121
A toy RTOS inside Super Mario Bros. using emulator save states
They're Mario Bros. for the NES, apparently.
122
Writing a simple windows driver in Rust
The Rust language ecosystem is growing each day, its popularity increasing, and with good reason. It’s the only mainstream language that provides memory and concurrency safety at compile time…
123
A friendly tour of process memory on Linux
A deep dive into how Linux manages process memory, page tables, and virtual address spaces
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How to stop Linux threads cleanly
Stopping a Linux thread is a surprisingly annoying affair. In this post I present common pitfalls and some solutions -- although no truly satisfactory method exists.
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When compilers surprise you
Sometimes compilers can surprise and delight even a jaded old engineer like me
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IPv6 Is Hard
Yesterday I read this toot (German) over on mastodon which starts with “IPv6 is hard.” No it’s not. It’s different. I ran across this multiple times: There is an A and an AAAA-record for a FQDN, but the web server is only reachable via IPv4. You can easily test this with curl $ curl -4 https://github.com -o /dev/null…
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Kernel-hack-drill and exploiting CVE-2024-50264 in the Linux kernel
Some memory corruption bugs are much harder to exploit than others. They can involve race conditions, crash the system, and impose limitations that make a researcher's life difficult. Working with such fragile vulnerabilities demands significant time and effort. CVE-2024-50264 in the Linux kernel is one such hard bug…
128
RIP pthread_cancel
I posted about adding pthread_cancel use in curl about three weeks ago, we released this in curl 8.16.0 and it blew up right in our faces. Now, with #18540 we are ripping it out again. What happened? short recap pthreads define “Cancelation points”, a list of POSIX functions where a pthread may be cancelled. In…
129
The unreasonable effectiveness of fuzzing for porting programs
A simple strategy of having LLMs write fuzz tests and build up a port in topological order seems effective at automating porting from C to Rust.
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The state of SIMD in Rust in 2025
If you’re already familiar with SIMD, the table is all you need. And if you’re not, you will understand the table by the end of the…
131
Understanding Memory Management, Part 1: C
UPDATED: 2025-02-15: Fixed some bugs in the examples and pointed out that you don't usually just want to panic on memory allocation failure.
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Linux Kernel Exploitation: Attack of the Vsock
What started off as casual scrolling through the KernelCTF submissions quickly spiraled into a weeks-long deep dive into a deceptively simple patch - and my first root shell from a Linux kernel exploit!
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Environment variables are a legacy mess: Let's dive deep into them
Programming languages have rapidly evolved in recent years. But in software development, the new often meets the old, and the scaffolding that OS gives for running new processes hasn’t changed much since Unix.
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One Dog vs. the Windows 3.1 Graphics Stack
a bunch of weird and random technical stuff
135
The Alder Lake SHLX Anomaly
Apparently shlx is a “medium latency” (3 cycles) instruction on Alder Lake. My disappointment is immeasurable, and my day is ruined.
136
I want a good parallel computer
The GPU in your computer is about 10 to 100 times more powerful than the CPU, depending on workload. For real-time graphics rendering and machine learning, you are enjoying that power, and doing those workloads on a CPU is not viable. Why aren’t we exploiting that power for other workloads? What prevents a GPU from…
137
Exploring Polymorphism in C: Lessons from Linux and FFmpeg's Code Design (2019)
Learn how Linux/FFmpeg C partial codebase is organized to be extensible and act as if it were meant to have “polymorphism”. Specifically, we’re going to briefly explore how Linux …
138
The Xenon Death Flash: How a Camera Nearly Killed the Raspberry Pi 2
The bizarre story of how taking flash photos could instantly crash the Raspberry Pi 2, the community detective work that solved it, and why this strange bug revealed fundamental flaws in modern chip design.
139
Clock synchronization is a nightmare
Time seems simple. But we engineers lose sleep over something as basic as keeping clocks in sync. Here’s why…
140
Using the most unhinged AVX-512 instruction to make fastest phrase search algo
Disclaimers before we start For those who don’t want to read/don’t care that much, here are the results. I hope after seeing them you are compelled to read. TL;DR: I wrote a super fast phrase search algorithm using AVX-512 and achieved wins up to 1600x the performance of Meilisearch. The source code can be found here…
141
Postgres UUIDv7 and per-back end monotonicity
How Postgres’ v7 UUIDs are made monotonic, and why that’s a great feature.
142
Bare metal printf – C standard library without OS
Guide to implementing a C standard library for bare metal hardware using Newlib, enabling powerful functions like printf and malloc without relying on an operating system. This step-by-step guide demonstrates how to configure and integrate Newlib on RISC-V architecture, showing you how to redirect standard I/O through…
143
Making TRAMP faster
I recently changed jobs and found myself in a position where I would need to do a lot of work on remote machines. Since I am Emacs user, the most common way to do this is using TRAMP (Transparent Remote access, Multiple Protcol). TRAMP is an Emacs package that let’s you treat a remote host like a local system, similar…
144
The Mythical IO-Bound Rails App
When the topic of Rails performance comes up, it is commonplace to hear that the database is the bottleneck, so Rails applications are IO-bound anyway, hence Ruby performance doesn’t matter that much, and all you need is a healthy dose of concurrency to make your service scale. But how true is this in general?
145
Booting 5000 Erlangs on Ampere One 192-core
Underjord is an artisanal consultancy doing consulting in Elixir, Nerves with an accidental speciality in marketing and outreach. If you like the writing you should really try the pro version .
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Fast and cheap bulk storage: using LVM to cache HDDs on SSDs
My attempt to create fast and cheap bulk storage by caching HDDs with SSDs on Linux, using standard lvmcache. Contains an introduction to LVM, RAID, and partitioning.
148
SIMD-friendly algorithms for substring searching (2016)
Popular programming languages provide methods or functions which locate a substring in a given string. In C it is the function strstr , the C++ class std::string has the method find , Python's string has methods pos and index , and so on, so forth. All these APIs were designed for one-shot searches . During past…
149
Unusual circuits in the Intel 386's standard cell logic
I've been studying the standard cell circuitry in the Intel 386 processor recently. The 386, introduced in 1985, was Intel's most complex pr...
150
An epic treatise on error models for systems programming languages
Musings on the representation, propagation and handling of errors in existing programming languages, as well as thoughts on future systems. (15K+ words)