Architecture
Overview
Current SlopOS subsystem map
SlopOS is a Rust kernel and userland organized around a small trusted core, safe kernel subsystems, and a userland async/runtime layer. These docs describe stable architecture and behavior rather than mirroring every source path.
High-level flow
Limine + OVMF
-> early CPU, memory, interrupt, and service setup
-> platform discovery and device initialization
-> scheduler, memory manager, filesystem, network stack, syscall layer
-> init, shell, compositor, terminal, and appsSubsystems
| Subsystem | Responsibility |
|---|---|
| ABI | Shared structs, constants, syscall surface, SlopRing layout, window and network contracts |
| Trusted core | Unsafe machine interfaces, memory primitives, synchronization, task handles, user-copy |
| Boot | Limine handoff, descriptor tables, exceptions, SMP bring-up, boot ordering |
| Kernel services | Stable bridge between low-level trusted primitives and higher kernel subsystems |
| Memory | Process address spaces, demand paging, COW, memfd, ELF loading, pinned user buffers |
| Scheduler | Task lifecycle, SMP scheduling, sleeps, futexes, trap and IRQ handoff |
| Syscalls | Typed dispatch, process, memory, filesystem, networking, signal, ring, UI, and test handlers |
| Drivers | ACPI, APIC/IOAPIC, HPET, PCI, MSI/MSI-X, VirtIO, PS/2, serial, TTY |
| Filesystem | VFS, ext2, ramfs, devfs, pipes, fd tables, polling |
| Networking | VirtIO net, IPv4, ARP, ICMP, UDP, TCP, DNS, AF_UNIX sockets |
| SlopRing | Shared submission/completion ring, registered buffers, provided buffers, completion delivery |
| Runtime | libc layer, SlopRing wrapper, slopfut executor, process and signal futures |
| Windowing | Display protocol, memfd-backed surfaces, compositor, raw window API, appkit widgets |
| Tests | Kernel and userland tests, KTAP serial output, host parser, JSONL reporting |
| Verification | OSTD trusted core, Verus proofs, KernMiri, framekernel discipline gates |
Design lines
- Kernel async is banned. The kernel blocks through synchronous wait queues;
async is a userland edge built on SlopRing and
slopfut. - IRQ and device work use APIC, IOAPIC, MSI/MSI-X, HPET, and VirtIO. PIT exists only as a legacy calibration fallback, not as the scheduler timer.
- The ABI source is generated from the source repo, not from prose in these docs. Reference pages describe shape and semantics; exact numeric assignments belong in the ABI source.
- Tests are ABI consumers: kernel tests, userland tests, KTAP output, and the host parser all exercise public contracts.