unfork(2) is the inverse of fork(2). sort of.

By combining userfaultfd with process_vm_readv, any userspace application can obtain a copy-on-write mapping (with some limitations) of memory it never owned. All it needs is ptrace privileges, which is to say, having the same uid usually works.

Ben Rich didn’t build the Stealth because he had no constraints. He built it in spite of the constraints, because he was Ben Rich. If you aren’t managing to “build your stealth fighter”, it’s probably not just because your organization is a bureaucratic nightmare. It’s because you’re not Ben Rich.

source: grugq

DragonFly version 5.6 brings an improved virtual memory system, updates to radeon and ttm, and performance improvements for HAMMER2.

source: Dfly

It may seem odd if you’ve never worked in games, but it’s actually quite common to have to experiment to find the final technical direction. It leaves a lot of amazing stuff ‘on the side’, never released or shared. It was great to have a chance to share some of that work.

source: L

Existing processors limit linear addresses to 48 bits. Chapter 2 describes paging extensions that would relax that limit to 57 linear-address bits.

For some reason, my alarm clock requires that I install an app on my phone. And the app required me to create an account.

I’m going to repeat that: In order to set my alarm clock, I had to create an account with the clock manufacturer.

Kernel signal code is a complex maze, it’s very difficult to introduce non-trivial changes without regressions. Over the past month I worked on covering missing elementary scenarios involving the ptrace(2) API. Part of the new tests were marked as expected to success, however a number of them are expected to fail.

source: vermaden

The simple thing to say about this is that it only happens on Ubuntu 16.04, not on 18.04 or 20.04, and it happens because Ubuntu’s normal /etc/bash.bashrc defines a command_not_found_handle function that winds up running a helper program to produce this ‘did you mean’ report. The helper program comes from the command-not-found package, which is installed because it’s Recommended by ubuntu-standard.

Some of them anyway.

source: grugq

Noise is a framework for building crypto protocols. Noise protocols support mutual and optional authentication, identity hiding, forward secrecy, zero round-trip encryption, and other advanced features.

I thought development of Noise was paused, but there have been some recent updates.

On the questionable security of mobile charge stations.

A Deep Dive Into Docker For Engineers Interested In The Gritty Details.

The last-man-standing videogame has grabbed onto American boyhood, pushing aside other pastimes and hobbies and transforming family dynamics

He got his console back sooner than he thought and not because his grades improved. He was assigned a group homework project with students who had decided to collaborate over their game consoles. His mother realized that Fortnite had become so embedded in the boys’ lives that Max couldn’t even do his homework without it.

Also: https://www.theverge.com/2018/12/21/18152012/fortnite-was-2018s-most-important-social-network

Gefs is a new file system built for Plan 9. It aims to be a crash-safe, corruption-detecting, simple, and fast snapshotting file system, in that order. Gefs achieves these goals by building a traditional 9p file system interface on top of a forest of copy-on-write Bε trees. It doesn’t try to be optimal on all axes, but good enough for daily use.

source: L

Allowing an argument to be passed in seven different ways may be convenient for the programmer writing the call, who can save a few seconds looking up the correct spelling of emailclass_name, but debugging what happens when elaborate and inconsistent arguments are misinterpreted will be eat up the gains many times over. Code is written once, and read many times, so we should be willing to spend more time writing it if it will save trouble reading it again later.

perl, but really all duck languages.

Compared to the other “visionary” writers working at the time – William Gibson, Neal Stephenson – Banks is underappreciated. This is because Gibson and Stephenson in certain ways anticipated the evolution of technology, and considered what the world would look like as transformed by “cyberspace.” Both were crucial in helping us to understand that the real technological revolution occurring in our society was not mechanical, but involved the collection, transmission and processing of information.

Banks, by contrast, imagined a future transformed by the evolution of culture first and foremost, and by technology only secondarily. His insights were, I would contend, more profound. But they are less well appreciated, because the dynamics of culture surround us so completely, and inform our understanding of the world so entirely, that we struggle to find a perspective from which we can observe the long-term trends.

What happens when culture becomes freed from all functional constraints? It seems clear that, in the interplanetary competition that develops, the culture that emerges will be the most virulent, or the most contagious. In other words, “the Culture” will simply be that which is best at reproducing itself, by appealing to the sensibilities and tastes of humanoid life-forms.

source: MR

I’ve been confused about Linux tracing systems for years. There’s strace, and ltrace, kprobes, and tracepoints, and uprobes, and ftrace, and perf, and eBPF,

and how does it all fit together and what does it all MEAN?

source: L

Slides and other materials now up.

More specifically a short intro to the Lua environment in Redis.

Not sure this will ever be cost effective (how low does the price need to be?), but it’s interesting project as a statement.