Overview

PSIM is a program written in extended ANSI-C that emulates the Instruction Set Architecture of the PowerPC microprocessor family. It is freely available in source code form under the terms of the GNU General Public License (version 2 or later).

The publication The PowerPC Architecture: A specification for a new family of RISC processors describes the PowerPC Instruction Set Architecture has having three levels of compliance:

• UEA - User Instruction Set Architecture "the registers, instructions, storage model, and execution model that are available to all application programs"
• VEA - Virtual Environment Architecture "the features of the architecture that permit application programs to create or modify code, to share data among programs in a multiprocessing system, and to optimize the performance of storage accesses"
• OEA - Operating Environment Architecture "the features of the architecture that permit operating systems to allocate and manage storage, to handle errors encountered by application programs, to support I/O devices, and to provide the other services expected of secure, modern, multiprocessor operating systems"

PSIM, both implements all three levels of the PowerPC Instruction Set Architecture, and includes, for each level, a number of simulated run-time environments:

• UEA PSIM can run static programs compiled for any of the following operating systems:
  • NetBSD
  • Solaris
  • LINIX
• VEA Support for environmental features of the Instruction Set Architecture including:
  • Symetric multi-processing
  • Cache manipulation
  • Time base registers
• OEA Details of the target PowerPC Platform being modeled can be specified including:
  • firmware (Motorola BUG or OpenFirmware)
  • memory and I/O address maps
  • attached devices
  • interrupt controller (OpenPIC) configuration

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.

This document, firstly explains how to build and run PSIM. It then goes on to discuss the details of the internals of this simulator.

The most recent formal release of PSIM is version 2.1. In addition to describing that release of PSIM, this document also describes extensions that have been proposed for a future release of the PSIM Architecture.