/[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!

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-revision 10 by dpavlin,
Mon Oct  8 16:18:27 2007 UTC
+revision 14 by dpavlin,
Mon Oct  8 16:18:51 2007 UTC
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- <html>
+ <html><head><title>Gavare's eXperimental Emulator:&nbsp;&nbsp;&nbsp;Introduction</title>
- <head><title>GXemul documentation: Introduction</title>
+ <meta name="robots" content="noarchive,nofollow,noindex"></head>
- <meta name="robots" content="noarchive,nofollow,noindex">
- </head>
  <body bgcolor="#f8f8f8" text="#000000" link="#4040f0" vlink="#404040" alink="#ff0000">
  <table border=0 width=100% bgcolor="#d0d0d0"><tr>
  <td width=100% align=center valign=center><table border=0 width=100%><tr>
  <td align="left" valign=center bgcolor="#d0efff"><font color="#6060e0" size="6">
- <b>GXemul documentation:</b></font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
+ <b>Gavare's eXperimental Emulator:&nbsp;&nbsp;&nbsp;</b></font>
  <font color="#000000" size="6"><b>Introduction</b>
  </font></td></tr></table></td></tr></table><p>
  <!--
- $Id: intro.html,v 1.53 2005/06/26 08:42:26 debug Exp $
+ $Id: intro.html,v 1.64 2005/10/07 22:45:33 debug Exp $
  Copyright (C) 2003-2005  Anders Gavare.  All rights reserved.
-Line 66 
 SUCH DAMAGE.
+Line 64 
 SUCH DAMAGE.
  <a name="overview"></a>
  <h3>Overview:</h3>
- GXemul is an experimental instruction-level machine emulator. It can be
+ GXemul is an experimental instruction-level machine emulator. Several
- used to run binary code for (among others) MIPS-based machines, regardless
+ emulation modes are available. In some modes, processors and surrounding
- of host platform. Several emulation modes are available. For some modes,
+ hardware components are emulated well enough to let unmodified operating
- processors and surrounding hardware components are emulated well enough to
+ systems (e.g. NetBSD) run as if they were running on a real machine.
- let unmodified operating systems run as if they were running on a real
- machine.
+ <p>The processor architecture best emulated by GXemul is MIPS, but other
+ architectures are also partially emulated.
  <p>Devices and CPUs are not simulated with 100% accuracy. They are only
  ``faked'' well enough to make operating systems (e.g. NetBSD) run without
-Line 81 
 operating system code.
+Line 80 
 operating system code.
  <p>The emulator is written in C, does not depend on external libraries
  (except 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
+ Unix-like systems. If it doesn't, then that is a bug.
- 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
-Line 119 
 confusing to you, you might want to read
+Line 115 
 confusing to you, you might want to read
  four freedoms associated with Free software, <a
  href="http://www.gnu.org/philosophy/free-sw.html">http://www.gnu.org/philosophy/free-sw.html</a>.)
- <p>
+ <p>The code I have written is released under a 3-clause BSD-style license
- The code I have written is released under a 3-clause BSD-style license
+ (or "revised BSD-style" if one wants to use <a
- (or "revised BSD-style" if one wants to use
+ href="http://www.gnu.org/philosophy/bsd.html">GNU jargon</a>). Apart from
- <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
- 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
- such as NetBSD, for example header files containing symbolic names of
+ device registers. They are also covered by similar licenses, but with some
- bitfields in device registers. They are also covered by similar licenses,
+ additional clauses. The main point, however, is that the licenses require
- but with some additional clauses. If you plan to redistribute GXemul
+ that the original Copyright and license terms are included when you make a
- (for example as a binary package), or reuse code from GXemul,
+ copy or modification.
- then you should check those files for their license terms.
+ <p>If you plan to redistribute GXemul <i>without</i> supplying the source
+ code, then you need to comply with each individual source file some other
+ way, for example by writing additional documentation containing copyright
+ notes. I have not done this, since I do not plan on making distributions
+ without source code. You need to check all individual files for details.
+ The "easiest way out" if you plan to redistribute code from GXemul is, of
+ course, to let it remain open source and simply supply the source code.
+ <p>(If a stable, unmodified release of GXemul is packaged into binary form,
+ and it is clear which version of GXemul was used to build the package,
+ then it can be argued that the source code is available, just not in that
+ specific package. Common sense should be used in this case, and not
+ pedanticism.)
- <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.)
-Line 150 
 Uncompress the .tar.gz distribution file
+Line 154 
 Uncompress the .tar.gz distribution file
          $ <b>make</b>
  </pre>
- <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
  mail me a bug report.
- <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
  and on compiler settings, so you might want to experiment with different
  CC and CFLAGS environment variable values. For example, on a modern PC,
  you could try the following:
- <p>
+ <p><pre>
- <pre>
+         $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>
-         $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b>
+         $ <b>make</b>
-         $ <b>make</b>
  </pre>
- <p>
- Run <b><tt>./configure --help</tt></b> to get a list of configure options. (The
- possible options differ between different releases and snapshots.)
-Line 230 
 R2000/R3000-like CPUs (32-bit), R1x000,
+Line 224 
 R2000/R3000-like CPUs (32-bit), R1x000,
  CPUs are also emulated, and are hopefully almost as stable as the R4000
  emulation.
- <p>
+ <p>I have written an experimental dynamic binary translation subsystem.
- 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
+ time and executing it. (If you wish to disable bintrans, add <b>-B</b> to
- the command line, but keep in mind that it is still experimental.)
+ the command line.)
- <h4>URISC:</h4>
+ <h4>ARM:</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.)
+ The ARM CPU emulation is good enough to run NetBSD/cats and OpenBSD/cats
+ (almost bugfree :-), but it is not as tested or fine-tuned as the MIPS
+ emulation.
  <h4>Other CPU types:</h4>
-Line 267 
 stalls or out-of-order execution). Still
+Line 255 
 stalls or out-of-order execution). Still
  to be enough to be able to run complete guest operating systems inside the
  emulator.
- <p>
+ <p>Caches are by default not emulated. In some cases, the existance of
- 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.
- 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
- some old code for R2000/R3000 caches, but it has probably suffered from
+ suffered from bitrot by now.)
- bitrot by now.)
+ <p>The emulator is <i>not</i> timing-accurate. It can be run in a
- <p>
+ "deterministic" mode, <tt><b>-D</b></tt>. The meaning of deterministic is
- 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
- "deterministic" mode, <tt><b>-D</b></tt>. The meaning of deterministic is
+ identical runs. Obviously, this requires that no user interaction is
- 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>
- identical runs. Obviously, this requires that no user interaction is
+ option. (Deterministic in this case does <i>not</i> mean that the
- 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.)
-Line 295 
 are emulated well enough to run at least
+Line 281 
 are emulated well enough to run at least
  <p>
  <ul>
-   <li><b>DECstation 5000/200</b>&nbsp;&nbsp;("3max")
+   <li><b><u>MIPS</u></b>
+   <ul>
+     <li><b>DECstation 5000/200</b>&nbsp;&nbsp;("3max")
          <br>Serial controller (including keyboard and mouse), ethernet,
          SCSI, and graphical framebuffers.
-   <p>
+     <p>
-   <li><b>Acer Pica-61</b>&nbsp;&nbsp;(an ARC machine)
+     <li><b>Acer Pica-61</b>&nbsp;&nbsp;(an ARC machine)
          <br>Serial controller, "VGA" text console, and SCSI.
-   <p>
+     <p>
-   <li><b>NEC MobilePro 770, 780, 800, and 880</b>&nbsp;&nbsp;(HPCmips machines)
+     <li><b>NEC MobilePro 770, 780, 800, and 880</b>&nbsp;&nbsp;(HPCmips machines)
          <br>Framebuffer, keyboard, and a PCMCIA IDE controller.
-   <p>
+     <p>
-   <li><b>Cobalt</b>
+     <li><b>Cobalt</b>
          <br>Serial controller and PCI IDE.
-   <p>
+     <p>
-   <li><b>Malta (evbmips)</b>
+     <li><b>Malta (evbmips)</b>
          <br>Serial controller and PCI IDE.
-   <p>
+     <p>
-   <li><b>SGI O2 ("IP32")</b>
+     <li><b>SGI O2 ("IP32")</b>
          <br>Serial controller and ethernet.&nbsp;&nbsp;<small>(Enough for
          root-on-nfs, but not for disk boot.)</small>
+   </ul>
+   <p>
+   <li><b><u>ARM</u></b>
+   <ul>
+     <li><b>CATS</b>
+         <br>VGA and PCI IDE.
+   </ul>
  </ul>
  <p>There is code in GXemul for emulation of many other machine types; the
-Line 330 
 such as:
+Line 325 
 such as:
    <li>a console I/O device (putchar() and getchar()...)
    <li>an inter-processor communication device, for SMP experiments
    <li>a very simple linear framebuffer device (for graphics output)
+   <li>a simple SCSI disk controller
+   <li>a simple ethernet controller
  </ul>
  <p>This mode is useful if you wish to run experimental code, but do not
-Line 444 
 interacted with similar to a real machin
+Line 441 
 interacted with similar to a real machin
            <td></td>
          </tr>
+         <tr><td height="10"></td></tr>
+         <tr>
+           <td></td>
+           <td align="center"><a href="20051007-netbsd-cats-installed.png"><img src="20051007-netbsd-cats-installed_small.png"></a></td>
+           <td></td>
+           <td><a href="http://www.netbsd.org/Ports/cats/">NetBSD/cats</a>
+                 <br>CATS</td>
+           <td></td>
+           <td align="center"><a href="20051007-openbsd-cats-installed.png"><img src="20051007-openbsd-cats-installed_small.png"></a></td>
+           <td></td>
+           <td><a href="http://www.openbsd.org/cats.html">OpenBSD/cats</a>
+                 <br>CATS</td>
+           <td></td>
+         </tr>
  </table></center>

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