1
2
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
10 the Free Software Foundation; either version 3 of the License, or
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
19 along with this program; if not, see <http://www.gnu.org/licenses/>.
20
21
22 ----------------------------------------------------------------------
23
24
25PSIM is a program written in extended ANSI-C that implements an
26instruction level simulation of the PowerPC environment. It is freely
27available in source code form under the terms of the GNU General
28Public License (version 3 or later).
29
30The PowerPC Architecture is described as having three levels of
31compliance:
32
33 UEA - User Environment Architecture
34 VEA - Virtual Environment Architecture
35 OEA - Operating Environment Architecture
36
37PSIM both implements all three levels of the PowerPC and includes (for
38each level) a corresponding simulated run-time environment.
39
40In addition, PSIM, to the execution unit level, models the performance
41of most of the current PowerPC implementations (contributed by Michael
42Meissner). This detailed performance monitoring (unlike many other
43simulators) resulting in only a relatively marginal reduction in the
44simulators performance.
45
46
47A 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
52while an overview of how to use PSIM is in:
53
54 ftp://ftp.ci.com.au/pub/psim/RUN
55or ftp://cambridge.cygnus.com/pub/psim/RUN
56
57This file is found in:
58
59 ftp://ftp.ci.com.au/pub/psim/README
60or ftp://cambridge.cygnus.com/pub/psim/README
61
62
63Thanks goes firstly to:
64
65 Corinthian Engineering Pty Ltd
66 Cygnus Support
67 Highland Logic Pty Ltd
68
69who provided the resources needed for making this software available
70on the Internet.
71
72More importantly I'd like to thank the following individuals who each
73contributed 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
353