PSIM 1.0.1 - Model of the PowerPC Environments Copyright (C) 1994-1996, 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 3 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, see . ---------------------------------------------------------------------- PSIM is a program written in extended ANSI-C that implements an instruction level simulation of the PowerPC environment. It is freely available in source code form under the terms of the GNU General Public License (version 3 or later). The PowerPC Architecture is described as having three levels of compliance: UEA - User Environment Architecture VEA - Virtual Environment Architecture OEA - Operating Environment Architecture PSIM both implements all three levels of the PowerPC and includes (for each level) a corresponding simulated run-time environment. In addition, PSIM, to the execution unit level, models the performance of most of the current PowerPC implementations (contributed by Michael Meissner). This detailed performance monitoring (unlike many other simulators) resulting in only a relatively marginal reduction in the simulators performance. A description of how to build PSIM is contained in the file: ftp://ftp.ci.com.au/pub/psim/INSTALL or ftp://cambridge.cygnus.com/pub/psim/INSTALL while an overview of how to use PSIM is in: ftp://ftp.ci.com.au/pub/psim/RUN or ftp://cambridge.cygnus.com/pub/psim/RUN This file is found in: ftp://ftp.ci.com.au/pub/psim/README or ftp://cambridge.cygnus.com/pub/psim/README Thanks goes firstly to: Corinthian Engineering Pty Ltd Cygnus Support Highland Logic Pty Ltd who provided the resources needed for making this software available on the Internet. More importantly I'd like to thank the following individuals who each contributed in their own unique way: Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam, Michael Meissner, Bob Mercier, Richard Perini, Dale Rahn, Richard Stallman, Mitchele Walker Andrew Cagney Feb, 1995 ---------------------------------------------------------------------- What features does PSIM include? Monitoring and modeling PSIM includes (thanks to Michael Meissner) a detailed model of most of the PowerPC implementations to the functional unit level. SMP The PowerPC ISA defines SMP synchronizing instructions. This simulator implements a limited, but functional, subset of the PowerPC synchronization instructions behaviour. Programs that restrict their synchronization primitives to those that work with this functional sub-set (eg P() and V()) are able to run on the SMP version of PSIM. People intending to use this system should study the code implementing the lwarx instruction. ENDIAN SUPPORT 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 (Instruction Set Architecture) models PSIM includes a model of the UEA, VEA and OEA. This includes the time base registers (VEA) and HTAB and BATS (OEA). In addition, a preliminary model of the 64 bit PowerPC architecture is implemented. IO Hardware PSIM's internals are based around the concept of a Device Tree. This tree intentionally resembles that of the Device Tree found in OpenBoot firmware. PSIM is flexible enough to allow the user to fully configure this device tree (and consequently the hardware model) at run time. Run-time environments: PSIM's UEA model includes emulation for BSD based UNIX system calls. PSIM's OEA model includes emulation of either: o OpenBoot client interface o MOTO's BUG interface. Floating point Preliminary support for floating point is included. Who would be interested in PSIM? o the curious Using psim, gdb, gcc and binutils the curious user can construct an environment that allows them to play with PowerPC Environment without 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 analyse the performance of the system under test. 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 support additional requirements. 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; /* cut-cut-cut - see the file RUN.psim */ } Here is the current output generated with the -I switch on a P90 (the compiler used is the development 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 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 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 compromise 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 supporting ANSI compilers that included the extension of a long long type. GCC is one such compiler, consequently PSIM should be portable to any machine running GCC. o flexibility in its design PSIM should allow the user to select the features required and customise the build accordingly. By having the source code, the compiler 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. Could PSIM be extended so that it models a CHRP machine? Yes. PSIM has been designed with the CHRP spec in mind. To model a CHRP desktop the following would need to be added: o An apple ROM socket :-) o Model of each of the desktop IO devices o An OpenPIC device. 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. See the file: ftp://archie.au/gnu/COPYING For details of the terms and conditions. Where do I send bugs or report problems? There is a mailing list (subscribe through majordomo@ci.com.au) 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. This list currently averages zero articles a day. Does PSIM have any limitations or problems? PSIM can't run rs6000/AIX binaries - At present PSIM can only simulate static executables. Since an AIX executable is never static, PSIM is unable to simulate its execution. PSIM is still under development - consequently there are going to be bugs. See the file BUGS (included in the distribution) for any other outstanding issues.