sim/ppc/README.psim

   1
   2                         PSIM
   3
   4 Copyright (C) 1994-1995, Andrew Cagney <cagney@highland.com.au>
   5
   6 This directory contains the program PSIM that models the PowerPC(tm -
   7 IBM) architecture.  It can either be run stand alone (psim or run) or
   8 used as part of GDB.
   9
  10
  11 KNOWN FEATURES
  12
  13
  14 SMP: A Symetric Multi-Processor configuration is suported.  This
  15 includes modeling of the PowerPC load word and reserve instructions
  16 (if intending to use this feature you are well advised to read the the
  17 source code for the reservation instructions so that you are aware of
  18 any potential limitations in the model).  The number of processors is
  19 selected during startup.
  20
  21 DUAL-ENDIAN: Both little and big endian models are suported.  The
  22 execution of instruction sequences that switch between the two modes,
  23 however, is not.  The endianess is selected during startup.
  24
  25 UIEA, VEA and OEA: The PowerPC architecture defines three levels of
  26 the PowerPC architecture.  This simulator, to a reasonable degree, is
  27 capable of modeling all three.  That is the User Instruction Set
  28 Architecture, the Virtual Environment Architecture and finally the
  29 Operating Environment Architecture.  The environment is selected
  30 during startup.  The OEA model is still under development.
  31
  32 HARDWARE DEVICE TREE: In the OEA, the model of the target machines
  33 hardware is built from a tree of devices (bit like Open Boot).
  34 Included in this is the ability to model bus hierachies and
  35 runtime-configurable devices (eg PCI).  The device tree used to create
  36 the hardware model is created during startup.  This device tree is
  37 still under development.
  38
  39 VEA SYSTEM CALLS: In user mode, basic system calls (read, write, open,
  40 close ...) are emulated.  Under NetBSD (simply because that is what my
  41 machine at home runs) the list is more extensive.
  42
  43 PEDANTIC VEA MEMORY MODEL: This model implements the break (brk, sbrk)
  44 system calls.  Further, the user model has very strict memory access
  45 controls.  User programs can not assume that they can stray off the
  46 end of valid memory areas.  This model defines valid memory addresses
  47 in strict accordance to the executable and does not page allign their
  48 values.  At first this was a bug but since then has turned up several
  49 problems in user code so it is now described as a feature.
  50
  51 PROFILING: The simulation is able to count the number and type of
  52 instructions issued and the number of loads and stores.  This feature
  53 is still under development.
  54
  55 PERFORMANCE: In its default configuration PSIM is constructed so that
  56 it will compile fast and run slow.  Through the enabling of more
  57 agressive compile options (and the disabling of unwanted features) the
  58 build can be changed to compile slow and run fast.
  59
  60 FLOATING POINT: Preliminary suport for floating point is included.
  61 Real kernels don't need floating point.
  62
  63
  64 BUILDING PSIM:
  65
  66 To build PSIM you will need the following:
  67
  68         gdb-4.15.tar.gz         From your favorite GNU ftp site
  69
  70         ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.diff.gz
  71
  72                                 This contains a few minor patches to
  73                                 gdb-4.15 so that will include psim
  74                                 when it is built.
  75
  76         ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.tar.gz
  77
  78                                 This contains the psim files propper.
  79
  80         ftp://ftp.ci.com.au/pub/clayton/psim-test-951016.tar.gz
  81
  82                                 (Optional) A scattering of pre-compiled
  83                                 programs that run under the simulator.
  84
  85         gcc                     Again available from your favorite
  86                                 GNU ftp site.
  87
  88         patch                   Sun's patch behaves a little wierd
  89                                 and doesn't appear to like creating
  90                                 empty files.
  91
  92
  93 In the directory ftp.ci.com.au:pub/clayton you will also notice files
  94 named psim-NNNNNN.tar.gz.  Those, more recent snapshots, may or may
  95 not work with gdb.
  96
  97
  98 0.      A starting point
  99
 100                 $ ls -1
 101                 gdb-4.15+psim-951016.diff.gz
 102                 gdb-4.15+psim-951016.tar.gz
 103                 gdb-4.15.tar.gz
 104                 psim-test-951016.tar.gz
 105
 106
 107 1.      Unpack gdb
 108
 109                 $ gunzip < gdb-4.15.tar.gz | tar xf -
 110
 111
 112 2.      Change to the gdb directory, apply the psim patches and unpack
 113         the psim files.
 114
 115                 $ cd gdb-4.15
 116
 117                 $ gunzip < ../gdb-4.15+psim-951016.diff.gz | more
 118                 $ gunzip < ../gdb-4.15+psim-951016.diff.gz | patch -p1
 119
 120                 $ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar tvf -
 121                 $ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar xvf -
 122
 123
 124 3.      Configure gdb
 125
 126                 $ more gdb/README
 127
 128         then something like (I assume SH):
 129
 130                 $ CC=gcc ./configure --target=powerpc-unknown-eabisim
 131
 132         eabisim is needed as by default (because PSIM needs GCC) the
 133         simulator is not built.
 134
 135
 136 4.      Build
 137
 138                 $ make CC=gcc
 139
 140         alternativly, if you are short on disk space or just want the
 141         simulator built:
 142
 143                 $ ( cd libiberty && make CC=gcc )
 144                 $ ( cd bfd && make CC=gcc )
 145                 $ ( cd sim/ppc && make CC=gcc )
 146
 147
 148 5.      Install
 149
 150                 $ make CC=gcc install
 151         or just
 152                 $ cp gdb/gdb ~/bin/powerpc-unknown-eabisim-gdb
 153                 $ cp sim/ppc/run ~/bin/powerpc-unknown-eabisim-run
 154
 155
 156 USING THE SIMULATOR:
 157
 158 (I assume that you've unpacked the psim-test archive).
 159
 160 1.      As a standalone program
 161
 162         Print out the users environment:
 163
 164                 $ powerpc-unknown-eabisim-run envp
 165
 166         Print out the arguments:
 167
 168                 $ powerpc-unknown-eabisim-run argv a b c
 169
 170         Check that sbrk works:
 171
 172                 $ powerpc-unknown-eabisim-run break
 173
 174
 175 2.      Example of running GDB:
 176
 177         The main thing to note is that before you can run the simulator
 178         you must enable it.  The example below illustrates this:
 179
 180                 $ powerpc-unknown-eabisim-gdb envp
 181                 (gdb) target sim
 182                 (gdb) load
 183                 (gdb) break main
 184                 (gdb) run
 185                 .
 186                 .
 187                 .
 188
 189
 190 BUGS AND PROBLEMS:
 191
 192 There is a mailing list (subscribe through majordomo@ci.com.au) (that
 193 is almost never used) at:
 194
 195         powerpc-psim@ci.com.au
 196
 197 If I get the ftp archive updated I post a note to that news group.  In
 198 addition your welcome to send bugs or problems either to me or to that
 199 e-mail list.
 200
 201
 202 KNOWN PROBLEMS:
 203
 204 See the ChangeLog file looking for lines taged with the word FIXME.
 205
 206 COREFILE.C: The implementation of corefile.c (defined by corefile.h) isn't the
 207 best.  It is intended to be functionaly correct rather than fast.
 208
 209 HTAB (page) code for OEA model untested.  Some of the vm code
 210 instructions unimplemented.
 211
 212 Flush instruction cache instructions do nothing.  Perhaphs they should
 213 (if there is an instruction cache) flush it.
 214
 215 Lacks PowerOpen (a.k.a. XCOFF a.k.a. AIX) and NT startups.  The
 216 PowerOpen worked until I added the ELF one.
 217
 218 OpenBoot and PR*P interfaces missing.  Open boot could be implemented
 219 by putting special instructions at the address of the OpenBoot
 220 callback functions.  Those instructions could than emulate OpenBoot
 221 behavour.
 222
 223 Missing VEA system calls.
 224
 225 Missing or commented out instructions.
 226
 227 64bit target untested.
 228
 229 64bit host broken.  For instance use of scanf "%x", &long long.
 230
 231 Event code for pending events from within signal handlers not
 232 finished/tested.
 233
 234 Better and more devices.
 235
 236 PORTABILITY (Notes taken from Michael Meissner): Heavy use of the ##
 237 operator - fix using the clasic X/**/Y hack; Use of the signed
 238 keyword.  In particular, signed char has no analogue in classic C
 239 (though most implementations of classic C use signed chars); Use of
 240 long long which restricts the target compiler to be GCC.
 241
 242
 243 THANKS:
 244
 245 Thanks go to the following who each helped in some way.
 246
 247         Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam,
 248         Michael Meissner, Bob Mercier, Richard Perini,
 249         Richard Stallman, Mitchele Walker
 250
 251
 252 ----------------------------------------------------------------
 253
 254
 255 Random notes on performance:
 256
 257
 258 $ cd test
 259 time ../psim count `expr 10000000 / 2`
 260 time ../psim volatile-count `expr 10000000 / 7`
 261
 262 Where 2 and 7 are the number of instructions in the main loop.
 263
 264
 265         611/729 - baseline
 266
 267 Tests:
 268
 269         CFLAGS= -c -O2 -m486 -fomit-frame-pointer
 270
 271         o       different first/second level table/switch combinations
 272
 273                 0 - use a table
 274                 1 - use a simple switch
 275                 2 - use an expanded switch
 276
 277 i486DX4/100 - AMD
 278
 279         1/108/140 - switch=0/0/0,expand=2,inline=2,nia=1,cache=1
 280         1/114/140 - switch=0/0/0,expand=2,inline=2,nia=1,cache=1
 281         1/137/149 - switch=0/0,expand=2,inline=1,nia=1,cache=1
 282         1/144/155 - switch=2/1,expand=2,inline=1,nia=1,cache=1
 283         1/153/159 - switch=2/1,expand=0,inline=1,nia=1,cache=1
 284         1/185/189 - switch=0/0,expand=0,inline=1,nia=1
 285
 286 i486DX2/66
 287
 288         1/572/695 - switch=1/1,expand=0,inline=0
 289         1/579/729 - switch=0/0,expand=0,inline=0
 290         1/570/682 - switch=2/2,expand=0,inline=0
 291         1/431/492 - switch=0/0,expand=0,inline=1,nia=0
 292         1/271/292 - switch=2/1,expand=0,inline=1,nia=0
 293         1/270/316 - switch=2/2,expand=0,inline=1,nia=0
 294         1/271/281 - switch=1/1,expand=0,inline=1,nia=1
 295         1/267/274 - switch=2/1,expand=0,inline=1,nia=1