It was a calm day on the puppy-linux thinkpad. The CPU was cool, the RAM was operating at double data rate, and a gentle breeze flowed through the chassis as the fan whirred away. A girl wanted to log onto Discord to chat with her friends, but much to her dismay, Discord needed a package update! No matter, such things…
I spent the last three weeks in Seoul, partly visiting family I hadn’t seen in years and partly taking a vacation from my usual work in my usual city in my usual context of life. While I haven’t been able to work much at all, I spent my subway rides and waiting-in-line times reading the Singularity Sky series of…
What every SRE should know about GNU/Linux shell related internals: file descriptors, pipes, terminals, user sessions, process groups and daemons # Last updated: Oct 2025 Contents File descriptor and open file description Pipes Process groups, jobs and sessions Terminals and pseudoterminals Despite the era of…
Is exFAT as fragile as some say?
In most systems, integers are stored using a fixed binary representation. It is common to store integers using 32-bit or 64-bit words. You sometimes need to convert it to a string. For example, the integer 12345 might need to be converted to the five characters '12345'. In an earlier blog post, I presented the simpler…
In other words, the $k$-th element of the output sequence is the sum of the first $k$ elements of the input sequence.
Despite the fact that it is not a 'real' vulnerability, escaping privileged Docker containers is nevertheless pretty funny. And because there will always be people who will come up with reasons or excuses to run a privileged container (even though you really shouldn't), this could really be handy at some point in the…
Using CPU % or Energy values in Activity Monitor appears to show that running code on E cores is less efficient than on P cores. Don’t believe a word of it.
In my previous article I looked at the ways that Rust could be better at pointers. Half of the problems were fundamental issues that affect basically every programming language that lets you mess with pointers directly, and the other half were rust-specific issues. My article also proposed two solutions: for the…
Overall discussion on compilers and IRs (LLVM IR, SPIR-V, and MLIR): why they are in their current manner and how they would evolve
Tracking improvements to Postgres partitioning since 2017. In just five years it’s gone from a non-feature to a very good one.
In C, the length of a string in marked by a 0 byte at the end of the string. Thus to determine the length of the string, one must scan it, looking for the 0 byte. Recent ARM processors have a powerful instruction set (SVE) that is well suited for such problems. It allows you … Continue reading Implementing ‘strlen’…
How to disable heap (dynamic memory allocation) in an embedded application? This article goes into the details of linker files and how to detect dynamic memory allocation.
It's been a while since I've last rewritten my favorite lexical analyzer :-) That post is the last in a series implementing a lexer for the TableGen language in a variety of programming languages, using multiple techniques. The last lexer written, in Go, was very fast indeed - processing 1 MiB of source in about 20…
You're probably reading this page because you've attempted to access some part of my blog (Wandering Thoughts) or CSpace , the wiki thing it's part of. Unfortunately you're using a browser version that my anti-crawler precautions consider suspicious, most often because it's too old (most often this applies to versions…
I occasionally do talks about curl. In these talks I often include a few slides that say something abut curl's coverage and presence on different platforms. Mostly to boast of course, but also to help explain to the audience how curl has manged to reach its ten billion installations. This is current incarnation of…
Almost every week I accidentally get into this logging argument. Here’s the problem: people tend to log different things and call it a best-practice. And I a...
Yes, this is a problem of weak static typing of pure C. Pure C is a great tool for some jobs, but here be dragons , as they say.
Fast compact external SSDs are prone to thermal throttling. This is demonstrated during tests writing 96 files, when transfer rates fell from 2 GB/s to around 700 MB/s.
Computing the CRC-32C of a 4KB buffer on a modern x86 chip can be done as a simple loop around the crc32 instruction:
Modern browsers are some of the most complicated programs ever written. For example, the main Firefox library on my system is over 130Mbytes. Doing 130MB of IO poorly can be quite a performance hit, even with SSDs! :). Few people seem to understand how memory-mapped IO works. There are no pre-canned tools to observe…
There is a common view out there that the QUIC transport protocol (RFC 9000) is just another refinement to the original TCP transport protocol [ 1 ] [ 2 ]. I find it hard to agree with this sentiment, and for me QUIC represents a significant shift in the set of transport capabilities available to applications in terms…
First released on August 12, 1981, MS-DOS became the foundation for business computing for almost two decades. This article details different versions and releases that all stemmed from Gary Kildall's QDOS.
Xe Iaso's personal website.
Where did that memset come from?
Implementing the execution functionality of the shell
How to use Nom to parse binary protocols at the level of individual bits
