1 |
Gavare's eXperimental Emulator -- GXemul 0.4.0.1 |
2 |
==================================================== |
3 |
|
4 |
Copyright (C) 2003-2006 Anders Gavare. |
5 |
|
6 |
|
7 |
Overview -- What is GXemul? |
8 |
----------------------------- |
9 |
|
10 |
GXemul is an experimental instruction-level machine emulator. Several |
11 |
emulation modes are available. In some modes, processors and surrounding |
12 |
hardware components are emulated well enough to let unmodified operating |
13 |
systems (e.g. NetBSD) run as if they were running on a real machine. |
14 |
|
15 |
Processors (ARM, MIPS, PowerPC) are emulated using a kind of dynamic |
16 |
translation system. Performance is somewhere between traditional |
17 |
interpretation and recompilation into native code. However, the dynamic |
18 |
translation system used in GXemul does not (currently) generate native |
19 |
code, and thus does not require platform-specific back-ends. In plain |
20 |
English, this means that the dyntrans system works on any host platform. |
21 |
|
22 |
Possible uses of the emulator include: |
23 |
|
24 |
o) educational purposes, e.g. to learn how to write code for MIPS |
25 |
|
26 |
o) hobby operating system development; the emulator can be used as a |
27 |
complement to testing your code on real hardware |
28 |
|
29 |
o) running guest operating systems in a "sandboxed" environment |
30 |
|
31 |
o) compiling your source code inside a guest operating system which you |
32 |
otherwise would not have access to (e.g. various exotic ports of |
33 |
NetBSD), to make sure that your source code is portable to those |
34 |
platforms |
35 |
|
36 |
o) simulating (ethernet) networks of computers running various |
37 |
operating systems, to study their interaction with each other |
38 |
|
39 |
o) debugging code in general |
40 |
|
41 |
Use your imagination :-) |
42 |
|
43 |
|
44 |
GXemul's limitations |
45 |
-------------------- |
46 |
|
47 |
o) GXemul is not (in general) a cycle-accurate simulator, because it does |
48 |
not simulate things smaller than an instruction. Pipe-line stalls, |
49 |
instruction latency effects etc. are more or less completely ignored. |
50 |
|
51 |
o) Hardware devices have been implemented in an ad-hoc and as-needed |
52 |
manner, usually only enough to fool certain guest operating systems |
53 |
(e.g. NetBSD) that the hardware devices exist and function well |
54 |
enough for those guest operating systems to use them. |
55 |
|
56 |
A consequence of this is that a machine mode may be implemented well |
57 |
enough to run NetBSD for that machine mode, but other guest operating |
58 |
systems may not run at all, or behave strangely. |
59 |
|
60 |
|
61 |
Quick start |
62 |
----------- |
63 |
|
64 |
To compile, type './configure' and then 'make'. This should work on most |
65 |
Unix-like systems. If not, then please mail me a bug report. |
66 |
|
67 |
You might want to experiment with various CC and CFLAGS environment |
68 |
variable settings, to get optimum performance. |
69 |
|
70 |
If you are impatient, and want to try out running a guest operating system |
71 |
inside GXemul, read this: doc/guestoses.html#netbsdcatsinstall |
72 |
|
73 |
If you want to use GXemul for experimenting with code of your own, |
74 |
then I suggest you compile a Hello World program according to the tips |
75 |
listed here: doc/experiments.html#hello |
76 |
|
77 |
Please read the rest of the documentation in the doc/ sub-directory for |
78 |
more detailed information on how to use the emulator. |
79 |
|
80 |
|
81 |
Feedback |
82 |
-------- |
83 |
|
84 |
If you have found GXemul useful in some way, or feel like sending me |
85 |
comments or feedback in general, then mail me at anders(at)gavare.se. |
86 |
|