A very simple operating system that just boots up very quickly and hence fastos. This is a bare bone kernel which only knows how to write stuffs to video memory. If you want to know how things work, it may be a good to have a look at code.
| File(s) | What it does ? |
|---|---|
isodir |
This contains the kernel and the grub configuration. This section is used to build the iso using grub-mkrescue |
objects |
This directory has two objects. Each compiled from boot.s and kernel.c. The linker links the two to produce our kernel. |
boot.s |
It Assembly Code well documented. This will be invoked by BIOS on startup and its job is to load the high level kernel and do some initializations. |
build.sh |
A script that builds the kernel image and outputs fastos.bin, it is the kernel as ELF binary. |
fastos.bin |
The Kernel itself. |
fastos.iso |
A CD-ROM bootable iso that can boot with GRUB 2. It contains the kernel and grub configuration. It will be build by the contents inside of isodir. |
grub.cnf |
The Grub config file that adds the entry for the OS to boot. |
kernel.c |
This is the kernel source itself. |
linker.ld |
This is the linker script. It will link the two objects in /objects to produce fastos.bin (the kernel). |
make-iso.sh |
This script makes the iso using the contents of isodir |
multiboot-sanity.sh |
This is a simple script that checks if the kernel is multibootable by the grub or not. It must be bootable |
run.sh and run_iso.sh |
This runs the kernel in qemu-system-i386 emulator. ISO or non iso whichever you prefer. |
In order to boot the os you can either make a bootable cdrom using the iso or you can boot the kernel directly on a qemu-system-i386 by running the run.sh . Make sure you have the qemu emulator installed.
Grub Boot Screen.
Information VGA Display
Building an OS requires a cross-compiler. The one that is provided by your OS will run but is likely to throw many error which will be difficult to debug. In order to compile the codes you need to build gcc-7.3.0 and binutils-2.3 that targets i686-elf . Google on how to build cross-compilers and then use those compilers to run the following scripts. (Make sure to add the new gcc and binutils to path). You can read this in order to learn how to build the cross-compiler from source https://wiki.osdev.org/GCC_Cross-Compiler
build.sh: To build the kernelmultiboot-sanity.sh: It must return, "Multibootable OS"make-iso: To build the ISO
Any hacks that you want to do you can do it on kernel.c and it will be good to not mess the file you don't have any idea. This kernel.c cannot include stuffs like stdio.h or other system header. Our OS does not provide these headers as of now.
Special Thanks to https://wiki.osdev.org/Expanded_Main_Page for their great documentations and resources