https://github.com/dmarro89/go-dav-os
A 32-bit freestanding OS kernel written in Go, booted via GRUB/Multiboot, with VGA terminal, PS/2 keyboard, IDT/PIC/PIT, a debug shell, a bitmap page frame allocator, and an in-memory filesystem
https://github.com/dmarro89/go-dav-os
bare-metal bare-metal-programming go golang grub kernel operating-system operating-system-kernel operating-system-learning operating-systems-project osdev osdev-project osdev-projects qemu
Last synced: 1 day ago
JSON representation
A 32-bit freestanding OS kernel written in Go, booted via GRUB/Multiboot, with VGA terminal, PS/2 keyboard, IDT/PIC/PIT, a debug shell, a bitmap page frame allocator, and an in-memory filesystem
- Host: GitHub
- URL: https://github.com/dmarro89/go-dav-os
- Owner: dmarro89
- License: gpl-3.0
- Created: 2025-12-19T07:41:35.000Z (about 1 month ago)
- Default Branch: main
- Last Pushed: 2026-01-10T21:01:27.000Z (16 days ago)
- Last Synced: 2026-01-11T06:29:21.552Z (15 days ago)
- Topics: bare-metal, bare-metal-programming, go, golang, grub, kernel, operating-system, operating-system-kernel, operating-system-learning, operating-systems-project, osdev, osdev-project, osdev-projects, qemu
- Language: Go
- Homepage:
- Size: 45.9 KB
- Stars: 61
- Watchers: 3
- Forks: 4
- Open Issues: 13
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
README
# go-dav-os
Hobby project to dig deeper into how an OS works by writing the bare essentials of a kernel in Go. Only the kernel lives here (gccgo, x86_64 long mode); BIOS and bootloader are handled by battle-tested tools (GRUB with a Multiboot2 header). No reinvention of those pieces.
## What’s inside
- Boot: `boot/boot.s` exposes the Multiboot2 header and `_start`, sets up a 16 KB stack, enables long mode, and jumps into `kernel.Main`
- The Multiboot2 info pointer is passed to `kernel.Main(...)` in `RDI`
- Freestanding helpers live in `boot/` as well (minimal stubs + `memcmp` to keep the build libc-free)
- Kernel: `kernel/` in Go, freestanding build with gccgo
- IDT + PIC remap + PIT init
- Tick counter from the PIT and a `hlt`-based idle loop when there’s no input
- Terminal: `terminal/` writes to VGA text mode 80x25, manages cursor, scroll, and backspace
- Keyboard: `keyboard/` reads from PS/2 and maps keys with the Italian layout only (temporary)
- Tiny shell: interactive prompt + basic line editing, commands are mostly for debugging
- Memory: `mem/`
- Multiboot2 memory map parsing (`mmap` and `mmapmax` commands)
- A minimal 4KB page frame allocator backed by a bitmap placed inside usable memory (`pfa/alloc/free`)
- Filesystem: `fs/`
- Minimal in-memory FS backed by allocated pages (`ls/write/cat/rm/stat`)
## Architecture
## Project status
- Experimental, single-core
- 64-bit only (x86_64 long mode); 32-bit is no longer supported
- Basic paging (identity map), no real storage drivers yet
- Runs in x86_64 long mode, meant for QEMU/GRUB, no UEFI
- Go runtime pared down: freestanding build (no standard library) with just the stubs the toolchain ends up expecting
## Dependencies
- Via Docker (recommended): Docker with `--platform=linux/amd64`
- Native (if you want to do it manually): cross toolchain `x86_64-elf-{binutils,gccgo}`, `grub-mkrescue`, `xorriso`, `mtools`, `qemu-system-x86_64`
## Build and run (Docker)
```bash
docker build --platform=linux/amd64 -t go-dav-os-toolchain .
docker run --rm --platform=linux/amd64 \
-v "$PWD":/work -w /work go-dav-os-toolchain \
make # builds build/dav-go-os.iso
qemu-system-x86_64 -cdrom build/dav-go-os.iso
```
Quick targets from the Makefile
- `make docker-build-only` builds the image and the ISO
- `make run` (outside Docker) runs QEMU on an existing ISO
## Build natively
Assuming an `x86_64-elf-*` toolchain is installed
```bash
make
qemu-system-x86_64 -cdrom build/dav-go-os.iso
```
To force cross binaries: `make CROSS=x86_64-elf`
## What you’ll see on screen
- On boot the prompt `> ` shows up
- `help` lists commands, `clear` wipes the screen, `about` prints kernel info
- The kernel idles with `hlt` when nothing is happening
### Shell commands (current)
- `help`, `clear`, `about`, `echo`
- `ticks` (PIT tick counter)
- `mem [len]` (hexdump)
- `mmap`, `mmapmax` (Multiboot memory map and highest usable end)
- `pfa`, `alloc`, `free ` (page allocator)
- `ls`, `write `, `cat `, `rm `, `stat ` (filesystem)
- `version` (OS name and version)
## Other folder layout
- `iso/`: GRUB config and ISO packaging bits (grub.cfg)
- `boot/`: also contains the linker script (linker.ld) and a couple of freestanding helpers used by the build
- `build/`: build output (ISO + ELF)
## Contributing
Contributions are welcome! This project is still early-stage and intentionally minimal, so **small PRs** are the best way to help.
- Review [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines
- Check issues labeled [`good first issue`](../../labels/good%20first%20issue) or [`help wanted`](../../labels/help%20wanted)
- Open a [Discussion](../../discussions) to propose an idea or ask a question
## Final note
Personal, open-source, work-in-progress. I’m building pieces as I learn them—the goal is understanding, not chasing modern-OS feature lists
## Contribution
Thanks to:
@metacatdud for taking care of the entire migration from 32 to 64 bit architecture - really amazing work!
@ranjan42 for the useful documentation added and the implementation of the scheduled and the command history
@jgafnea for improving the shell and documenting the contributing section
@soorya38 for taking care of a missing part of the project - the unit tests!