sim/ppc/README

   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 2 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, write to the Free Software
  20     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  21
  22
  23     ----------------------------------------------------------------------
  24
  25
  26 PSIM is a program written in extended ANSI-C that implements an
  27 instruction level simulation of the PowerPC environment.  It is freely
  28 available in source code form under the terms of the GNU General
  29 Public License (version 2 or later).
  30
  31 The PowerPC Architecture is described as having three levels of
  32 compliance:
  33
  34         UEA - User Environment Architecture
  35         VEA - Virtual Environment Architecture
  36         OEA - Operating Environment Architecture
  37
  38 PSIM both implements all three levels of the PowerPC and includes (for
  39 each level) a corresponding simulated run-time environment.
  40
  41 In addition, PSIM, to the execution unit level, models the performance
  42 of most of the current PowerPC implementations (contributed by Michael
  43 Meissner).  This detailed performance monitoring (unlike many other
  44 simulators) resulting in only a relatively marginal reduction in the
  45 simulators performance.
  46
  47
  48 A description of how to build PSIM is contained in the file:
  49
  50                 ftp://ftp.ci.com.au/pub/psim/INSTALL
  51         or      ftp://cambridge.cygnus.com/pub/psim/INSTALL
  52
  53 while an overview of how to use PSIM is in:
  54
  55         ftp://ftp.ci.com.au/pub/psim/RUN
  56 or      ftp://cambridge.cygnus.com/pub/psim/RUN
  57
  58 This file is found in:
  59
  60         ftp://ftp.ci.com.au/pub/psim/README
  61 or      ftp://cambridge.cygnus.com/pub/psim/README
  62
  63
  64 Thanks goes firstly to:
  65
  66         Corinthian Engineering Pty Ltd
  67         Cygnus Support
  68         Highland Logic Pty Ltd
  69
  70 who provided the resources needed for making this software available
  71 on the Internet.
  72
  73 More importantly I'd like to thank the following individuals who each
  74 contributed in their own unique way:
  75
  76         Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam,
  77         Michael Meissner, Bob Mercier, Richard Perini, Dale Rahn,
  78         Richard Stallman, Mitchele Walker
  79
  80
  81                                 Andrew Cagney
  82                                 Feb, 1995
  83
  84
  85     ----------------------------------------------------------------------
  86
  87
  88     What features does PSIM include?
  89
  90         Monitoring and modeling
  91
  92                 PSIM includes (thanks to Michael Meissner)
  93                 a detailed model of most of the PowerPC
  94                 implementations to the functional unit level.
  95
  96
  97         SMP
  98
  99                 The PowerPC ISA defines SMP synchronizing instructions.
 100                 This simulator implements a limited, but functional,
 101                 subset of the PowerPC synchronization instructions
 102                 behaviour.  Programs that restrict their synchronization
 103                 primitives to those that work with this functional
 104                 sub-set (eg P() and V()) are able to run on the SMP
 105                 version of PSIM.
 106
 107                 People intending to use this system should study
 108                 the code implementing the lwarx instruction.
 109
 110         ENDIAN SUPPORT
 111
 112                 PSIM implements the PowerPC's big and little (xor
 113                 endian) modes and correctly simulates code that
 114                 switches between these two modes.
 115
 116                 In addition, psim can model a true little-endian
 117                 machine.
 118
 119         ISA (Instruction Set Architecture) models
 120
 121                 PSIM includes a model of the UEA, VEA and OEA.  This
 122                 includes the time base registers (VEA) and HTAB
 123                 and BATS (OEA).
 124
 125                 In addition, a preliminary model of the 64 bit
 126                 PowerPC architecture is implemented.
 127
 128         IO Hardware
 129
 130                 PSIM's internals are based around the concept
 131                 of a Device Tree.  This tree intentionally
 132                 resembles that of the Device Tree found in
 133                 OpenBoot firmware.  PSIM is flexible enough
 134                 to allow the user to fully configure this device
 135                 tree (and consequently the hardware model) at
 136                 run time.
 137
 138         Run-time environments:
 139
 140                 PSIM's UEA model includes emulation for BSD
 141                 based UNIX system calls.
 142
 143                 PSIM's OEA model includes emulation of either:
 144
 145                         o       OpenBoot client interface
 146
 147                         o       MOTO's BUG interface.
 148
 149
 150         Floating point
 151
 152                 Preliminary support for floating point is included.
 153
 154
 155     Who would be interested in PSIM?
 156
 157         o       the curious
 158
 159                 Using psim, gdb, gcc and binutils the curious
 160                 user can construct an environment that allows
 161                 them to play with PowerPC Environment without
 162                 the need for real hardware.
 163
 164
 165         o       the analyst
 166
 167                 PSIM includes many (contributed) monitoring
 168                 features which (unlike many other simulators)
 169                 do not come with a great penalty in performance.
 170
 171                 Thus the performance analyst is able to use
 172                 this simulator to analyse the performance of
 173                 the system under test.
 174
 175                 If PSIM doesn't monitor a components of interest,
 176                 the source code is freely available, and hence
 177                 there is no hinderance to changing things
 178                 to meet a specific analysts needs.
 179
 180
 181         o       the serious SW developer
 182
 183                 PSIM models all three levels of the PowerPC
 184                 Architecture: UEA, VEA and OEA.  Further,
 185                 the internal design is such that PSIM can
 186                 be extended to support additional requirements.
 187
 188
 189     What performance analysis measurements can PSIM perform?
 190
 191         Below is the output from a recent analysis run
 192         (contributed by Michael Meissner):
 193
 194         For the following program:
 195
 196         long
 197         simple_rand ()
 198         {
 199           static unsigned long seed = 47114711;
 200           unsigned long this = seed * 1103515245 + 12345;
 201           seed = this;
 202         /* cut-cut-cut - see the file RUN.psim */
 203         }
 204
 205         Here is the current output generated with the -I switch on a P90
 206         (the compiler used is the development version of GCC with a new
 207         scheduler replacing the old one):
 208
 209         CPU #1 executed     41,994 AND instructions.
 210         CPU #1 executed    519,785 AND Immediate instructions.
 211         .
 212         .
 213         .
 214         CPU #1 executed          1 System Call instruction.
 215         CPU #1 executed    207,746 XOR instructions.
 216
 217         CPU #1 executed 23,740,856 cycles.
 218         CPU #1 executed 10,242,780 stalls waiting for data.
 219         CPU #1 executed          1 stall waiting for a function unit.
 220         .
 221         .
 222         .
 223         CPU #1 executed  3,136,229 branch functional unit instructions.
 224         CPU #1 executed 16,949,396 instructions that were accounted for in timing info.
 225         CPU #1 executed    871,920 data reads.
 226         CPU #1 executed    971,926 data writes.
 227         CPU #1 executed        221 icache misses.
 228         CPU #1 executed 16,949,396 instructions in total.
 229
 230         Simulator speed was 250,731 instructions/second
 231
 232
 233     What motivated PSIM?
 234
 235         As an idea, psim was first discussed seriously during mid
 236         1994.  At that time its main objectives were:
 237
 238
 239                 o       good performance
 240
 241                         Many simulators loose out by only providing
 242                         a binary interface to the internals.  This
 243                         interface eventually becomes a bottle neck
 244                         in the simulators performance.
 245
 246                         It was intended that PSIM would avoid this
 247                         problem by giving the user access to the
 248                         full source code.
 249
 250                         Further, by exploiting the power of modern
 251                         compilers it was hoped that PSIM would achieve
 252                         good performance with out having to compromise
 253                         its internal design.
 254
 255
 256                 o       practical portability
 257
 258                         Rather than try to be portable to every
 259                         C compiler on every platform, it was decided
 260                         that PSIM would restrict its self to supporting
 261                         ANSI compilers that included the extension
 262                         of a long long type.
 263
 264                         GCC is one such compiler, consequently PSIM
 265                         should be portable to any machine running GCC.
 266
 267
 268                 o       flexibility in its design
 269
 270                         PSIM should allow the user to select the
 271                         features required and customise the build
 272                         accordingly.  By having the source code,
 273                         the compiler is able to eliminate any un
 274                         used features of the simulator.
 275
 276                         After all, let the compiler do the work.
 277
 278
 279                 o       SMP
 280
 281                         A model that allowed the simulation of
 282                         SMP platforms with out the large overhead
 283                         often encountered with such models.
 284
 285
 286         PSIM achieves each of these objectives.
 287
 288
 289     Is PSIM PowerPC Platform (PPCP) (nee CHRP) Compliant?
 290
 291         No.
 292
 293         Among other things it does not have an Apple ROM socket.
 294
 295
 296     Could PSIM be extended so that it models a CHRP machine?
 297
 298         Yes.
 299
 300         PSIM has been designed with the CHRP spec in mind. To model
 301         a CHRP desktop the following would need to be added:
 302
 303                 o       An apple ROM socket :-)
 304
 305                 o       Model of each of the desktop IO devices
 306
 307                 o       An OpenPIC device.
 308
 309                 o       RTAS (Run Time Abstraction Services).
 310
 311                 o       A fully populated device tree.
 312
 313
 314     Is the source code available?
 315
 316         Yes.
 317
 318         The source code to PSIM is available under the terms of
 319         the GNU Public Licence.  This allows you to distribute
 320         the source code for free but with certain conditions.
 321
 322         See the file:
 323
 324                 ftp://archie.au/gnu/COPYING
 325
 326         For details of the terms and conditions.
 327
 328
 329     Where do I send bugs or report problems?
 330
 331         There is a mailing list (subscribe through majordomo@ci.com.au) at:
 332
 333         powerpc-psim@ci.com.au
 334
 335         If I get the ftp archive updated I post a note to that mailing list.
 336         In addition your welcome to send bugs or problems either to me or to
 337         that e-mail list.
 338
 339         This list currently averages zero articles a day.
 340
 341
 342      Does PSIM have any limitations or problems?
 343
 344         PSIM can't run rs6000/AIX binaries - At present PSIM can only
 345         simulate static executables.  Since an AIX executable is
 346         never static, PSIM is unable to simulate its execution.
 347
 348         PSIM is still under development - consequently there are going
 349         to be bugs.
 350
 351         See the file BUGS (included in the distribution) for any
 352         other outstanding issues.
 353