Philpax

https://fosdem.org/2026/schedule/event/PA7Z9R-skift/

• cutekit
  • Responsible for building; provides machinery for everything
• karm
  • Freestanding core shared between all components of the OS
  • Inspired by Rust/Go/C# stdlibs
  • Split into two components:
    • Freestanding: doesn't rely on any OS
    • Relies onto an OS
  • Written in Karm-flavoured C++
    • C with lambda, modules, and coroutines
    • No exceptions
    • Rust-like monadic error handling
    • String Clang safety checks - clamped lifetime bounds, etc
    • Unsafe buffer usage checks
  • Entrypoint is async, using C++ modules; hello world example presents a UI
    • Inspired by SwiftUI / Jetpack Compose
  • RPC
    • No IDL, using C++ structures
    • Using C++ reflection capabilities to generate code around the structures
• Bootloader: opstart
  • Simple EFI bootloader, like systemd-boot
  • Has its own boot protocol, called handover, basically a mmap with some attributes
  • Uses the same UI library as the rest of the OS
• Hjert microkernel
  • Pragmatic; not academically pure
  • 4k lines of code, minimalistic
  • Handles or ekernel responsibilities, IPC, minimal object model, etc
  • 25 syscalls
  • Syscall implementation
    • Wrapper for userspace memory that cannot be accessed until unwrapped with a with function
• Strata services
  • Strata component manager is loaded by Hjert as the first process
  • strata-cm then starts strata-init, which then launches sevices
  • strata-device (all device drivers, might be changed later), strata-fs, strata-inputs (HID), strata-shell
  • Applications running on top of all o fthis
• Hideo desktop
  • Custom display protocol; kind of like Wayland, but much simpler
  • Adaptive UI - can scale from a smartphone to a desktop
  • Vector based
  • Subpixel antialiasing
  • Truetype
• Skift has its own browser engine, Vael
  • Not really part of Skift
  • HTML/CSS only, no JS
  • Pretty fast
• Demo: cutekit to boot a QEMU VM
  • Looks pretty full-featured
  • Browser can render a few real websites, or snapshots of them, at least snapshots of them
  • Can run DOOM
  • No GPU acceleration
  • Audio is supported in karm, but not in skift itself
• Because the browser is built atop karm, and karm can run in the bootloader... it is possible to run the browser in the bootloader
• Beyond:
  • virtio support
  • networking
  • on-disk filesystem
  • sound server
  • namespacing
• Question: What architectures does it run on?
  • x86, RISC-V in the future
• Question: Real hardware?
  • It could, but it would be missing peripherals and other things
• Question: Custom window protocol - clientside rendering?
  • Yes. See Doom doesn't have any window decoration
• Question: What security mechanisms does your microkernel support?
  • Only from page-isolated processes
  • Each task has a limited domain
• Question: Does the UI library run on Linux?
  • Yes!