This directory contains the source code and documentation of the Nachos instructional operating system. Nachos was designed by the University of Berkeley (see kernel/copyright.h for copyright information). This version of Nachos is a modified version of Nachos made at the university of Rennes. Enhancements compared to the Berkeley Nachos (reverse chronological order): -------------------------------------------------------------------------- - all constants in upper case + consistency in method names (still partial) - embedded documentation through the use of doxygen - reorganisation of the source code - addition of an ACIA device and ACIA device driver - addition of a MMU (linear page tables) - modification of the Nachos statistics module (finer decomposition of the execution time of instructions, management of stats on a per-program basis) - addition of a simplified libc for Nachos (string routines essentially) - addition of a configuration file so that the hardware and software configuration of Nachos can be changed without recompiling it (memory size, initial file system contents, ...) - extension of the file system to support large files and extensible files - new roadmap to Nachos and new assigments (written in french only, but if you have time to translate it in english, feel free to do it) - use of portable code for kernel context switch (using u_contexts) - addition of system calls (thread management, error management) - floating point arithmetic for the MIPS user programs - new process object that aggregates an address space and a set of threads - ELF32 binary file format for the MIPS user programs, instead of noff Directory contents: ------------------- doc: Nachos documentation and assignments (in french) filesys: Nachos filesystem drivers: device drivers (console, disk, ACIA) kernel: Nachos kernel (system calls, multithreading, multiprogramming) machine: Nachos virtual machine (MIPS emulator, MMU, devices) utility: Several utility routines (bitmaps, lists, ...) vm: Virtual memory management userlib: User space (MIPS) basic C library and syscall user interface test: Simple user space (MIPS) test programs Assignments: ----------- Parallelism and synchronization implementation of user-level threads and synchronization tools traps to the operating system Implementation of an ACIA device driver Virtual memory implementation of multiprogramming design of the page fault manager and replacement policy Addition of mapped files to Nachos Parts of the source code was intentionnaly cut at the places that must be designed filled-in the assigments. The complete source code is available on demand (for teachers only :-) Bugs, questions, suggestions for improvements: --------------------------------------------- mail puaut@irisa.fr