PSIM - model of 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 program PSIM that implements a model of a PowerPC platform. PSIM can either be built standalone or as part of the debugger GDB. What is PSIM? PSIM is an ANSI C program that models a PowerPC platform. The platform it implements can vary from: o A user program environment (UEA) complete with emulated system calls to o A hardware platform with several processors interacting with each other and modeled hardware. 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 inteface eventually becomming 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. 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 all of Big-endian, little-endian and PowerPC little endian (XOR endian). ISA models PSIM includes a model of 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 included. 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 taken from a file. PSIM also contains several built in device trees. Emulation PSIM is able (UEA) to emulate UNIX calls based on NetBSD abi through to (preliminary) the ROM rom calls found in common firmware (OpenBoot and BUGAPI). floating point Preliminary suport for floating point is included. Real kernels don't need floating point. Can PSIM model a CHRP a.k.a. PowerPC Platform machine? No. but that is now one of its main objectives. (Did you notice it was written PowerPC Platform instead of PowerPC platform?). How do I build PSIM? To build PSIM you will need the following: gdb-4.15.tar.gz From your favorite GNU ftp site. I've also tested psim-951016 with gdb-4.15.1. ftp://ftp.ci.com.au/pub/clayton/README.pim This file. ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.diff.gz This contains a few minor patches to gdb-4.15 so that will include psim when it is built. ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.tar.gz This contains the psim files propper. ftp://ftp.ci.com.au/pub/clayton/psim-test-951016.tar.gz (Optional) A scattering of pre-compiled programs that run under the simulator. 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. Since PSIM is still being developed, from time to time, to meet a specific analysts needsfurther psim snap shots are occasionally made available. These snapshots may or may not work with GDB-4.15. Several of the more recent snapshots are: ftp://ftp.ci.com.au/pub/clayton/psim-951218.tar.gz Hopefully merges in Michael stuff with mine, adds multiple emulations (OpenBoot and NetBSD), revamps inline stuff, rearanges devices so that phandls and ihandles can be implemented. ftp://ftp.ci.com.au/pub/clayton/psim-951203.tar.gz A good snapshot This includes extensions from Michael Meissner that add monitoring of the PowerPC's register and bus architectures. ftp://ftp.ci.com.au/pub/clayton/psim-test-951218.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. Procedure: 0. A starting point $ ls -1 gdb-4.15+psim-951016.diff.gz gdb-4.15+psim-951016.tar.gz gdb-4.15.tar.gz psim-test-951016.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-951016.diff.gz | more $ gunzip < ../gdb-4.15+psim-951016.diff.gz | patch -p1 $ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar tvf - $ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar xvf - 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. 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 How do I use the simulator? (I assume that you've unpacked the psim-test archive). 1. As a standalone program Print out the users environment: $ powerpc-unknown-eabisim-run envp Print out the arguments: $ powerpc-unknown-eabisim-run argv a b c Check that sbrk works: $ powerpc-unknown-eabisim-run 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 envp (gdb) target sim (gdb) load (gdb) break main (gdb) run . . . 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. Are there any known problems? See the ChangeLog file looking for lines taged with the word FIXME. COREFILE.C: The implementation of corefile.c (defined by corefile.h) isn't the best. It is intended to be functionaly correct rather than fast. One option being considered is to add a data cache to reduce the overhead of the most common case of data read/writes. HTAB (page) code for OEA model untested. Some of the vm code instructions unimplemented. Lacks PowerOpen (a.k.a. XCOFF a.k.a. AIX) and NT startups. The PowerOpen worked until I added the ELF one. Missing VEA system calls. Missing or commented out instructions. 64bit target untested. 64bit host broken. For instance use of scanf "%x", &long long. Event code for pending events from within signal handlers not finished/tested. Better and more devices. PORTABILITY (Notes taken from Michael Meissner): Heavy use of the ## operator - fix using the clasic X/**/Y hack; Use of the signed keyword. In particular, signed char has no analogue in classic C (though most implementations of classic C use signed chars); Use of long long which restricts the target compiler to be GCC. Who helped? Thanks go to the following who each helped in some way. Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam, Michael Meissner, Bob Mercier, Richard Perini, Richard Stallman, Mitchele Walker