Kernel

Project Description

This project is an educational platform for step-by-step learning and development of basic operating system components. The goal is not to create a fully functional OS, but to understand how its key mechanisms work "from the inside."

RoadMap

• IDT initialization and interrupt handling (CPU exceptions + IRQs).

• PIC remapping and sending EOI.

• PIT (timer) — initialization and handler, incrementing uptime (seconds).

• RTC — reading the current time (accounting for BCD/12h/24h formats, timezone offset).

• VGA console: character output, scrolling, hardware cursor.

• Keyboard handler: scan-code → ASCII, Shift/CapsLock, Backspace, Enter, string input with prompt.

• System call vector (0x80) is already connected in the IDT — framework ready.

• Add a syscall for string output to the terminal (sys_write).

• Memory allocator.

• Add power off and reboot to kernel.

• Multitasking.

• Create terminal.

• Implement a basic file system.

• Make the terminal a separate application rather than part of the kernel.

• Implement Long mode

• Implement working multitasking for Long mode (x86_64)

• Rewrite terminal to (NASM x86_64).

• Check syscall operation (status working)

• Build kernel in iso with GRUB

Iist of available commands:

• htop - prints information about the heap
• clear - clears the terminal
• shutdown (shutdown gives an error in VirtualBox, on all other platforms it works fine (qemu 100% operability)).
• reboot

Build and Run

Build:

make

• All build artifacts (.o files and final binary) are placed in the build/ folder.

• Final binary: build/kernel.

Run in QEMU:

• Regular run (executes build/kernel):

make run

• Debug run with serial (stdout) output — useful for viewing kernel output and entering commands:

make debug

Build with GRUB:

• Make sure you have the necessary tools installed:

sudo apt install grub-pc-bin xorriso mtools

• Compile the project and generate the build/kernel and iso/boot/kernel files:

make

• Use grub-mkrescue to package the kernel into a bootable ISO image:

grub-mkrescue -o kernel.iso iso

• Run the generated ISO using QEMU:

qemu-system-x86_64 -cdrom kernel.iso -m 1024M

Additional QEMU options:

• You can pass options to QEMU via the QEMU_OPTS variable. Examples:

# Run with gdb stub and 512MB RAM
make run QEMU_OPTS="-s -S -m 512"

# debug + gdb
make debug QEMU_OPTS="-s -S"

Note: -s -S enables the gdb stub and halts the CPU until the debugger is attached.

Clean build:

make clean

This will remove build/ and all build artifacts.

Syscall table

Code (rax)	arg1 (rdi)	arg2 (rsi)	arg3 (rdx)	arg4 (r10)	arg5 (r8)	arg6 (r9)	return
(0) print_char_position	char	x	y	fg	bg		0
(1) print_string_position	*str	x	y	fg	bg		0
(2) print_char	char	fg	bg				0
(3) print_string	*str	fg	bg				0
(4) backspace							0
(5) get_time	value	*buf					*prt
(10) malloc	size						*prt
(11) free	*prt						0
(12) realloc	*prt	size					*ptr
(13) get_malloc_stats	*prt						0
(30) get_char							char
(31) set_pos_cursor	x	y					0
(100) power_off
(101) reboot_system
(200) task_create	*str						pid
(201) task_list	*buf	max					quantity
(202) task_stop	pid						status
(203) task_reap_zombies							0
(204) task_exit	exit_code						0
(205) task_is_alive	pid						status