thanOS - a modern 64-bit operating system.

Languages & Technology

• C++
• Limine (64-bit bootloader)
• Some assembly

Current status:

• Working shell

• Custom interrupts (user can now input to screen, handle division by zero, etc)

• Physical and virtual memory managers (multi-layer pageing)

• Malloc, new, and delete implementations for memory management

• Custom string and vector implementation

• Read from disk in Fat-32 format

• ELF loader (loads programs from the initrd)

• Userland: ring 3 execution with GDT user segments + TSS

• Syscalls via int 0x80 (write, exit — Linux-compatible numbers)

• Preemptive multitasking: timer-driven round-robin scheduler (mt runs two processes at once)

• Per-process address spaces: every process gets its own page tables (CR3 switch in the scheduler), programs all link at the same virtual address

• Blocking read() syscall: processes sleep waiting for keyboard input (interactive echo program)

• spawn() syscall: a process can launch another process

• Userland shell (ush): a shell running in ring 3, reads input and spawns child programs entirely via syscalls

• wait() syscall: a parent process blocks until its child exits (completes the spawn/wait process model)

Current to-dos:

Robustness (finish the process model) — DONE

• User-fault isolation: a faulting process is killed, the kernel survives (crash command demos it)
• Process reaping: a dead process's pages, tables, and PML4 are freed on exit (mem command shows zero leak)

Foundation for apps

• Growable heap
• Faster, readable timer (PIT ~1000 Hz)
• Keyboard event queue

Projects

• A simple graphical game (snake/pong)
• FAT32 write support (persistence, note app)
• Doom

Multicore (SMP) — in progress

• Phase 1 DONE: boots all cores (Limine MP), per-core TSS + kernel stack, APs park (-smp N → "N cores online")
• Phase 2 DONE: spinlock + interrupt-safe variant (spinlock.h); PMM, heap, scheduler guarded (terminal deferred to Phase 3)
• Phase 3 DONE: full PIC→APIC migration — per-core LAPIC IDs, LAPIC timer scheduling, IOAPIC keyboard (ACPI MADT parse), legacy PIC retired, reentrant terminal lock

• Phase 4: multicore scheduling (unleash the APs — per-core current process, parallel execution)
• Phase 5: lock-free SPSC ring buffer for keyboard input
• Network stack (e1000 -> ARP/ICMP -> UDP/DNS -> TCP -> HTTP)
• FAT32: follow cluster chains (multi-cluster files)
• Doom :)