OS

The src/ folder contains all the C code for the operating system, while the boot/ contains the assembly files used for booting. The programs/ directory contains 'user' applications that use the OS. Finally boot_sect.asm and kernel_entry.asm provide the initial entry points for booting and the kernel respectively

Building

Dependencies

This library uses cmake and make for the build process. By default it requires i386-elf-gcc gcc library to compile, though normal gcc can be used with minor modifications to the CMakeLists.txt In order to run the OS, qemu is recommended, and the build system has integrated support for running with qemu-system-i386 To debug the project has facilities for debugging with gdb

Compiling

To compile the kernel run the following commands:

mkdir build && cd build
cmake ..
make all

Running

Either run make run from the build directory you created in the previous step for a quick run or use the qemu-launch.sh script for more options.

The qemu-launch.sh script usage is as follows:

qemu-launch.sh             # No params to simply run the command
qemu-launch.sh monitor     # To launch a monitor server at localhost:1235
                           # This can be accessed with `telnet 127.0.0.1 1235`
qemu-launch.sh gdb         # To launch and wait for a gdb connection
                           # For convenience a `.gdbinit` file is provided
                           # This file will automatically connect
                           # and set some useful debugging breakpoints
                           # NOTE: It may be necessary to change the path to the compiled kernel
qemu-launch.sh <args>      # Forwards the args to qemu

Known Bugs

There is currently a few known bugs that are beyond the current scope of the project:

• If the user input types more characters than fit on the screen and then backspaces them, backspace will work but not display on the screen
• In some cases freeing memory may not have sufficient resources and thus may cause an irrecoverable lock up
• If the stack over flows there will be a triple fault resulting in an OS reset
  • This requires user mode to be fixed, which is future work