C4-OS aims to be a relatively complete hobby operating system built around the C4 kernel, which is an L4-like microkernel. Right now, it's composed of a the kernel, a few low-level utility libraries such as the c4 runtime, some PC device drivers, some test programs, and a forth interpreter.

• Multithreading, SMP-capable
• Userland drivers and pagers
• Capability-oriented syscall API
• Syncronous, asyncronous and channel IPC
• Compositing display manager
• Load static ELF executables from disk
• Load and interpret forth programs from disk
• Read and write PATA drives in PIO mode
  • DMA soon lol
• Read from ext2 file systems, incomplete
  • Partial write support, very broken

• Software ports
  • lua, libpng, freetype2, zlib, the usual suspects
  • POSIX compatibility layer
• Networking
  • e1000, r8139, virtio drivers planned
  • port of lwip or uip for the TCP stack
• Graphics
  • Framebuffer multiplexer
  • Fancy window manager and programs for it (console, file manager, etc)
• File systems
  • VFS layer, for providing virtual mount points and caching on top of filesystems
  • FAT driver
• Platforms
  • x86-64 relatively soon
  • support for some ARM-based SBCs (beaglebone, raspberry pi)

• Virtualization
  • Paravirtualization
    • "OS rehosting"
    • based on vCPUs in L4 Fiasco
  • Exposing intel and amd virtualization instruction sets to userland
• support for NetBSD rump kernels, based on work the sel4 folks have done
  • See here

• I like operating systems, became bored of working on my unix clone, and wanted to learn more about microkernels. If you happen to be looking for a production-ready microkernel, take a look at fiasco or sel4.