353 lines
9.3 KiB
Text
353 lines
9.3 KiB
Text
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PSIM 1.0.1 - Model of the PowerPC Environments
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Copyright (C) 1994-1996, Andrew Cagney <cagney@highland.com.au>.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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----------------------------------------------------------------------
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PSIM is a program written in extended ANSI-C that implements an
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instruction level simulation of the PowerPC environment. It is freely
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available in source code form under the terms of the GNU General
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Public License (version 3 or later).
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The PowerPC Architecture is described as having three levels of
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compliance:
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UEA - User Environment Architecture
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VEA - Virtual Environment Architecture
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OEA - Operating Environment Architecture
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PSIM both implements all three levels of the PowerPC and includes (for
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each level) a corresponding simulated run-time environment.
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In addition, PSIM, to the execution unit level, models the performance
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of most of the current PowerPC implementations (contributed by Michael
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Meissner). This detailed performance monitoring (unlike many other
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simulators) resulting in only a relatively marginal reduction in the
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simulators performance.
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A description of how to build PSIM is contained in the file:
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ftp://ftp.ci.com.au/pub/psim/INSTALL
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or ftp://cambridge.cygnus.com/pub/psim/INSTALL
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while an overview of how to use PSIM is in:
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ftp://ftp.ci.com.au/pub/psim/RUN
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or ftp://cambridge.cygnus.com/pub/psim/RUN
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This file is found in:
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ftp://ftp.ci.com.au/pub/psim/README
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or ftp://cambridge.cygnus.com/pub/psim/README
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Thanks goes firstly to:
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Corinthian Engineering Pty Ltd
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Cygnus Support
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Highland Logic Pty Ltd
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who provided the resources needed for making this software available
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on the Internet.
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More importantly I'd like to thank the following individuals who each
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contributed in their own unique way:
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Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam,
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Michael Meissner, Bob Mercier, Richard Perini, Dale Rahn,
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Richard Stallman, Mitchele Walker
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Andrew Cagney
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Feb, 1995
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----------------------------------------------------------------------
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What features does PSIM include?
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Monitoring and modeling
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PSIM includes (thanks to Michael Meissner)
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a detailed model of most of the PowerPC
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implementations to the functional unit level.
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SMP
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The PowerPC ISA defines SMP synchronizing instructions.
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This simulator implements a limited, but functional,
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subset of the PowerPC synchronization instructions
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behaviour. Programs that restrict their synchronization
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primitives to those that work with this functional
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sub-set (eg P() and V()) are able to run on the SMP
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version of PSIM.
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People intending to use this system should study
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the code implementing the lwarx instruction.
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ENDIAN SUPPORT
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PSIM implements the PowerPC's big and little (xor
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endian) modes and correctly simulates code that
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switches between these two modes.
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In addition, psim can model a true little-endian
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machine.
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ISA (Instruction Set Architecture) models
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PSIM includes a model of the UEA, VEA and OEA. This
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includes the time base registers (VEA) and HTAB
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and BATS (OEA).
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In addition, a preliminary model of the 64 bit
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PowerPC architecture is implemented.
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IO Hardware
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PSIM's internals are based around the concept
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of a Device Tree. This tree intentionally
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resembles that of the Device Tree found in
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OpenBoot firmware. PSIM is flexible enough
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to allow the user to fully configure this device
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tree (and consequently the hardware model) at
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run time.
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Run-time environments:
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PSIM's UEA model includes emulation for BSD
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based UNIX system calls.
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PSIM's OEA model includes emulation of either:
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o OpenBoot client interface
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o MOTO's BUG interface.
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Floating point
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Preliminary support for floating point is included.
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Who would be interested in PSIM?
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o the curious
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Using psim, gdb, gcc and binutils the curious
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user can construct an environment that allows
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them to play with PowerPC Environment without
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the need for real hardware.
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o the analyst
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PSIM includes many (contributed) monitoring
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features which (unlike many other simulators)
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do not come with a great penalty in performance.
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Thus the performance analyst is able to use
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this simulator to analyse the performance of
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the system under test.
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If PSIM doesn't monitor a components of interest,
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the source code is freely available, and hence
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there is no hinderance to changing things
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to meet a specific analysts needs.
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o the serious SW developer
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PSIM models all three levels of the PowerPC
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Architecture: UEA, VEA and OEA. Further,
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the internal design is such that PSIM can
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be extended to support additional requirements.
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What performance analysis measurements can PSIM perform?
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Below is the output from a recent analysis run
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(contributed by Michael Meissner):
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For the following program:
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long
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simple_rand ()
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{
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static unsigned long seed = 47114711;
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unsigned long this = seed * 1103515245 + 12345;
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seed = this;
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/* cut-cut-cut - see the file RUN.psim */
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}
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Here is the current output generated with the -I switch on a P90
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(the compiler used is the development version of GCC with a new
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scheduler replacing the old one):
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CPU #1 executed 41,994 AND instructions.
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CPU #1 executed 519,785 AND Immediate instructions.
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.
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.
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CPU #1 executed 1 System Call instruction.
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CPU #1 executed 207,746 XOR instructions.
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CPU #1 executed 23,740,856 cycles.
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CPU #1 executed 10,242,780 stalls waiting for data.
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CPU #1 executed 1 stall waiting for a function unit.
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CPU #1 executed 3,136,229 branch functional unit instructions.
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CPU #1 executed 16,949,396 instructions that were accounted for in timing info.
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CPU #1 executed 871,920 data reads.
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CPU #1 executed 971,926 data writes.
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CPU #1 executed 221 icache misses.
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CPU #1 executed 16,949,396 instructions in total.
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Simulator speed was 250,731 instructions/second
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What motivated PSIM?
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As an idea, psim was first discussed seriously during mid
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1994. At that time its main objectives were:
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o good performance
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Many simulators loose out by only providing
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a binary interface to the internals. This
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interface eventually becomes a bottle neck
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in the simulators performance.
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It was intended that PSIM would avoid this
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problem by giving the user access to the
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full source code.
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Further, by exploiting the power of modern
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compilers it was hoped that PSIM would achieve
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good performance with out having to compromise
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its internal design.
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o practical portability
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Rather than try to be portable to every
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C compiler on every platform, it was decided
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that PSIM would restrict its self to supporting
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ANSI compilers that included the extension
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of a long long type.
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GCC is one such compiler, consequently PSIM
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should be portable to any machine running GCC.
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o flexibility in its design
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PSIM should allow the user to select the
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features required and customise the build
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accordingly. By having the source code,
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the compiler is able to eliminate any un
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used features of the simulator.
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After all, let the compiler do the work.
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o SMP
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A model that allowed the simulation of
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SMP platforms with out the large overhead
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often encountered with such models.
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PSIM achieves each of these objectives.
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Is PSIM PowerPC Platform (PPCP) (nee CHRP) Compliant?
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No.
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Among other things it does not have an Apple ROM socket.
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Could PSIM be extended so that it models a CHRP machine?
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Yes.
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PSIM has been designed with the CHRP spec in mind. To model
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a CHRP desktop the following would need to be added:
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o An apple ROM socket :-)
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o Model of each of the desktop IO devices
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o An OpenPIC device.
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o RTAS (Run Time Abstraction Services).
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o A fully populated device tree.
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Is the source code available?
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Yes.
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The source code to PSIM is available under the terms of
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the GNU Public Licence. This allows you to distribute
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the source code for free but with certain conditions.
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See the file:
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ftp://archie.au/gnu/COPYING
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For details of the terms and conditions.
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Where do I send bugs or report problems?
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There is a mailing list (subscribe through majordomo@ci.com.au) at:
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powerpc-psim@ci.com.au
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If I get the ftp archive updated I post a note to that mailing list.
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In addition your welcome to send bugs or problems either to me or to
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that e-mail list.
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This list currently averages zero articles a day.
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Does PSIM have any limitations or problems?
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PSIM can't run rs6000/AIX binaries - At present PSIM can only
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simulate static executables. Since an AIX executable is
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never static, PSIM is unable to simulate its execution.
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PSIM is still under development - consequently there are going
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to be bugs.
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See the file BUGS (included in the distribution) for any
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other outstanding issues.
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