TangPingOS

TangPingOS is a tiny x86_64 operating system project booted through UEFI with Limine. It is built one verified stage at a time: kernel bring-up, interrupts, memory management, scheduling, user mode, VFS/initrd, shell, and standalone user programs.

Current Status

• Boots on x86_64 UEFI through Limine.
• Prints to the framebuffer and serial console.
• Has GDT/IDT, exception reporting, PIC/PIT IRQs, PS/2 keyboard input, and a preemptive round-robin scheduler.
• Runs Ring 3 ELF user programs with per-process address spaces.
• Loads init.elf as the first process, then starts /bin/shell.elf from initrd.
• Provides devfs, initrd, writable ramfs, file descriptors, dup2, lseek, unlink, spawn, path-based VFS mount dispatch, mount-table queries, and basic system information syscalls.
• Provides a block-device layer with in-memory ramblk0, QEMU virtio-blk vd0, MBR/GPT partition devices such as vd0p1 and vd0p2, an exFAT test mount at /usb with guarded write-path validation builds, a USB Mass Storage exFAT test mount at /usbdisk in QEMU with whitelisted uppercase 8.3 root-file writes, readonly FAT32 boot-partition samples mounted at /boot and /usbboot, and conservative readonly probing for non-QEMU xHCI USB Mass Storage devices with exFAT write-readiness audit plus main/backup boot-region checksum and dry-run write-sector reporting exposed through /usbdisk/info.txt, writeaudit, and a guarded manual writeunlock command that is still off by default for real media.
• Includes an interactive shell plus standalone /bin/hello.elf, /bin/ls.elf, and /bin/cat.elf user programs.

Documentation

See docs/MANUAL.md for:

• User guide and shell command reference.
• Developer guide for writing user programs.
• User-space support library and syscall/API notes.
• Current limitations and real-hardware boot notes.

When a change affects user behavior or the user-space developer API, update the manual in the same change. Internal-only refactors do not need manual updates unless they alter observable behavior.

Build And Run

Install the macOS toolchain:

brew install llvm lld qemu nasm xorriso mtools limine

Build the bootable ISO:

make

Run in QEMU:

make run

Useful targets:

make kernel
make init
make shell
make hello
make ls
make cat
make iso
make clean
make disk
make usb-gpt-disk
make test-exception
make test-page-fault
make test-user-fault
make test-user-programs
make test-exfat-commit

Build outputs:

build/kernel.elf
build/init.elf
build/shell.elf
build/hello.elf
build/ls.elf
build/cat.elf
build/initrd.tar
build/TangPingOS.iso
build/disk.img
build/usb.img

Current startup chain:

kernel -> init.elf -> /bin/shell.elf -> TangPingOS:/>