx)
344         retq</pre>
345            </td>
346            <td></td>
347            <td valign="top">
348    <pre>mips32_instr_addiu:
349         mov    0x8(%rsi),%rcx
350         mov    0x10(%rsi),%rdx
351         mov    (%rcx),%eax
352         add    0x18(%rsi),%eax
353         mov    %eax,(%rdx)
354         retq</pre>
355            </td>
356        </tr>
357    
358        <tr><td><b><br>GCC 4.0.1 on i386:</b></td>
359        <tr>
360            <td valign="top">
361    <pre>mips_instr_addiu:
362         mov    0x8(%esp),%eax
363         mov    0x8(%eax),%ecx
364         mov    0x4(%eax),%edx
365         mov    0xc(%eax),%eax
366         add    (%edx),%eax
367         mov    %eax,(%ecx)
368         cltd
369         mov    %edx,0x4(%ecx)
370         ret</pre>
371            </td>
372            <td></td>
373            <td valign="top">
374    <pre>mips32_instr_addiu:
375         mov    0x8(%esp),%eax
376         mov    0x8(%eax),%ecx
377         mov    0x4(%eax),%edx
378         mov    0xc(%eax),%eax
379         add    (%edx),%eax
380         mov    %eax,(%ecx)
381         ret</pre>
382            </td>
383        </tr>
384    </table></center>
385    
386  There is some code for 64-bit (and 32-bit) POWER/PowerPC emulation, enough  <p>On 64-bit hosts, there is not much difference, but on 32-bit hosts (and
387  to run "Hello World", but not enough to run complete operating systems.    to some extent on AMD64), the difference is enough to make it worthwhile.
 This mode isn't really working yet.  
388    
389    
390  <h4>Other CPU types:</h4>  <p><b>Performance:</b>
391    
392    <p>The performance of using this kind of runnable IR is obviously lower
393    than what can be achieved by emulators using native code generation, but
394    can be significantly higher than using a naive fetch-decode-execute
395    interpretation loop. In my opinion, using a runnable IR is an interesting
396    compromise.
397    
398    <p>The overhead per emulated instruction is usually around or below
399    approximately 10 host instructions. This is very much dependent on your
400    host architecture and what compiler and compiler switches you are using.
401    Added to this instruction count is (of course) also the C code used to
402    implement each specific instruction.
403    
404    <p><b>Instruction Combinations:</b>
405    
406    <p>Short, common instruction sequences can sometimes be replaced by a
407    "compound" instruction. An example could be a compare instruction followed
408    by a conditional branch instruction. The advantages of instruction
409    combinations are that
410    <ul>
411      <li>the amortized overhead per instruction is slightly reduced, and
412      <p>
413      <li>the host's compiler can make a good job at optimizing the common
414            instruction sequence.
415    </ul>
416    
417    <p>The special cases where instruction combinations give the most gain
418    are in the cores of string/memory manipulation functions such as
419    <tt>memset()</tt> or <tt>strlen()</tt>. The core loop can then (at least
420    to some extent) be replaced by a native call to the equivalent function.
421    
422    <p>The implementations of compound instructions still keep track of the
423    number of executed instructions, etc. When single-stepping, these
424    translations are invalidated, and replaced by normal instruction calls
425    (one per emulated instruction).
426    
427    <p><b>Native Code Back-ends: (not in this release)</b>
428    
429    <p>In theory, it will be possible to implement native code generation
430    (similar to what is used in high-performance emulators such as QEMU),
431    as long as that generated code abides to the C ABI on the host, but
432    for now I wanted to make sure that GXemul works without such native
433    code back-ends. For this reason, since release 0.4.0, GXemul is
434    completely free of native code back-ends.
435    
 Some other CPU architectures (such as x86) can also be partially emulated.  
 These are not enabled by default though, because of their unstable-ness.  
436    
437    
438    
# Line 270  These are not enabled by default though, Line 443  These are not enabled by default though,
443  <h3>Emulation accuracy:</h3>  <h3>Emulation accuracy:</h3>
444    
445  GXemul is an instruction-level emulator; things that would happen in  GXemul is an instruction-level emulator; things that would happen in
446  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
447  stalls or out-of-order execution). Still, instruction-level accuracy seems  stalls or out-of-order execution). Still, instruction-level accuracy seems
448  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
449  emulator.  emulator.
450    
451  <p>  <p>The existance of instruction and data caches is "faked" to let
452  Caches are by default not emulated. In some cases, the existance of caches  operating systems think that they are there, but for all practical
453  is "faked" to let operating systems think that they are there. (There is  purposes, these caches are non-working.
454  some old code for R2000/R3000 caches, but it has probably suffered from  
455  bitrot by now.)  <p>The emulator is in general <i>not</i> timing-accurate, neither at the
456    instruction level nor on any higher level. An attempt is made to let
457    emulated clocks run at the same speed as the host (i.e. an emulated timer
458    running at 100 Hz will interrupt around 100 times per real second), but
459    since the host speed may vary, e.g. because of other running processes,
460    there is no guarantee as to how many instructions will be executed in
461    each of these 100 Hz cycles.
462    
463    <p>If the host is very slow, the emulated clocks might even lag behind
464    the real-world clock.
465    
 <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.)  
466    
467    
468    
# Line 303  are emulated well enough to run at least Line 477  are emulated well enough to run at least
477    
478  <p>  <p>
479  <ul>  <ul>
480    <li><b>DECstation 5000/200</b>&nbsp;&nbsp;("3max")    <li><b><u>ARM</u></b>
481          <br>Serial controller (including keyboard and mouse), ethernet,    <ul>
482          SCSI, and graphical framebuffers.      <li><b>CATS</b> (<a href="guestoses.html#netbsdcatsinstall">NetBSD/cats</a>,
483            <a href="guestoses.html#openbsdcatsinstall">OpenBSD/cats</a>)
484        <li><b>IQ80321</b> (<a href="guestoses.html#netbsdevbarminstall">NetBSD/evbarm</a>)
485        <li><b>NetWinder</b> (<a href="guestoses.html#netbsdnetwinderinstall">NetBSD/netwinder</a>)
486      </ul>
487    <p>    <p>
488    <li><b>Acer Pica-61</b>&nbsp;&nbsp;(an ARC machine)    <li><b><u>MIPS</u></b>
489          <br>Serial controller, "VGA" text console, and SCSI.    <ul>
490        <li><b>DECstation 5000/200</b> (<a href="guestoses.html#netbsdpmaxinstall">NetBSD/pmax</a>,
491            <a href="guestoses.html#openbsdpmaxinstall">OpenBSD/pmax</a>,
492            <a href="guestoses.html#ultrixinstall">Ultrix</a>,
493            <a href="guestoses.html#declinux">Linux/DECstation</a>,
494            <a href="guestoses.html#sprite">Sprite</a>)
495        <li><b>Acer Pica-61</b> (<a href="guestoses.html#netbsdarcinstall">NetBSD/arc</a>)
496        <li><b>NEC MobilePro 770, 780, 800, 880</b> (<a href="guestoses.html#netbsdhpcmipsinstall">NetBSD/hpcmips</a>)
497        <li><b>Cobalt</b> (<a href="guestoses.html#netbsdcobaltinstall">NetBSD/cobalt</a>)
498        <li><b>Malta</b> (<a href="guestoses.html#netbsdevbmipsinstall">NetBSD/evbmips</a>)
499        <li><b>Algorithmics P5064</b> (<a href="guestoses.html#netbsdalgorinstall">NetBSD/algor</a>)
500        <li><b>SGI O2 (aka IP32)</b> <font color="#0000e0">(<super>*1</super>)</font>
501            (<a href="guestoses.html#netbsdsgimips">NetBSD/sgi</a>)
502      </ul>
503    <p>    <p>
504    <li><b>NEC MobilePro 770, 780, 800, and 880</b>&nbsp;&nbsp;(HPCmips machines)    <li><b><u>PowerPC</u></b>
505          <br>Framebuffer, keyboard, and a PCMCIA IDE controller.    <ul>
506        <li><b>IBM 6050/6070 (PReP, PowerPC Reference Platform)</b> (<a href="guestoses.html#netbsdprepinstall">NetBSD/prep</a>)
507      </ul>
508    <p>    <p>
509    <li><b>Cobalt</b>    <li><b><u>SuperH</u></b>
510          <br>Serial controller and PCI IDE.    <ul>
511        <li><b>Sega Dreamcast</b>
512            <font color="#0000e0">(<super>*2</super>)</font>
513            (<a href="guestoses.html#netbsddreamcast">NetBSD/dreamcast</a>)
514      </ul>
515  </ul>  </ul>
516    
517  <p>  <p>
518  There is code in GXemul for emulation of many other machine types;  <small><font color="#0000e0">(<super>*1</super>)</font> =
519  the degree to which these work range from "almost" being able to run  Enough for root-on-nfs, but not for disk boot.</small>
520  a complete OS, to almost completely unsupported (perhaps just enough  <br><small><font color="#0000e0">(<super>*2</super>)</font> =
521  support to output a few boot messages via serial console).  Only enough to reach ramdisk userland; no root-on-nfs yet.</small>
522    
523  <p>  <p>There is code in GXemul for emulation of many other machine types; the
524  In addition to emulating real machines, there is also a "test-machine".  degree to which these work range from almost being able to run a complete
525  A test-machine consists of one or more CPUs and a few experimental  OS, to almost completely unsupported (perhaps just enough support to
526  devices such as:  output a few boot messages via serial console).
527    
528    <p>In addition to emulating real machines, there is also a "test-machine".
529    A test-machine consists of one or more CPUs and a few experimental devices
530    such as:
531    
532  <p>  <p>
533  <ul>  <ul>
534    <li>a console I/O device (putchar() and getchar()...)    <li>a console I/O device (putchar() and getchar()...)
535    <li>an inter-processor communication device, for SMP experiments    <li>an inter-processor communication device, for SMP experiments
536    <li>a very simple linear framebuffer device (for graphics output)    <li>a very simple linear framebuffer device (for graphics output)
537      <li>a simple disk controller
538      <li>a simple ethernet controller
539      <li>a real-time clock device
540  </ul>  </ul>
541    
542  <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  
543  wish to target any specific real-world machine type, for example for  wish to target any specific real-world machine type, for example for
544  educational purposes.  educational purposes.
545    
546  <p>  <p>You can read more about these experimental devices <a
547  You can read more about these experimental devices  href="experiments.html#expdevices">here</a>.
 <a href="experiments.html#expdevices">here</a>.  
   
   
548    
549    
550    
551    
552    
 <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>  
   
   
 <p><br>  
   
 <super>*</super> Although Linux runs under DECstation emulation, the  
 default 2.4.27 kernel in Debian GNU/Linux does not support keyboards on  
 the 5000/200 (the specific DECstation model being emulated), so when the  
 login prompt is reached you cannot interact with the system. Kaj-Michael  
 Lang has compiled and made available a newer kernel from the current  
 mips-linux development tree. You can find it here: <a  
 href="http://home.tal.org/~milang/o2/kernels/">http://home.tal.org/~milang/o2/kernels</a>/<a  
 href="http://home.tal.org/~milang/o2/kernels/vmlinux-2.4.29-rc2-r3k-mipsel-decstation">vmlinux-2.4.29-rc2-r3k-mipsel-decstation</a>  
 This newer kernel supports keyboard input, but it does not have Debian's  
 ethernet patches, so you will not be able to use keyboard/framebuffer  
 <i>and</i> networking at the same time.  
   
553    
554  </body>  </body>
555  </html>  </html>

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