Goal: write a simple operating system in as few lines as possible.

• Shell with basic commands
• Memory Management
  • Physical memory manager (bitmap allocator)
  • Paging with 4KB pages
  • Kernel heap allocator
• GUI
  • Framebuffer graphics (800x600x32)
  • Window system with dragging, minimize, maximize, close
  • Double-buffered rendering
  • Mouse and keyboard input
  • GNOME-style desktop with top panel and dock
• File System
  • In-memory VFS with directories and files
• Process Management
  • Process control blocks (8 max processes, 32 max threads)
  • Round-robin preemptive scheduler (thread-based)
  • Context switching between threads
  • Per-process page tables (shared by threads)
• User Mode
  • Ring 0/Ring 3 separation
  • 24 syscalls (write, read, exit, fork, exec, wait, pipe, kill, signal, thread_create, thread_join, futex_wait, futex_wake, etc.)
  • TSS for privilege level switching
• IPC
  • Pipes with blocking read/write
  • Signals (SIGINT, SIGKILL, SIGUSR1, SIGUSR2, SIGTERM, SIGCHLD)
  • Per-process file descriptor tables
• Threading
  • Kernel threads (up to 32 system-wide)
  • Thread syscalls (thread_create, thread_exit, thread_join, gettid)
  • Thread-local storage (TLS) support
  • Futex-based synchronization primitives
  • Threads share address space, have separate kernel stacks

• Networking
  • NIC driver
  • TCP/IP stack
  • Sockets API
• Storage
  • ATA/IDE disk driver
  • Persistent filesystem (ext2 or FAT)
  • Exec from filesystem paths
• Virtual Memory
  • Copy-on-write for fork
  • Demand paging
  • Swap space
  • mmap/munmap
  • Shared memory
• Time
  • RTC driver
  • System time (gettimeofday)
  • sleep/alarm syscalls
• I/O
  • dup/dup2 syscalls
  • select/poll
  • waitpid for zombie reaping
• Security
  • Users and groups
  • File permissions
• Multicore
  • SMP support
  • Per-CPU scheduling
• Power
  • ACPI
  • Shutdown/reboot