Run make to build the project, make run to run it in QEMU, and make clean
to remove built objects. make prep will create myos.iso which is bootable.
make write-usb will overwrite /dev/sdb with this ISO. (Be careful; that drive is
assumed to be a USB.)
To disable graphics, change the graphics_enabled function in kern/graphics.c.
The current status is:
| branch | status | keywords |
|---|---|---|
| lab1 | done | bootloader, mode switching |
| lab2 | done | physical memory allocator, page tables |
| lab3 | done | running user-mode ELF files in an "environment" (process) |
| lab4 | done | preemptive multitasking, COW fork(), IPC |
| lab5 | done | file system and shell |
| lab6 | done | networking |
| graphics | done | graphical user interface |
| hardware | done | running the OS on real hardware |
To provide an overview, here's a summary of my work so far:
- Lab 1 was about getting the kernel running. The BIOS loads a small chunk of code, the bootloader, which is the first kernel code that runs. It runs in 16-bit real mode, so the loader must set up a rudimentary page table, switch to 32-bit protected mode, and load the rest of the kernel.
- Lab 2 was about memory management. We wrote a bootstrap memory allocator and a physical page allocator. We also wrote functions for manipulating page tables, which we used to properly set up the kernel page table.
- Lab 3 involved getting a process to run in user mode. We wrote code which loads an ELF file into the address space of a process. We also initialized the Interrupt Descriptor Table to handle exceptions and traps without the kernel crashing. Finally we wrote the code for handling system calls.
- In lab 4 we made multiple processes work together. We brought up secondary processors and added kernel locking. We wrote a primitive scheduler and implemented preemptive multitasking. We wrote an exokernel-style copy-on-write fork function. Finally we added syscalls for IPC.
- In lab 5 we implemented a file system. We then wrote an FS daemon which performs disk i/o in userland. The daemon uses block caching for efficiency. We also implemented a simple shell for running programs from the disk.
- In lab 6 we connected the OS to the internet by implementing a driver for the e1000 network card. We also wrote a small web server which can serve files from the file system.
- In the graphics lab we implemented OS support for a graphical user interface. We implemented a central display server responsible for rendering applications. We wrote a user-mode graphics library and a PS/2 mouse driver. We also wrote a graphical paint application and a terminal emulator.
- In the hardware lab we made changes to the OS to enable it to run on real hardware.
The report/report.pdf file contains a detailed writeup of this work. The writeups/ directory contains internal writeups made during development.