Notes from kernel hacking in Hare, part 2: multi-threading

I have long promised that Hare would not have multi-threading, and it seems that I have broken that promise. However, I have remained true to the not-invented-here approach which is typical of my style by introducing it only after designing an entire kernel to implement it on top of.1

For some background, Helios is a micro-kernel written in Hare. In addition to the project, the Vulcan system is a small userspace designed to test the kernel.

While I don’t anticipate multi-threaded processes playing a huge role in the complete Ares system in the future, they do have a place. In the long term, I would like to be able...

The Book Of CP-System

CCPS: A CPS-1 SDK

The phrase "open source" (still) matters

In 1988, “Resin Identification Codes” were introduced by the plastic industry. These look exactly like the recycling symbol ♺, which is not trademarked or regulated, except that a number is enclosed within the triangle. These symbols simply identify what kind of plastic was used. The vast majority of plastic is non-recyclable, but has one of these symbols on it to suggest otherwise. This is a deceptive business practice which exploits the consumer’s understanding of the recycling symbol to trick them into buying more plastic products.

The meaning of the term “open source” is broadly understood to be defined by the Open Source Initiative’s Open Source Definition, the “OSD”. Under...

Status update, September 2022

I have COVID-19 and I am halfway through my stockpile of tissues, so I’m gonna keep this status update brief.

In Hare news, I finally put the last pieces into place to make cross compiling as easy as possible. Nothing else particularly world-shattering going on here. I have a bunch of new stuff in my patch queue to review once I’m feeling better, however, including bigint stuff — a big step towards TLS support. Unrelatedly, TLS support seems to be progressing upstream in qbe. (See what I did there?)

powerctl is a small new project I wrote to configure power management states on Linux. I’m pretty pleased with how it turned...

Notes from kernel hacking in Hare, part 1

One of the goals for the Hare programming language is to be able to write kernels, such as my Helios project. Kernels are complex beasts which exist in a somewhat unique problem space and have constraints that many userspace programs are not accustomed to. To illustrate this, I’m going to highlight a scenario where Hare’s low-level types and manual memory management approach shines to enable a difficult use-case.

Helios is a micro-kernel. During system initialization, its job is to load the initial task into memory, prepare the initial set of kernel objects for its use, provide it with information about the system, then jump to userspace and fuck off...

AA tree set

In praise of qemu

qemu is another in a long line of great software started by Fabrice Bellard. It provides virtual machines for a wide variety of software architectures. Combined with KVM, it forms the foundation of nearly all cloud services, and it runs SourceHut in our self-hosted datacenters. Much like Bellard’s ffmpeg revolutionized the multimedia software industry, qemu revolutionized virtualisation.

qemu comes with a large variety of studiously implemented virtual devices, from standard real-world hardware like e1000 network interfaces to accelerated virtual hardware like virtio drives. One can, with the right combination of command line arguments, produce a virtual machine of essentially any configuration, either for testing novel configurations or for running production-ready virtual...

Summary of C/C++ integer rules

powerctl: A small case study in Hare for systems programming

powerctl is a little weekend project I put together to provide a simple tool for managing power states on Linux. I had previously put my laptop into suspend with a basic “echo mem | doas tee /sys/power/state”, but this leaves a lot to be desired. I have to use doas to become root, and it’s annoying to enter my password — not to mention difficult to use in a script or to attach to a key binding. powerctl is the solution: a small 500-line Hare program which provides comprehensive support for managing power states on Linux for non-privileged users.

This little project ended up being a useful case-study...