Mirco De Marchi
257 lines
6.2 KiB
Markdown
257 lines
6.2 KiB
Markdown
MentOS
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======
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[](https://forthebadge.com)
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[](https://forthebadge.com)
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[](https://forthebadge.com)
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What is MentOS
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-----------------
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MentOS (Mentoring Operating system) is an open source educational operating
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system.
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The goal of MentOS is to provide a project environment that is realistic
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enough to show how a real Operating System work, yet simple enough that
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students can understand and modify it in significant ways.
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There are so many operating systems, why did we write MentOS?
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It is true, there are a lot of education operating system, BUT
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how many of them follow the guideline de fined by Linux?
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MentOS aims to have the same Linux's data structures and algorithms. It
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has a well-documented source code, and you can compile it on your laptop
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in a few seconds!
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If you are a beginner in Operating-System developing, perhaps MentOS is the
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right operating system to start with.
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Developers
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----------------
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Main Developers:
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* [Enrico Fraccaroli](https://github.com/Galfurian)
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* [Alessandro Danese](https://github.com/alessandroDanese88)
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* [Luigi Capogrosso](https://github.com/luigicapogrosso)
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* [Mirco De Marchi](https://github.com/mircodemarchi)
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Prerequisites
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-----------------
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MentOS is compatible with the main Unix distribution operating systems. It has been tested with *Ubuntu* and *MacOS*, but specifically tested on *Ubuntu 18.04*.
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For compiling the main system:
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* nasm
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* gcc
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* g++
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* make
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* cmake
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* git
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To run and try:
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* qemu-system-i386
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For debugging:
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* ccmake
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* cgdb
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* xterm
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For MacOS, you have additional dependencies:
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* i386-elf-binutils (from [i386-elf-toolchain](https://github.com/nativeos/homebrew-i386-elf-toolchain))
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* i386-elf-gcc (from [i386-elf-toolchain](https://github.com/nativeos/homebrew-i386-elf-toolchain))
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Prerequisites installation commands
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-----------------
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For Ubuntu:
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```
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sudo apt-get update && sudo apt-get upgrade -y
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sudo apt-get install -y build-essential git cmake qemu-system-i386
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sudo apt-get install -y cgdb xterm #<- for debug only
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```
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For MacOS:
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You need to install additionally the i386-elf cross-compiler. The simplest installation method is through Homebrew package manager. Install [Homebrew](https://brew.sh/index_it) if you don't already have and exec the following commands:
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```
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brew update && brew upgrade
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brew tap nativeos/i386-elf-toolchain
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brew install i386-elf-binutils i386-elf-gcc git cmake qemu nasm
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brew install cgdb xterm #<- for debug only
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```
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Compiling MentOS
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-----------------
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Compile and boot MentOS with qemu in Unix systems:
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```
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cd <clone_directory>
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mkdir build
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cd build
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cmake ..
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make
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make qemu
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```
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If you want to access to the shell, use one of the usernames listed in files/passwd.
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**For MacOS**, the steps are the same but instead of `cmake ..`, you have to put an additional argument in order to use the i386-elf cross-compiler:
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```
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cmake -DCMAKE_TOOLCHAIN_FILE=../toolchain.cmake ..
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```
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Change the scheduling algorithm
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-----------------
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MentOS provides three different scheduling algorithms:
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* Round-Robin
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* Priority
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* Completely Fair Scheduling
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If you want to change the scheduling algorithm:
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```
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cd build
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# Round Robin scheduling algorithm
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cmake -DSCHEDULER_TYPE=SCHEDULER_RR ..
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# Priority scheduling algorithm
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cmake -DSCHEDULER_TYPE=SCHEDULER_PRIORITY ..
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# Completely Fair Scheduling algorithm
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cmake -DSCHEDULER_TYPE=SCHEDULER_CFS ..
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make
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make qemu
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```
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Otherwise you can use `ccmake`:
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```
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cd build
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cmake ..
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ccmake ..
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```
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Now you should see something like this:
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```
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BUILD_DOCUMENTATION ON
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CMAKE_BUILD_TYPE
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CMAKE_INSTALL_PREFIX /usr/local
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DEBUGGING_TYPE DEBUG_STDIO
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ENABLE_BUDDY_SYSTEM OFF
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SCHEDULER_TYPE SCHEDULER_RR
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```
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Select SCHEDULER_TYPE, and type Enter to scroll the three available algorithms
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(SCHEDULER_RR, SCHEDULER_PRIORITY, SCHEDULER_CFS).
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Afterwards,
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```
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type c
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type g
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make
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make qemu
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```
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Enable Buddy System
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-----------------
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MentOS provides a Buddy System to manage the allocation and deallocation of
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page frames in physical memory.
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If you want to enable MentOS's Buddy System:
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```
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cd build
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cmake -DENABLE_BUDDY_SYSTEM=ON ..
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make
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make qemu
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```
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Otherwise you can use `ccmake`:
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```
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cd build
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cmake ..
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ccmake ..
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```
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Now you should see something like this:
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```
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BUILD_DOCUMENTATION ON
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CMAKE_BUILD_TYPE
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CMAKE_INSTALL_PREFIX /usr/local
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DEBUGGING_TYPE DEBUG_STDIO
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ENABLE_BUDDY_SYSTEM OFF
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SCHEDULER_TYPE SCHEDULER_RR
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```
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Select ENABLE_BUDDY_SYSTEM, and type Enter.
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You should see something like this:
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```
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BUILD_DOCUMENTATION ON
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CMAKE_BUILD_TYPE
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CMAKE_INSTALL_PREFIX /usr/local
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DEBUGGING_TYPE DEBUG_STDIO
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ENABLE_BUDDY_SYSTEM ON
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SCHEDULER_TYPE SCHEDULER_RR
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```
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Afterwards,
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```
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type c
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type g
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make
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make qemu
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```
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Enable Deadlock Prevention
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-----------------
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MentOS implements the Banker's Algorithm to perform deadlock prevention for
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user-space tasks.
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If you want to enable deadlock prevention in MentOS:
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```
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cd build
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cmake -DENABLE_DEADLOCK_PREVENTION=ON ..
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make
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make qemu
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```
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Otherwise you can use `ccmake` as shown previously for Buddy System enablement.
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You can control the behavior of the deadlock algorithm with a shell command
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line that allows you to run two mis-synchronized processes on two shared
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resources, bringing the operating system into a possible deadlock state.
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Of course the deadlock state is not always reached, because the tasks scheduling
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is nondeterministic. The shell command line is `deadlock [-i <iter>]` where the
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optional parameter `-i <iter>` specify the number of iterations of created tasks
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over the shared resources, by default it will perform only 1 iteration.
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Use Debugger
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-----------------
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If you want to use GDB to debug MentOS:
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```
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cd build
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cmake ..
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make
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make qemu-gdb
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```
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If you did everything correctly, you should have 3 windows with:
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```
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1) - Kernel Booting on qemu
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2) - Shell with video printing of statistics previously discussed
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3) - Debugger cgdb with code screening
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```
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