sim/ppc/README

   1
   2
   3                 PSIM 1.0 - Model of the PowerPC Environment
   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.
  28
  29 The PowerPC Architecture is described as having three levels of
  30 compliance:
  31
  32         UEA - User Environment Architecture
  33         VEA - Virtual Environment Architecture
  34         OEA - Operating Environment Architecture
  35
  36 PSIM implements all three levels of the PowerPC architecture and, in
  37 addition, includes (for each level) a corresponding simulated run-time
  38 environment.
  39
  40 In addition, PSIM, to the functional unit level, models the
  41 performance of most of the current PowerPC implementations
  42 (contributed by Michael Meissner).  This detailed performance
  43 monitoring (unlike many other simulators) resulting in only a
  44 relatively marginal reduction in the 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         Highland Logic Pty Ltd
  67         Cygnus Support
  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