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3 | PSIM 1.0.1 - Model of the PowerPC Environments | |
4 | ||
5 | ||
6 | Copyright (C) 1994-1996, Andrew Cagney <cagney@highland.com.au>. | |
7 | ||
8 | This program is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
3fd725ef | 10 | the Free Software Foundation; either version 3 of the License, or |
c906108c SS |
11 | (at your option) any later version. |
12 | ||
13 | This program is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
51b318de | 19 | along with this program; if not, see <http://www.gnu.org/licenses/>. |
c906108c SS |
20 | |
21 | ||
22 | ---------------------------------------------------------------------- | |
23 | ||
24 | ||
25 | PSIM is a program written in extended ANSI-C that implements an | |
26 | instruction level simulation of the PowerPC environment. It is freely | |
27 | available in source code form under the terms of the GNU General | |
3fd725ef | 28 | Public License (version 3 or later). |
c906108c SS |
29 | |
30 | The PowerPC Architecture is described as having three levels of | |
31 | compliance: | |
32 | ||
33 | UEA - User Environment Architecture | |
34 | VEA - Virtual Environment Architecture | |
35 | OEA - Operating Environment Architecture | |
36 | ||
37 | PSIM both implements all three levels of the PowerPC and includes (for | |
38 | each level) a corresponding simulated run-time environment. | |
39 | ||
40 | In addition, PSIM, to the execution unit level, models the performance | |
41 | of most of the current PowerPC implementations (contributed by Michael | |
42 | Meissner). This detailed performance monitoring (unlike many other | |
43 | simulators) resulting in only a relatively marginal reduction in the | |
44 | simulators performance. | |
45 | ||
46 | ||
47 | A description of how to build PSIM is contained in the file: | |
48 | ||
49 | ftp://ftp.ci.com.au/pub/psim/INSTALL | |
50 | or ftp://cambridge.cygnus.com/pub/psim/INSTALL | |
51 | ||
52 | while an overview of how to use PSIM is in: | |
53 | ||
54 | ftp://ftp.ci.com.au/pub/psim/RUN | |
55 | or ftp://cambridge.cygnus.com/pub/psim/RUN | |
56 | ||
57 | This file is found in: | |
58 | ||
59 | ftp://ftp.ci.com.au/pub/psim/README | |
60 | or ftp://cambridge.cygnus.com/pub/psim/README | |
61 | ||
62 | ||
63 | Thanks goes firstly to: | |
64 | ||
65 | Corinthian Engineering Pty Ltd | |
66 | Cygnus Support | |
67 | Highland Logic Pty Ltd | |
68 | ||
69 | who provided the resources needed for making this software available | |
70 | on the Internet. | |
71 | ||
72 | More importantly I'd like to thank the following individuals who each | |
73 | contributed in their own unique way: | |
74 | ||
75 | Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam, | |
76 | Michael Meissner, Bob Mercier, Richard Perini, Dale Rahn, | |
77 | Richard Stallman, Mitchele Walker | |
78 | ||
79 | ||
80 | Andrew Cagney | |
81 | Feb, 1995 | |
82 | ||
83 | ||
84 | ---------------------------------------------------------------------- | |
85 | ||
86 | ||
87 | What features does PSIM include? | |
88 | ||
89 | Monitoring and modeling | |
90 | ||
91 | PSIM includes (thanks to Michael Meissner) | |
92 | a detailed model of most of the PowerPC | |
93 | implementations to the functional unit level. | |
94 | ||
95 | ||
96 | SMP | |
97 | ||
98 | The PowerPC ISA defines SMP synchronizing instructions. | |
99 | This simulator implements a limited, but functional, | |
100 | subset of the PowerPC synchronization instructions | |
101 | behaviour. Programs that restrict their synchronization | |
102 | primitives to those that work with this functional | |
103 | sub-set (eg P() and V()) are able to run on the SMP | |
104 | version of PSIM. | |
105 | ||
106 | People intending to use this system should study | |
107 | the code implementing the lwarx instruction. | |
108 | ||
109 | ENDIAN SUPPORT | |
110 | ||
111 | PSIM implements the PowerPC's big and little (xor | |
112 | endian) modes and correctly simulates code that | |
113 | switches between these two modes. | |
114 | ||
115 | In addition, psim can model a true little-endian | |
116 | machine. | |
117 | ||
118 | ISA (Instruction Set Architecture) models | |
119 | ||
120 | PSIM includes a model of the UEA, VEA and OEA. This | |
121 | includes the time base registers (VEA) and HTAB | |
122 | and BATS (OEA). | |
123 | ||
124 | In addition, a preliminary model of the 64 bit | |
125 | PowerPC architecture is implemented. | |
126 | ||
127 | IO Hardware | |
128 | ||
129 | PSIM's internals are based around the concept | |
130 | of a Device Tree. This tree intentionally | |
131 | resembles that of the Device Tree found in | |
132 | OpenBoot firmware. PSIM is flexible enough | |
133 | to allow the user to fully configure this device | |
134 | tree (and consequently the hardware model) at | |
135 | run time. | |
136 | ||
137 | Run-time environments: | |
138 | ||
139 | PSIM's UEA model includes emulation for BSD | |
140 | based UNIX system calls. | |
141 | ||
142 | PSIM's OEA model includes emulation of either: | |
143 | ||
144 | o OpenBoot client interface | |
145 | ||
146 | o MOTO's BUG interface. | |
147 | ||
148 | ||
149 | Floating point | |
150 | ||
151 | Preliminary support for floating point is included. | |
152 | ||
153 | ||
154 | Who would be interested in PSIM? | |
155 | ||
156 | o the curious | |
157 | ||
158 | Using psim, gdb, gcc and binutils the curious | |
159 | user can construct an environment that allows | |
160 | them to play with PowerPC Environment without | |
161 | the need for real hardware. | |
162 | ||
163 | ||
164 | o the analyst | |
165 | ||
166 | PSIM includes many (contributed) monitoring | |
167 | features which (unlike many other simulators) | |
168 | do not come with a great penalty in performance. | |
169 | ||
170 | Thus the performance analyst is able to use | |
171 | this simulator to analyse the performance of | |
172 | the system under test. | |
173 | ||
174 | If PSIM doesn't monitor a components of interest, | |
175 | the source code is freely available, and hence | |
176 | there is no hinderance to changing things | |
177 | to meet a specific analysts needs. | |
178 | ||
179 | ||
180 | o the serious SW developer | |
181 | ||
182 | PSIM models all three levels of the PowerPC | |
183 | Architecture: UEA, VEA and OEA. Further, | |
184 | the internal design is such that PSIM can | |
185 | be extended to support additional requirements. | |
186 | ||
187 | ||
188 | What performance analysis measurements can PSIM perform? | |
189 | ||
190 | Below is the output from a recent analysis run | |
191 | (contributed by Michael Meissner): | |
192 | ||
193 | For the following program: | |
194 | ||
195 | long | |
196 | simple_rand () | |
197 | { | |
198 | static unsigned long seed = 47114711; | |
199 | unsigned long this = seed * 1103515245 + 12345; | |
200 | seed = this; | |
201 | /* cut-cut-cut - see the file RUN.psim */ | |
202 | } | |
203 | ||
204 | Here is the current output generated with the -I switch on a P90 | |
205 | (the compiler used is the development version of GCC with a new | |
206 | scheduler replacing the old one): | |
207 | ||
208 | CPU #1 executed 41,994 AND instructions. | |
209 | CPU #1 executed 519,785 AND Immediate instructions. | |
210 | . | |
211 | . | |
212 | . | |
213 | CPU #1 executed 1 System Call instruction. | |
214 | CPU #1 executed 207,746 XOR instructions. | |
215 | ||
216 | CPU #1 executed 23,740,856 cycles. | |
217 | CPU #1 executed 10,242,780 stalls waiting for data. | |
218 | CPU #1 executed 1 stall waiting for a function unit. | |
219 | . | |
220 | . | |
221 | . | |
222 | CPU #1 executed 3,136,229 branch functional unit instructions. | |
223 | CPU #1 executed 16,949,396 instructions that were accounted for in timing info. | |
224 | CPU #1 executed 871,920 data reads. | |
225 | CPU #1 executed 971,926 data writes. | |
226 | CPU #1 executed 221 icache misses. | |
227 | CPU #1 executed 16,949,396 instructions in total. | |
228 | ||
229 | Simulator speed was 250,731 instructions/second | |
230 | ||
231 | ||
232 | What motivated PSIM? | |
233 | ||
234 | As an idea, psim was first discussed seriously during mid | |
235 | 1994. At that time its main objectives were: | |
236 | ||
237 | ||
238 | o good performance | |
239 | ||
240 | Many simulators loose out by only providing | |
241 | a binary interface to the internals. This | |
242 | interface eventually becomes a bottle neck | |
243 | in the simulators performance. | |
244 | ||
245 | It was intended that PSIM would avoid this | |
246 | problem by giving the user access to the | |
247 | full source code. | |
248 | ||
249 | Further, by exploiting the power of modern | |
250 | compilers it was hoped that PSIM would achieve | |
251 | good performance with out having to compromise | |
252 | its internal design. | |
253 | ||
254 | ||
255 | o practical portability | |
256 | ||
257 | Rather than try to be portable to every | |
258 | C compiler on every platform, it was decided | |
259 | that PSIM would restrict its self to supporting | |
260 | ANSI compilers that included the extension | |
261 | of a long long type. | |
262 | ||
263 | GCC is one such compiler, consequently PSIM | |
264 | should be portable to any machine running GCC. | |
265 | ||
266 | ||
267 | o flexibility in its design | |
268 | ||
269 | PSIM should allow the user to select the | |
270 | features required and customise the build | |
271 | accordingly. By having the source code, | |
272 | the compiler is able to eliminate any un | |
273 | used features of the simulator. | |
274 | ||
275 | After all, let the compiler do the work. | |
276 | ||
277 | ||
278 | o SMP | |
279 | ||
280 | A model that allowed the simulation of | |
281 | SMP platforms with out the large overhead | |
282 | often encountered with such models. | |
283 | ||
284 | ||
285 | PSIM achieves each of these objectives. | |
286 | ||
287 | ||
288 | Is PSIM PowerPC Platform (PPCP) (nee CHRP) Compliant? | |
289 | ||
290 | No. | |
291 | ||
292 | Among other things it does not have an Apple ROM socket. | |
293 | ||
294 | ||
295 | Could PSIM be extended so that it models a CHRP machine? | |
296 | ||
297 | Yes. | |
298 | ||
299 | PSIM has been designed with the CHRP spec in mind. To model | |
300 | a CHRP desktop the following would need to be added: | |
301 | ||
302 | o An apple ROM socket :-) | |
303 | ||
304 | o Model of each of the desktop IO devices | |
305 | ||
306 | o An OpenPIC device. | |
307 | ||
308 | o RTAS (Run Time Abstraction Services). | |
309 | ||
310 | o A fully populated device tree. | |
311 | ||
312 | ||
313 | Is the source code available? | |
314 | ||
315 | Yes. | |
316 | ||
317 | The source code to PSIM is available under the terms of | |
318 | the GNU Public Licence. This allows you to distribute | |
319 | the source code for free but with certain conditions. | |
320 | ||
321 | See the file: | |
322 | ||
323 | ftp://archie.au/gnu/COPYING | |
324 | ||
325 | For details of the terms and conditions. | |
326 | ||
327 | ||
328 | Where do I send bugs or report problems? | |
329 | ||
330 | There is a mailing list (subscribe through majordomo@ci.com.au) at: | |
331 | ||
332 | powerpc-psim@ci.com.au | |
333 | ||
334 | If I get the ftp archive updated I post a note to that mailing list. | |
335 | In addition your welcome to send bugs or problems either to me or to | |
336 | that e-mail list. | |
337 | ||
338 | This list currently averages zero articles a day. | |
339 | ||
340 | ||
341 | Does PSIM have any limitations or problems? | |
342 | ||
343 | PSIM can't run rs6000/AIX binaries - At present PSIM can only | |
344 | simulate static executables. Since an AIX executable is | |
345 | never static, PSIM is unable to simulate its execution. | |
346 | ||
347 | PSIM is still under development - consequently there are going | |
348 | to be bugs. | |
349 | ||
350 | See the file BUGS (included in the distribution) for any | |
351 | other outstanding issues. | |
352 |