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$Id: intro.html,v 1.61 2005/08/16 05:15:24 debug Exp $ |
$Id: intro.html,v 1.66 2005/11/23 22:03:24 debug Exp $ |
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Copyright (C) 2003-2005 Anders Gavare. All rights reserved. |
Copyright (C) 2003-2005 Anders Gavare. All rights reserved. |
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<a name="overview"></a> |
<a name="overview"></a> |
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<h3>Overview:</h3> |
<h3>Overview:</h3> |
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GXemul is an experimental instruction-level machine emulator. It can be |
GXemul is an experimental instruction-level machine emulator. Several |
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used to run binary code for MIPS-based machines, regardless of host |
emulation modes are available. In some modes, processors and surrounding |
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platform. Several emulation modes are available. For some modes, |
hardware components are emulated well enough to let unmodified operating |
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processors and surrounding hardware components are emulated well enough to |
systems (e.g. NetBSD) run as if they were running on a real machine. |
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let unmodified operating systems run as if they were running on a real |
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machine. |
<p>The processor architecture best emulated by GXemul is MIPS, but other |
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architectures such as ARM and PowerPC are also partially emulated. |
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<p>(Non-MIPS emulation modes are also under development, but so far none |
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of those modes has reached the completeness required to run unmodified |
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operating systems.) |
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<p>Devices and CPUs are not simulated with 100% accuracy. They are only |
<p>Devices and CPUs are not simulated with 100% accuracy. They are only |
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``faked'' well enough to make operating systems (e.g. NetBSD) run without |
``faked'' well enough to allow guest operating systems run without |
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complaining too much. Still, the emulator could be of interest for |
complaining too much. Still, the emulator could be of interest for |
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academic research and experiments, such as when learning how to write |
academic research and experiments, such as when learning how to write |
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operating system code. |
operating system code. |
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<p>The emulator is written in C, does not depend on external libraries |
<p>The emulator is written in C, does not depend on third-party libraries |
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(except X11, but that is optional), and should compile and run on most |
(except X11, but that is optional), and should compile and run on most |
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Unix-like systems. If it doesn't, then that is a bug. |
Unix-like systems. |
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<p>The emulator contains code which tries to emulate the workings of CPUs |
<p>The emulator contains code which tries to emulate the workings of CPUs |
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and surrounding hardware found in real machines, but it does not contain |
and surrounding hardware found in real machines, but it does not contain |
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The "easiest way out" if you plan to redistribute code from GXemul is, of |
The "easiest way out" if you plan to redistribute code from GXemul is, of |
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course, to let it remain open source and simply supply the source code. |
course, to let it remain open source and simply supply the source code. |
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<p>(If a stable release of GXemul is packaged into binary form, and it is |
<p>(If a stable, unmodified release of GXemul is packaged into binary form, |
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obvious which version of GXemul was used to build the package, then it can |
and it is clear which version of GXemul was used to build the package, |
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be argued that the source code is available, just not in that specific |
then it can be argued that the source code is available, just not in that |
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package. Common sense should be used in this case, and not pedanticism.) |
specific package. Common sense should be used in this case, and not |
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pedanticism.) |
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<p>The emulator's performance is highly dependent on both runtime settings |
<p>The emulator's performance is highly dependent on both runtime settings |
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and on compiler settings, so you might want to experiment with different |
and on compiler settings, so you might want to experiment with different |
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CC and CFLAGS environment variable values. For example, on a modern PC, |
CC and CFLAGS environment variable values. For example, on an AMD Athlon |
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you could try the following: |
host, you might want to try setting <tt>CFLAGS</tt> to <tt>-march=athlon |
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<p><pre> |
-O3</tt> before running <tt>configure</tt>. |
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$ <b>CFLAGS="-mcpu=pentium4 -O3" ./configure</b> |
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$ <b>make</b> |
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</pre> |
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Emulation of R4000, which is a 64-bit CPU, was my initial goal. |
Emulation of R4000, which is a 64-bit CPU, was my initial goal. |
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R2000/R3000-like CPUs (32-bit), R1x000, and generic MIPS32/MIPS64-style |
R2000/R3000-like CPUs (32-bit), R1x000, and generic MIPS32/MIPS64-style |
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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 |
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emulation. |
emulation. Several guest operating systems for MIPS can run inside |
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the emulator. |
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<p>I have written an experimental dynamic binary translation subsystem. |
<p>(For MIPS emulation, I have written an experimental dynamic binary |
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This gives higher total performance than interpreting one instruction at a |
translation subsystem, for Alpha and i386 hosts. This gives higher total |
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time and executing it. (If you wish to disable bintrans, add <b>-B</b> to |
performance than interpreting one instruction at a time and executing it. |
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the command line.) |
If you wish to disable bintrans, add <b>-B</b> to the command line.) |
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<h4>ARM:</h4> |
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<h4>Other CPU types:</h4> |
ARM emulation is good enough to run NetBSD/cats 2.1 and OpenBSD/cats 3.8, |
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but it is not as tested or fine-tuned as the MIPS emulation mode. |
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Some other CPU architectures can also be partially emulated. These are not |
<h4>PowerPC:</h4> |
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working well enough yet to run guest operating systems. |
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PowerPC emulation is still in its beginning stages, but good enough |
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to run NetBSD/prep 2.1. |
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<p>Non-MIPS emulation modes use dynamic translation, but not recompilation |
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into native code. This makes it possible to run on any host platform. |
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option. (Deterministic in this case does <i>not</i> mean that the |
option. (Deterministic in this case does <i>not</i> mean that the |
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emulation will be identical to some actual real-world machine.) |
emulation will be identical to some actual real-world machine.) |
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<p><font color="#ff0000">(Oops/TODO: User interaction means <i>both</i> |
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input to the emulated program/OS, and interacting with the emulator |
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itself. Breaking into the debugger and then continuing execution may |
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affect when/how interrupts occur.)</font> |
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<p> |
<p> |
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<ul> |
<ul> |
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<li><b>DECstation 5000/200</b> ("3max") |
<li><b><u>MIPS</u></b> |
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<br>Serial controller (including keyboard and mouse), ethernet, |
<ul> |
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SCSI, and graphical framebuffers. |
<li><b>DECstation 5000/200</b> ("3max") |
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<p> |
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<li><b>Acer Pica-61</b> (an ARC machine) |
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<p> |
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<li><b>NEC MobilePro 770, 780, 800, and 880</b> (HPCmips machines) |
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<p> |
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<li><b>Cobalt</b> |
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<p> |
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<li><b>Malta</b> (evbmips) |
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<p> |
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<li><b>SGI O2 ("IP32")</b> |
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<br><small>(Enough for root-on-nfs, but not for disk boot.)</small> |
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</ul> |
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<p> |
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<li><b>Acer Pica-61</b> (an ARC machine) |
<li><b><u>ARM</u></b> |
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<br>Serial controller, "VGA" text console, and SCSI. |
<ul> |
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<li><b>CATS</b> |
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</ul> |
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<p> |
<p> |
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<li><b>NEC MobilePro 770, 780, 800, and 880</b> (HPCmips machines) |
<li><b><u>PowerPC</u></b> |
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<br>Framebuffer, keyboard, and a PCMCIA IDE controller. |
<ul> |
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<p> |
<li><b>PReP (PowerPC Reference Platform)</b> |
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<li><b>Cobalt</b> |
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<br>Serial controller and PCI IDE. |
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<p> |
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<li><b>Malta (evbmips)</b> |
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<br>Serial controller and PCI IDE. |
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<p> |
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<li><b>SGI O2 ("IP32")</b> |
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<br>Serial controller and ethernet. <small>(Enough for |
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root-on-nfs, but not for disk boot.)</small> |
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</ul> |
</ul> |
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<p>There is code in GXemul for emulation of many other machine types; the |
<p>There is code in GXemul for emulation of many other machine types; the |
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<td></td> |
<td></td> |
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</tr> |
</tr> |
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<tr><td height="10"></td></tr> |
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<tr> |
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<td></td> |
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<td align="center"><a href="20051007-netbsd-cats-installed.png"><img src="20051007-netbsd-cats-installed_small.png"></a></td> |
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<td></td> |
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<td><a href="http://www.netbsd.org/Ports/cats/">NetBSD/cats</a> |
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<br>CATS</td> |
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<td></td> |
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<td align="center"><a href="20051007-openbsd-cats-installed.png"><img src="20051007-openbsd-cats-installed_small.png"></a></td> |
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<td></td> |
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<td><a href="http://www.openbsd.org/cats.html">OpenBSD/cats</a> |
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<br>CATS</td> |
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<td></td> |
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</tr> |
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<tr><td height="10"></td></tr> |
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<tr> |
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<td></td> |
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<td align="center"><a href="20051123-netbsd-prep.png"><img src="20051123-netbsd-prep_small.png"></a></td> |
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<td></td> |
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<td><a href="http://www.netbsd.org/Ports/prep/">NetBSD/prep</a> |
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<br>PReP</td> |
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<td></td> |
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</tr> |
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</table></center> |
</table></center> |
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