Nachos Projects Overview and Project 1 TA : 吳哲榮 2010/10/21

Outline What’s Nachos? Why do we use Nachos? Nachos Project Overview Nachos installation Nachos Assignment 1 Reference

What ’ s Nachos? Nachos  Not Another Completely Heuristic Operating System Developed by Tom Anderson and his students at UC, Berkeley. 

What ’ s Nachos? Nachos is an instrumental software that allows students to study and modify a “real” operating system. The only difference between Nachos and a real operating system is that Nachos runs a Unix process, whereas a real operating system runs on a real machine.

What ’ s Nachos? Nachos simulates a MIPS machine (MIPS R2/3000) on the host system (Unix, Linux, etc.) Conceptually, Nachos has two modes of execution, namely, MIPS simulator and Nachos “kernel” Reference : nachos.ps

Why do we use Nachos? For understanding operating system concepts, nothing is better than building an operating system. Nachos is simpler than UNIX. Simulator makes debugging easier.  Deterministic

Nachos Project Overview The project for this course is to build an operating system for scratch. The project contains four phases, corresponding to each of the major pieces of a modern OS.  Multiprogramming  Thread management  File Systems and Virtual Memory  Networking

Nachos Installation Platforms you may use  Unix, Linux, Linux over VMware, or Cygwin. Environment  Checking g++ version g++ -v  Both g or g are ok.  If your current gcc version is 4.x.x version, you should install the gcc version. The gcc version is the watershed.

Nachos Installation Download the gcc source code. The following command is the installing flow. # wget gcc tar.gz # tar zxvf gcc tar.gz # mkdir gcc-build # cd gcc-build/ #../gcc-3.3.3/configure --prefix=/usr/local/gcc enable-threads=posix --disable- checking --enable--long-long --host=i386-redhat-linux --with-system-zlib --enable- languages=c,c++,java # make # make install # export PATH=/usr/local/gcc-3.3.3/bin/:$PATH Add the new gcc path to the current command searching path. # export LD_LIBRARY_PATH=/usr/local/gcc-3.3.3/lib/:$LD_LIBRARY_PATH Add the related library to the current library searching path.

Nachos Installation Get Nachos-4.0  tar.gz tar.gz Get Cross Compiler  decstation.linux-xgcc.tgz Move Cross Compiler to / mv./mips-decstation.linux-xgcc.tgz / Untar Cross Compiler cd / tar zxvf mips-decstation.linux-xgcc.tgz

Nachos Installation Untar Nachos tar zxvf nachos-4.0.tar.gz Make Nachos-4.0 cd./nachos-4.0/code make Test cd./userprog./nachos –e../test/test1./nachos –e../test/test2

Nachos Installation You should see the result of test1

Nachos Installation You should see the result of test2

Some Important Things Nachos arguments  Help./nachos –h  Debugging Mode./nachos –s  Execute files./nachos –e [file_name] Recompilation of modified nachos code cd nachos-4.0/code make clean (optional) make

Nachos Assignment 1 Abstract  The assignment is to support multiprogramming. We give some of the code you need, and you have to complete the system. Try execute two programs at the same time on Nachos cd./userprog./nachos –e../test/test1 –e../test/test2 you should see the following result.

Result of simultaneously execution Total threads number is 2 Thread../test/test1 is executing. Thread../test/test2 is executing. Print integer:9 Print integer:8 Print integer:7 Print integer:20 Print integer:21 Print integer:22 Print integer:23 Print integer:24 Print integer:6 Print integer:7 Print integer:8 Print integer:9 Print integer:10 Print integer:12 Print integer:13 Print integer:14 Print integer:15 Print integer:16 Print integer:17

Result of simultaneously execution Print integer:18 Print integer:19 Print integer:20 Print integer:17 Print integer:18 Print integer:19 Print integer:20 Print integer:21 Print integer:23 Print integer:24 Print integer:25 return value:0 Print integer:26 return value:0 No threads ready or runnable, and no pending interrupts. Assuming the program completed. Machine halting! Ticks: total 800, idle 67, system 120, user 613 Disk I/O: reads 0, writes 0 Console I/O: reads 0, writes 0 Paging: faults 0 Network I/O: packets received 0, sent 0 Why the output result of executing two program simultaneously differs from the result of executing two programs separately?

Why should you do? Trace Nachos  Read *.h and *.cc to understand the whole system and see how it is implemented.  You might use some documentations to help yourself understand the system. A Road Map Through Nachos  Trace for NachoOS-4.0 with GLOBAL 

Hints To know why the result is wrong, you may trace the following files.  nachos-4.0/code/userprog/addrspace.h  nachos-4.0/code/userprog/addrspace.cc  nachos-4.0/code/userprog/userkernel.cc  nachos-4.0/code/machine/translate.h  nachos-4.0/code/machine/translate.cc

Hints You have to modify the Nachos code to achieve the correct result. You may try to modify the following functions  nachos-4.0/code/userprog/addrspace.cc constructor destructor initRegister Load

Assignment Requirements 2 person per team Assignment Report (11/18 on the class)  Prepare a presentation about the following topics: Why the result is not congruent with expected How you modified Nachos to make it support multiprogramming – important code segments Everything you consider important

Hand in your reports. Please compress the following in a.zip.  modified source code(s) with path  presentation power-point  final report your.zip (project1_b _b zip) to TA. Deadline: 2010/11/18 23:59

Grading Policy Progress Report20% Correct Result30% Report50%

Reference Author’s Web Page  Thomas Narten's Nachos Roadmap 