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hiillos

hiillos is an operating system with its own microkernel all written in pure Zig

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The plan is for the kernel to be just a scheduler, an IPC relay, a physical memory manager and a virtual memory manager.

The system design ~~steals~~ borrows ideas from:

• Zircon: the reference counted capability model
• seL4: synchronous IPC endpoints and asynchronous signals
• RedoxOS: optional filesystem schema (URI protocol here) to reference different services, like fs:///etc/hosts, initfs:///sbin/init, tcp://10.0.0.1:80 or https://archlinux.org

Running in QEMU

zig build run # thats it

# read 'Project-Specific Options' from `zig build --help` for more options
zig build run -Dtest=true # include custom unit test runner

# development cli
zig build run --prominent-compile-errors --summary none \
    # one cpu makes debugging more consistent
    -Dcpus=1 \
    # run the GDB server silently, useful for debugging if the system freezes
    -Dgdb=true \
    # compile faster and with debug info
    -Doptimize=Debug \
    # compile root specifically with higher optimization to speed up initfs decompression
    -Doptimize_root=ReleaseSafe \
    # less initfs compression for faster builds
    -Dzst_l=10

Building an IMG

zig build # generates zig-out/hiillos.img

Stuff included here

• kernel: src/kernel
• kernel/user interface: src/abi
• root process: src/userspace/root

Stuff not included here

• DOOM: xor-bits/hiillos-doomgeneric

IPC performance

Approximate synchronous IPC performance in a call + replyRecv loop:

// server
while (true) {
    msg = try rx.replyRecv(msg);
}
// client
while (true) {
    try tx.call(.{});
}

Full RTT: ~4181 cycles

| | Bare metal | QEMU+KVM | |---------------:|:-----------|:--------------------| | Intel i7-8750H | ? | 481ns (2 078 811Hz) | | Ryzen 9 5950X | ? | 342ns (2 915 712Hz) |

Gallery

<img width="1284" height="832" alt="image" src="https://github.com/user-attachments/assets/d06fa0ee-0bd6-4de0-974f-b77f3d0c226a" /> <img width="1284" height="832" alt="image" src="https://github.com/user-attachments/assets/13414bbb-5b2e-4db0-9fc2-3461f0be58b6" />