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-revision 8 by dpavlin,
Mon Oct  8 16:18:19 2007 UTC
+revision 38 by dpavlin,
Mon Oct  8 16:21:53 2007 UTC
 Line 1
- <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:</b></font><br>
  <font color="#000000" size="6"><b>Introduction</b>
  </font></td></tr></table></td></tr></table><p>
  <!--
- $Id: intro.html,v 1.47 2005/06/04 22:47:49 debug Exp $
+ $Id: intro.html,v 1.108 2007/04/12 16:57:22 debug Exp $
- Copyright (C) 2003-2005  Anders Gavare.  All rights reserved.
+ Copyright (C) 2003-2007  Anders Gavare.  All rights reserved.
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
-Line 47 
 SUCH DAMAGE.
+Line 45 
 SUCH DAMAGE.
  <h2>Introduction</h2>
  <p>
+ <table border="0" width="99%"><tr><td valign="top" align="left">
  <ul>
    <li><a href="#overview">Overview</a>
    <li><a href="#free">Is GXemul Free software?</a>
    <li><a href="#build">How to compile/build the emulator</a>
    <li><a href="#run">How to run the emulator</a>
-   <li><a href="#cpus">Which CPU types does GXemul emulate?</a>
+   <li><a href="#cpus">Which processor architectures does GXemul emulate?</a>
+   <li><a href="#hosts">Which host architectures are supported?</a>
    <li><a href="#accuracy">Emulation accuracy</a>
    <li><a href="#emulmodes">Which machines does GXemul emulate?</a>
-   <li><a href="#guestos">Which guest OSes are possible to run?</a>
  </ul>
+ </td><td valign="center" align="center">
+ <a href="20050317-example.png"><img src="20050317-example_small.png"></a>
+ <p>NetBSD/pmax 1.6.2 with X11<br>running in GXemul</td></tr></table>
-Line 66 
 SUCH DAMAGE.
+Line 67 
 SUCH DAMAGE.
  <a name="overview"></a>
  <h3>Overview:</h3>
- GXemul is a machine emulator, which can be used to experiment with
+ GXemul is an experimental instruction-level machine emulator. Several
- 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
  hardware components are emulated well enough to let unmodified operating
- 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.
- <p>
+ <p>Devices and processors are not simulated with 100% accuracy. They are
- Devices and CPUs are not simulated with 100% accuracy. They are only
+ only ``faked'' well enough to allow guest operating systems to run without
- "faked" well enough to make operating systems (eg NetBSD) run without
+ complaining too much. Still, the emulator could be of interest for
- 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
  operating system code.
- <p>
+ <p>The emulator is written in C, does not depend on third-party libraries,
- 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.)
- <p>
+ <p>The emulator contains code which tries to emulate the workings of CPUs
- 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
- 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
- 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
  emulator itself, so you do not need to use any ROM image at all.
- <p>
+ <p>You can use pre-compiled kernels (for example NetBSD kernels, or
- 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
- 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
- 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).
- <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
  disk image, then it is sometimes possible to boot directly from that
- image. (This works for example with DECstation emulation, or when booting
+ image. (This works for example with DECstation emulation, Dreamcast
- from ISO9660 CDROM images.)
+ emulation, or when booting from generic ISO9660 CDROM images if the
+ kernel is included in the image as a plain file.)
+ <p>Thanks to (in no specific order) Joachim Buss, Olivier Houchard, Juli
+ Mallett, Juan Romero Pardines, Alec Voropay, G�ran Weinholt, Alexander
+ Yurchenko, and everyone else who has provided me with feedback.
-Line 121 
 confusing to you, you might want to read
+Line 118 
 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
- <p>
+ code, then you need to comply with each individual source file some other
- (The licenses usually require that the original Copyright and license
+ way, for example by writing additional documentation containing copyright
- 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
- 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.
- 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
+ course, to let it remain open source and simply supply the source code.
+ <p>In case you want to reuse parts of GXemul, but you need to do that
+ under a different license (e.g. the GPL), then contact me and I might
+ re-license/dual-license files on a case-by-case basis.
-Line 152 
 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. GXemul does not require any
- 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
- mail me a bug report.
+ not have X11 libraries installed, some functionality will be lost.
- <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,
+ CC and CFLAGS environment variable values. For example, on an AMD Athlon
- you could try the following:
+ host, you might want to try setting <tt>CFLAGS</tt> to <tt>-march=athlon</tt>
- <p>
+ before running <tt>configure</tt>.
- <pre>
-         $ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</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 223 
 their original meaning in those xterm wi
+Line 213 
 their original meaning in those xterm wi
  <p><br>
  <a name="cpus"></a>
- <h3>Which CPU types does GXemul emulate?</h3>
+ <h3>Which processor architectures does GXemul emulate?</h3>
- <h4>MIPS:</h4>
- 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.
- <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.)
+ The architectures that are emulated well enough to let at least one
+ guest operating system run (per architecture) are ARM, MIPS, PowerPC,
+ and SuperH.
+ <p>Please read the page about <a href="guestoses.html">guest operating
+ systems</a> for more information about the machines and operating systems
+ that can be considered "working" in the emulator.
- <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.
+ <p><br>
+ <a name="hosts"></a>
+ <h3>Which host architectures are supported?</h3>
- <h4>Other CPU types:</h4>
+ GXemul should compile and run on any modern host architecture (64-bit or
+-bit word-length).
- Some other CPU architectures (such as x86) can also be partially emulated.
+ <p>Note: The <a href="translation.html">dynamic translation</a> engine
- These are not enabled by default though, because of their unstable-ness.
+ does <i>not</i> require backends for native code generation to be written
+ for each individual host architecture; the intermediate representation
+ that the dyntrans system uses can be executed on any host architecture.
-Line 270 
 These are not enabled by default though,
+Line 249 
 These are not enabled by default though,
  <h3>Emulation accuracy:</h3>
  GXemul is an instruction-level emulator; things that would happen in
- 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
  stalls or out-of-order execution). Still, instruction-level accuracy seems
  to be enough to be able to run complete guest operating systems inside the
  emulator.
- <p>
+ <p>The existance of instruction and data caches is "faked" to let
- Caches are by default not emulated. In some cases, the existance of caches
+ operating systems think that they are there, but for all practical
- is "faked" to let operating systems think that they are there. (There is
+ purposes, these caches are non-working.
- some old code for R2000/R3000 caches, but it has probably suffered from
- bitrot by now.)
+ <p>The emulator is in general <i>not</i> timing-accurate, neither at the
+ instruction level nor on any higher level. An attempt is made to let
+ emulated clocks run at the same speed as the host (i.e. an emulated timer
+ running at 100 Hz will interrupt around 100 times per real second), but
+ since the host speed may vary, e.g. because of other running processes,
+ there is no guarantee as to how many instructions will be executed in
+ each of these 100 Hz cycles.
+ <p>If the host is very slow, the emulated clocks might even lag behind
+ the real-world clock.
- <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.)
-Line 303 
 are emulated well enough to run at least
+Line 283 
 are emulated well enough to run at least
  <p>
  <ul>
-   <li><b>DECstation 5000/200</b>&nbsp;&nbsp;("3max")
+   <li><b><u>ARM</u></b>
-         <br>Serial controller (including keyboard and mouse), ethernet,
+   <ul>
-         SCSI, and graphical framebuffers.
+     <li><b>CATS</b> (<a href="guestoses.html#netbsdcatsinstall">NetBSD/cats</a>,
+         <a href="guestoses.html#openbsdcatsinstall">OpenBSD/cats</a>)
+     <li><b>IQ80321</b> (<a href="guestoses.html#netbsdevbarminstall">NetBSD/evbarm</a>)
+     <li><b>NetWinder</b> (<a href="guestoses.html#netbsdnetwinderinstall">NetBSD/netwinder</a>)
+   </ul>
    <p>
-   <li><b>Acer Pica-61</b>&nbsp;&nbsp;(an ARC machine)
+   <li><b><u>MIPS</u></b>
-         <br>Serial controller, "VGA" text console, and SCSI.
+   <ul>
+     <li><b>DECstation 5000/200</b> (<a href="guestoses.html#netbsdpmaxinstall">NetBSD/pmax</a>,
+         <a href="guestoses.html#openbsdpmaxinstall">OpenBSD/pmax</a>,
+         <a href="guestoses.html#ultrixinstall">Ultrix</a>,
+         <a href="guestoses.html#declinux">Linux/DECstation</a>,
+         <a href="guestoses.html#sprite">Sprite</a>)
+     <li><b>Acer Pica-61</b> (<a href="guestoses.html#netbsdarcinstall">NetBSD/arc</a>)
+     <li><b>NEC MobilePro 770, 780, 800, 880</b> (<a href="guestoses.html#netbsdhpcmipsinstall">NetBSD/hpcmips</a>)
+     <li><b>Cobalt</b> (<a href="guestoses.html#netbsdcobaltinstall">NetBSD/cobalt</a>)
+     <li><b>Malta</b> (<a href="guestoses.html#netbsdevbmipsinstall">NetBSD/evbmips</a>, Linux/Malta <font color="#0000e0">(<super>*1</super>)</font>)
+     <li><b>Algorithmics P5064</b> (<a href="guestoses.html#netbsdalgorinstall">NetBSD/algor</a>)
+     <li><b>SGI O2 (aka IP32)</b> <font color="#0000e0">(<super>*2</super>)</font>
+         (<a href="guestoses.html#netbsdsgimips">NetBSD/sgi</a>)
+   </ul>
    <p>
-   <li><b>NEC MobilePro 770, 780, 800, and 880</b>&nbsp;&nbsp;(HPCmips machines)
+   <li><b><u>PowerPC</u></b>
-         <br>Framebuffer, keyboard, and a PCMCIA IDE controller.
+   <ul>
+     <li><b>IBM 6050/6070 (PReP, PowerPC Reference Platform)</b> (<a href="guestoses.html#netbsdprepinstall">NetBSD/prep</a>)
+     <li><b>MacPPC (generic "G4" Macintosh)</b> (<a href="guestoses.html#netbsdmacppcinstall">NetBSD/macppc</a>)
+   </ul>
    <p>
-   <li><b>Cobalt</b>
+   <li><b><u>SuperH</u></b>
-         <br>Serial controller and PCI IDE.
+   <ul>
+     <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>)
+   </ul>
  </ul>
  <p>
- There is code in GXemul for emulation of many other machine types;
+ <small><font color="#0000e0">(<super>*1</super>)</font> =
- 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
- a complete OS, to almost completely unsupported (perhaps just enough
+ URL to pre-compiled Linux/Malta kernels. Thus, Linux/Malta emulation is not
- support to output a few boot messages via serial console).
+ tested for every release of the emulator; sometimes it works, sometimes
+ it doesn't.</small>
- <p>
- In addition to emulating real machines, there is also a "test-machine".
+ <br><small><font color="#0000e0">(<super>*2</super>)</font> =
- 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>
- devices such as:
+ <p>There is code in GXemul for emulation of many other machine types; the
+ degree to which these work range from almost being able to run a complete
+ OS, to almost completely unsupported (perhaps just enough support to
+ output a few boot messages via serial console).
+ <p>In addition to emulating real machines, there is also a "test-machine".
+ A test-machine consists of one or more CPUs and a few experimental devices
+ such as:
  <p>
  <ul>
    <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 disk controller
+   <li>a simple ethernet controller
+   <li>a real-time clock device
  </ul>
- <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
  wish to target any specific real-world machine type, for example for
  educational purposes.
- <p>
+ <p>You can read more about these experimental devices <a
- You can read more about these experimental devices
+ href="experiments.html#expdevices">here</a>.
- <a href="experiments.html#expdevices">here</a>.
- <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.
  </body>
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