My Own Kernel (Zig Edition)

A hobby x86_64 kernel written from scratch in Zig. This is a personal, educational project — I'm building it to learn low-level systems programming, memory management, hardware interfacing, and operating system design using modern tooling.

Initially conceived in C, the project migrated to Zig to leverage modern language features in OS development.

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Screenshots

Current state of the kernel running in QEMU, booting via UEFI with the serial output, printed in stdio

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Project Status

The kernel boots natively via UEFI. The make run target is the primary way to run it.

Implemented

• UEFI Bootloader: Hand-written Zig UEFI app loads kernel.bin and passes a BootInfo struct.
• Physical Memory Manager: 4KB page bitmap allocator with kernel/bitmap memory protection.
• Virtual Memory Manager: Higher-half 4-level paging (offset 0xFFFF800000000000).
• Heap Allocator: Implementation of std.mem.Allocator with a Linked-List.
• GDT: Kernel code/data, user code/data, TSS.
• IDT: Full 256-entry table generated at compile time from assembly stubs.
• PIC (legacy): IRQ remapping (master 0x20, slave 0xA0).
• PIT Timer: Programmable Interval Timer at 1000 Hz.
• Syscall Infrastructure: swapgs/sysretq entry, handlers for exit, yield, sleep.
• Hardware Abstraction Layer (HAL): ACPI (RSDP/XSDT/MADT) parsing and initial APIC topology discovery.
• Symmetric Multiprocessing (SMP): Send wake-up signals for each core.

In Progress

• APIC: Replacing the legacy PIC with the local APIC and I/O APIC for interrupt management.
• Multicore Scheduler: Evolving the task scheduler to handle thread dispatching and context switching across multiple APs (Application Processors) now that SMP is initialized.

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How to Build and Run

Dependencies

Tool	Purpose
Zig 0.15	Primary compiler (managed via zvm)
QEMU	Emulator for testing
OVMF	UEFI firmware (/usr/share/edk2/x64/OVMF.4m.fd)

Important: The project uses Zig 0.15. Install it with zvm install 0.15 && zvm use 0.15.

Makefile Targets

# Build and boot via UEFI (recommended)
make run

# Debug mode (QEMU + GDB stub)
make debug

# Clean build artifacts
make clean

# List discovered Zig sources
make info

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Project Structure

/
├── kernel/
│   ├── arch/x86/        # Architecture-specific code (GDT, IDT, paging, syscall ABI, boot)
│   │   ├── firmware/    # Firmware core (ACPI)
│   │   ├── interrupts/  # PIC, APIC and IDT stubs
│   │   ├── mem/         # Paging, memory layout
│   │   ├── cpu/         # CPU features (GDT, TSS, syscalls)
│   │   └── sys/         # Syscall entry/context
│   ├── boot/            # UEFI bootloader (start.zig) + BootInfo shared struct
│   ├── hal/             # Interface definitions (e.g., TimerSource)
│   ├── mm/              # Memory management (PMM, VMM, heap)
│   ├── proc/            # Process manager
│   ├── sch/             # Scheduler + context switch
│   ├── sys/             # Syscall handlers
│   ├── utils/           # Logger│   
    └── lib/             # Generic library code (I/O, logging helpers)
├── build.zig            # Zig build system (cross-compilation, UEFI target)
├── linker.ld            # Linker script (UEFI boot path)
└── Makefile             # Build automation