MentOS (Mentoring Operating system) is an open source educational operating system. The goal of MentOS is to provide a project environment that is realistic enough to show how a real Operating System work, yet simple enough that students can understand and modify it in significant ways.
There are so many operating systems, why did we write MentOS? It is true, there are a lot of education operating system, BUT how many of them follow the guideline de fined by Linux?
MentOS aims to have the same Linux's data structures and algorithms. It has a well-documented source code, and you can compile it on your laptop in a few seconds! If you are a beginner in Operating-System developing, perhaps MentOS is the right operating system to start with.
Main Developers:
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.
For compiling the main system:
- nasm
- gcc
- g++
- make
- cmake
- git
To run and try:
- qemu-system-i386
For debugging:
- ccmake
- cgdb
- xterm
For MacOS, you have additional dependencies:
- i386-elf-binutils (from i386-elf-toolchain)
- i386-elf-gcc (from i386-elf-toolchain)
For Ubuntu:
sudo apt-get update && sudo apt-get upgrade -y
sudo apt-get install -y build-essential git cmake qemu-system-i386
sudo apt-get install -y cgdb xterm #<- for debug only
For MacOS:
You need to install additionally the i386-elf cross-compiler. The simplest installation method is through Homebrew package manager. Install Homebrew if you don't already have and exec the following commands:
brew update && brew upgrade
brew tap nativeos/i386-elf-toolchain
brew install i386-elf-binutils i386-elf-gcc git cmake qemu nasm
brew install cgdb xterm #<- for debug only
Compile and boot MentOS with qemu in Unix systems:
cd <clone_directory>
mkdir build
cd build
cmake ..
make
make qemu
If you want to access to the shell, use one of the usernames listed in files/passwd.
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:
cmake -DCMAKE_TOOLCHAIN_FILE=../toolchain.cmake ..
MentOS provides three different scheduling algorithms:
- Round-Robin
- Priority
- Completely Fair Scheduling
If you want to change the scheduling algorithm:
cd build
# Round Robin scheduling algorithm
cmake -DSCHEDULER_TYPE=SCHEDULER_RR ..
# Priority scheduling algorithm
cmake -DSCHEDULER_TYPE=SCHEDULER_PRIORITY ..
# Completely Fair Scheduling algorithm
cmake -DSCHEDULER_TYPE=SCHEDULER_CFS ..
make
make qemu
Otherwise you can use ccmake:
cd build
cmake ..
ccmake ..
Now you should see something like this:
BUILD_DOCUMENTATION ON
CMAKE_BUILD_TYPE
CMAKE_INSTALL_PREFIX /usr/local
DEBUGGING_TYPE DEBUG_STDIO
ENABLE_BUDDY_SYSTEM OFF
SCHEDULER_TYPE SCHEDULER_RR
Select SCHEDULER_TYPE, and type Enter to scroll the three available algorithms (SCHEDULER_RR, SCHEDULER_PRIORITY, SCHEDULER_CFS). Afterwards,
type c
type g
make
make qemu
MentOS provides a Buddy System to manage the allocation and deallocation of page frames in the physical memory.
If you want to enable the MentOS's Buddy System:
cd build
cmake -DENABLE_BUDDY_SYSTEM=ON ..
make
make qemu
Otherwise you can use ccmake:
cd build
cmake ..
ccmake ..
Now you should see something like this:
BUILD_DOCUMENTATION ON
CMAKE_BUILD_TYPE
CMAKE_INSTALL_PREFIX /usr/local
DEBUGGING_TYPE DEBUG_STDIO
ENABLE_BUDDY_SYSTEM OFF
SCHEDULER_TYPE SCHEDULER_RR
Select ENABLE_BUDDY_SYSTEM, and type Enter. You should see something like this:
BUILD_DOCUMENTATION ON
CMAKE_BUILD_TYPE
CMAKE_INSTALL_PREFIX /usr/local
DEBUGGING_TYPE DEBUG_STDIO
ENABLE_BUDDY_SYSTEM ON
SCHEDULER_TYPE SCHEDULER_RR
Afterwards,
type c
type g
make
make qemu
If you want to use GDB to debug MentOS:
cd build
cmake ..
make
make qemu-gdb
If you did everything correctly, you should have 3 windows with:
1) - Kernel Booting on qemu
2) - Shell with video printing of statistics previously discussed
3) - Debugger cgdb with code screening