PSIM - model a PowerPC platform Copyright (C) 1994-1995, Andrew Cagney . This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. This directory contains the source code to the program PSIM. What is PSIM? PSIM is an ANSI C program that implements an instruction level model of the PowerPC architecture. It can be configured to model various PowerPC platforms and include: o A user program environment (UEA) complete with emulated system calls to o A hardware platform with several processors interacting with each other and various modeled hardware devices. For each of these models PSIM is able perform a detailed analysis of the machines performance. Who would be interested in PSIM? o the curious Using psim, gdb, gcc and binutils the curious user can contruct an environment that allows them to play with PowerPC user programs with out the need for real hardware. o the analyst PSIM includes many (contributed) monitoring features which (unlike many other simulators) do not come with a great penalty in performance. Thus the performance analyst is able to use this simulator to model the inpact of changes to the system they are analysing. Be that system a compiler or real hardware platform. If PSIM doesn't monitor a components of interest, the source code is freely available, and hence there is no hinderance to changing things to meet a specific analysts needs. o the serious SW developer PSIM models all three levels of the PowerPC Architecture: UEA, VEA and OEA. Further, the internal design is such that PSIM can be extended to suport additional development requirements. Such requirements might include (for the UEA) a new Operating System emulation through to (for the OEA) a model of a different hardware platform. What features does PSIM have? Monitoring and modeling PSIM includes (thanks to Michael Meissner) a detailed model of the various PowerPC implementations schedulers. SMP The PowerPC ISA defines SMP synchronizing instructions this simulator models a limited subset of their behavor. Consequently, if you limit code to the use the modeled behavour, PSIM can be used to model SMP PowerPC platforms. People intending to use this system should study the code implementing the lwarx etc instructions. ENDIAN SUPORT PSIM implements the PowerPC's big and little (xor endian) modes and correctly simulates code that switches between these two modes. In addition, psim can model a true little-endian machine. ISA models (Instruction Set Architecture) PSIM includes a model of the UEA, VEA and OEA. This inclues the time base registers (VEA) and HTAB and BATS (OEA). In addition, a preliminary model of the 64 bit PowerPC architecture is implemented. Hardware PSIM's internals are based around the concept of a Device Tree. This tree intentionaly resembles that of the Device Tree found in OpenBoot firmware. PSIM is flexable enough to allow the user to fully configure the actual hardware model from a device tree specification that is read in from a file. A user can either run a program using one of PSIM's built in hardware models specify a custom hardware model that should be simulated. A user is also able to quickly add a model of new hardware devices so that they can be included in a custom hardware model. OS-Emulation PSIM's UEA model includes emulation for UNIX system calls. PSIM's OEA model includes emulation of either: o OpenBoot client interface o MOTO's BUG interface. Floating point Preliminary suport for floating point is included. What performance analysis measurements can PSIM perform? Below is the output from a recent analysis run (contributed by Michael Meissner): For the following program: long simple_rand () { static unsigned long seed = 47114711; unsigned long this = seed * 1103515245 + 12345; seed = this; return this >> 8; } unsigned long int random_bitstring () { unsigned long int x; int ran, n_bits; int tot_bits = 0; x = 0; for (;;) { ran = simple_rand (); n_bits = (ran >> 1) % 16; tot_bits += n_bits; if (n_bits == 0) return x; else { x <<= n_bits; if (ran & 1) x |= (1 << n_bits) - 1; if (tot_bits > 8 * sizeof (long) + 6) return x; } } } #define ABS(x) ((x) >= 0 ? (x) : -(x)) main () { int i; for (i = 0; i < 50000; i++) { unsigned long x, y; x = random_bitstring (); y = random_bitstring (); if (sizeof (int) == sizeof (long)) goto save_time; { unsigned long xx = x, yy = y, r1, r2; if (yy == 0) continue; r1 = xx / yy; r2 = xx % yy; if (r2 >= yy || r1 * yy + r2 != xx) abort (); } { signed long xx = x, yy = y, r1, r2; if ((unsigned long) xx << 1 == 0 && yy == -1) continue; r1 = xx / yy; r2 = xx % yy; if (ABS (r2) >= (unsigned long) ABS (yy) || (signed long) (r1 * yy + r2) != xx) abort (); } save_time: { unsigned int xx = x, yy = y, r1, r2; if (yy == 0) continue; r1 = xx / yy; r2 = xx % yy; if (r2 >= yy || r1 * yy + r2 != xx) abort (); } { signed int xx = x, yy = y, r1, r2; if ((unsigned int) xx << 1 == 0 && yy == -1) continue; r1 = xx / yy; r2 = xx % yy; if (ABS (r2) >= (unsigned int) ABS (yy) || (signed int) (r1 * yy + r2) != xx) abort (); } { unsigned short xx = x, yy = y, r1, r2; if (yy == 0) continue; r1 = xx / yy; r2 = xx % yy; if (r2 >= yy || r1 * yy + r2 != xx) abort (); } { signed short xx = x, yy = y, r1, r2; r1 = xx / yy; r2 = xx % yy; if (ABS (r2) >= (unsigned short) ABS (yy) || (signed short) (r1 * yy + r2) != xx) abort (); } { unsigned char xx = x, yy = y, r1, r2; if (yy == 0) continue; r1 = xx / yy; r2 = xx % yy; if (r2 >= yy || r1 * yy + r2 != xx) abort (); } { signed char xx = x, yy = y, r1, r2; r1 = xx / yy; r2 = xx % yy; if (ABS (r2) >= (unsigned char) ABS (yy) || (signed char) (r1 * yy + r2) != xx) abort (); } } exit (0); } Here is the current output generated with the -I switch on a 90 Mhz pentium (the compiler used is the devlopment version of GCC with a new scheduler replacing the old one): CPU #1 executed 41,994 AND instructions. CPU #1 executed 519,785 AND Immediate instructions. CPU #1 executed 680,058 Add instructions. CPU #1 executed 41,994 Add Extended instructions. CPU #1 executed 921,916 Add Immediate instructions. CPU #1 executed 221,199 Add Immediate Carrying instructions. CPU #1 executed 943,823 Add Immediate Shifted instructions. CPU #1 executed 471,909 Add to Zero Extended instructions. CPU #1 executed 571,915 Branch instructions. CPU #1 executed 1,992,403 Branch Conditional instructions. CPU #1 executed 571,910 Branch Conditional to Link Register instructions. CPU #1 executed 320,431 Compare instructions. CPU #1 executed 471,911 Compare Immediate instructions. CPU #1 executed 145,867 Compare Logical instructions. CPU #1 executed 442,414 Compare Logical Immediate instructions. CPU #1 executed 1 Condition Register XOR instruction. CPU #1 executed 103,873 Divide Word instructions. CPU #1 executed 104,275 Divide Word Unsigned instructions. CPU #1 executed 132,510 Extend Sign Byte instructions. CPU #1 executed 178,895 Extend Sign Half Word instructions. CPU #1 executed 871,920 Load Word and Zero instructions. CPU #1 executed 41,994 Move From Condition Register instructions. CPU #1 executed 100,005 Move from Special Purpose Register instructions. CPU #1 executed 100,002 Move to Special Purpose Register instructions. CPU #1 executed 804,619 Multiply Low Word instructions. CPU #1 executed 421,201 OR instructions. CPU #1 executed 471,910 OR Immediate instructions. CPU #1 executed 1,292,020 Rotate Left Word Immediate then AND with Mask instructions. CPU #1 executed 663,613 Shift Left Word instructions. CPU #1 executed 1,151,564 Shift Right Algebraic Word Immediate instructions. CPU #1 executed 871,922 Store Word instructions. CPU #1 executed 100,004 Store Word with Update instructions. CPU #1 executed 887,804 Subtract From instructions. CPU #1 executed 83,988 Subtract From Immediate Carrying instructions. CPU #1 executed 1 System Call instruction. CPU #1 executed 207,746 XOR instructions. CPU #1 executed 23,740,856 cycles. CPU #1 executed 10,242,780 stalls waiting for data. CPU #1 executed 1 stall waiting for a function unit. CPU #1 executed 1 stall waiting for serialization. CPU #1 executed 1,757,900 times a writeback slot was unavilable. CPU #1 executed 1,088,135 branches. CPU #1 executed 2,048,093 conditional branches fell through. CPU #1 executed 1,088,135 successful branch predictions. CPU #1 executed 904,268 unsuccessful branch predictions. CPU #1 executed 742,557 branch if the condition is FALSE conditional branches. CPU #1 executed 1,249,846 branch if the condition is TRUE conditional branches. CPU #1 executed 571,910 branch always conditional branches. CPU #1 executed 9,493,653 1st single cycle integer functional unit instructions. CPU #1 executed 1,220,900 2nd single cycle integer functional unit instructions. CPU #1 executed 1,254,768 multiple cycle integer functional unit instructions. CPU #1 executed 1,843,846 load/store functional unit instructions. CPU #1 executed 3,136,229 branch functional unit instructions. CPU #1 executed 16,949,396 instructions that were accounted for in timing info. CPU #1 executed 871,920 data reads. CPU #1 executed 971,926 data writes. CPU #1 executed 221 icache misses. CPU #1 executed 16,949,396 instructions in total. Simulator speed was 250,731 instructions/second What motivated PSIM? As an idea, psim was first discussed seriously during mid 1994. At that time its main objectives were: o good performance Many simulators loose out by only providing a binary interface to the internals. This interface eventually becomes a bottle neck in the simulators performance. It was intended that PSIM would avoid this problem by giving the user access to the full source code. Further, by exploiting the power of modern compilers it was hoped that PSIM would achieve good performance with out having to compromize its internal design. o practical portability Rather than try to be portable to every C compiler on every platform, it was decided that PSIM would restrict its self to suporting ANSI compilers that included the extension of a long long type. GCC is one such compiler, consequenly PSIM should be portable to any machine running GCC. o flexability in its design PSIM should allow the user to select the features required and customize the build accordingly. By having the source code, the compler is able to eliminate any un used features of the simulator. After all, let the compiler do the work. o SMP A model that allowed the simulation of SMP platforms with out the large overhead often encountered with such models. PSIM achieves each of these objectives. Is PSIM PowerPC Platform (PPCP) (nee CHRP) Compliant? No. Among other things it does not have an Apple ROM socket. Can PSIM be configured so that it models a CHRP machine? Yes. PSIM has been designed with the CHRP spec in mind. To model a CHRP desktop a user would need to add the following: o An apple rom socket :-) o Model of each of the desktop IO devices (some may already be implemented). o An OpenPIC (Open Programmable Interrupt Controller) device. (it may by now be implemented). o RTAS (Run Time Abstraction Services). o A fully populated device tree. Is the source code available? Yes. The source code to PSIM is available under the terms of the GNU Public Licence. This allows you to distribute the source code for free but with certain conditions. How do I build PSIM? To build PSIM you will need the following files: gdb-4.15.tar.gz From your favorite GNU ftp site. I've also tested psim with gdb-4.15.1. If you would prefer a graphical development environment then PSIM can also be built with gdbtk. ftp://ftp.ci.com.au/pub/clayton/README.pim This file. ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim.diff.gz Firstly this file contains a few minor changes to gdb-4.15 so that it will build PSIM as part of GDB. ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+note.diff.gz Add suport for note sections (used by OpenBoot PowerPC programs). ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+attach.diff.gz Allow the gdb attach command to work with simulators. ftp://ftp.ci.com.au/pub/clayton/psim-960119.tar.gz This contains the psim files proper. gcc Again available from your favorite GNU ftp site. patch Sun's patch behaves a little wierd and doesn't appear to like creating empty files. You may want to consider installing gnu's patch. Procedure: 0. A starting point $ ls -1 gdb-4.15+attach.diff.gz gdb-4.15+note.diff.gz gdb-4.15+psim.diff.gz gdb-4.15+psim.diff.gz gdb-4.15.tar.gz psim-960119.tar.gz 1. Unpack gdb $ gunzip < gdb-4.15.tar.gz | tar xf - 2. Change to the gdb directory, apply the psim patches and unpack the psim files. $ cd gdb-4.15 $ gunzip < ../gdb-4.15+psim.diff.gz | more $ gunzip < ../gdb-4.15+psim.diff.gz | patch -p1 $ gunzip < ../gdb-4.15+psim-960119.tar.gz | tar tvf - $ gunzip < ../gdb-4.15+psim-960119.tar.gz | tar xvf - You may also want to consider applying the `attach' and `note' patches that are available vis: $ gunzip < ../gdb-4.15+attach.diff.gz | more $ gunzip < ../gdb-4.15+attach.diff.gz | patch -p $ gunzip < ../gdb-4.15+note.diff.gz | more $ gunzip < ../gdb-4.15+note.diff.gz | patch -p 3. Configure gdb $ more gdb/README then something like (I assume SH): $ CC=gcc ./configure --target=powerpc-unknown-eabisim eabisim is needed as by default (because PSIM needs GCC) the simulator is not built. [If building with a more recent gdb snapshot then the command: $CC=gcc ./configure --enable-sim-powerpc is used.] 4. Build $ make CC=gcc alternativly, if you are short on disk space or just want the simulator built: $ ( cd libiberty && make CC=gcc ) $ ( cd bfd && make CC=gcc ) $ ( cd sim/ppc && make CC=gcc ) 5. Install $ make CC=gcc install or just $ cp gdb/gdb ~/bin/powerpc-unknown-eabisim-gdb $ cp sim/ppc/run ~/bin/powerpc-unknown-eabisim-run Is there a more recent version of PSIM and if so, how would I build it? A PSIM is an ongoing development, occasional snapshots (that include new features) are made available. Several of the more recent snapshots are: To build/install one of these snapshots, you replace the current gdb/sim/ppc directory with the one in the update, re-configure and rebuild. Procedure: 0. A starting point $ cd gdb-4.15 1. Remove the old psim directory $ mv sim/ppc sim/old.ppc 2. Unpack the new one $ gunzip < ../psim-960105.tar.gz | tar tf - $ gunzip < ../psim-960105.tar.gz | tar tf - 3. Reconfig/rebuild (as seen above): $ CC=gcc ./configure --target=powerpc-unknown-eabisim $ make CC=gcc Are there any example programs that can be run on PSIM? Psim has a simple test suite that is used to ensure that fixes do not introduce new bugs. This test suite like psim is updated: ftp://ftp.ci.com.au/pub/clayton/psim-test-960118.tar.gz Prebuilt test programs for PSIM. Includes examples of UEA, VEA and OEA code. Requires gcc-2.7.2 and binutils-2.6 to rebuild. How do I use the simulator? I assume that you've unpacked a psim-test archive. 1. As a standalone program Print out the users environment: $ powerpc-unknown-eabisim-run psim-test/uea/envp Print out the arguments: $ powerpc-unknown-eabisim-run psim-test/uea/argv a b c Check that sbrk works: $ powerpc-unknown-eabisim-run psim-test/uea/break 2. Example of running GDB: The main thing to note is that before you can run the simulator you must enable it. The example below illustrates this: $ powerpc-unknown-eabisim-gdb psim-test/uea/envp (gdb) target sim (gdb) load (gdb) break main (gdb) run . . . 3. Using a device tree as a description of a machine (I assume that you have applied the attach bug). $ cd psim-test/tree $ powerpc-unknown-eabisim-gdb (gdb) target sim (gdb) attach device-tree (gdb) run or $ cd psim-test/tree $ powerpc-unknown-eabisim-run device-tree Where do I send bugs or report problems? There is a mailing list (subscribe through majordomo@ci.com.au) (that is almost never used) at: powerpc-psim@ci.com.au If I get the ftp archive updated I post a note to that mailing list. In addition your welcome to send bugs or problems either to me or to that e-mail list. Does PSIM have any limitations or problems? See the file PROBLEMS (included in the distribution) for any outstanding issues. Who helped? Thanks go to the following who each helped in their own way: Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam, Michael Meissner, Bob Mercier, Richard Perini, Dale Rahn Richard Stallman, Mitchele Walker