Libxml2 Narrowly Avoids Becoming Unmaintained

December 23, 2025 by Maya Posch 3 Comments

In an excellent example of one of the most overused XKCD images, the libxml2 library has for a little while lost its only maintainer, with [Nick Wellnhofer] making good on his plan to step down by the end of the year.

XKCD's dependency model — Modern-day infrastructure, as visualized by XKCD. (Credit: Randall Munroe)

While this might not sound like a big deal, the real scope of this problem is rather profound. Not only is libxml2 part of GNOME, it’s also used as dependency by a huge number of projects, including web browsers and just about anything that processes XML or XSLT. Not having a maintainer in the event that a fresh, high-risk CVE pops up would obviously be less than desirable.

As for why [Nick] stepped down, it’s a long story. It starts in the early 2000s when the original author [Daniel Veillard] decided he no longer had time for the project and left [Nick] in charge. It should be said here that both of them worked as volunteers on the project, for no financial compensation. This when large companies began to use projects like libxml2 in their software, and were happy to send bug reports. Beyond a single Google donation it was effectively unpaid work that required a lot of time spent on researching and processing potential security flaws sent in.

Of note is that when such a security report comes in, the expectation is that you as a volunteer software developer drop everything you’re working on and figure out the cause, fix and patched-by-date alongside filing a CVE. This rather than you getting sent a merge request or similar with an accompanying test case. Obviously these kind of cases seems to have played a major role in making [Nick] burn out on maintaining both libxml2 and libxslt.

Fortunately for the project two new developers have stepped up to take over as maintainers, but it should be obvious that such churn is not a good sign. It also highlights the central problem with the conflicting expectations of open source software being both totally free in a monetary fashion and unburdened with critical bugs. This is unfortunately an issue that doesn’t seem to have an easy solution, with e.g. software bounties resulting in mostly a headache.

Why Chopped Carbon Fiber In FDM Prints Is A Contaminant

December 21, 2025 by Maya Posch 36 Comments

A lot of claims have been made about the purported benefits of adding chopped carbon fiber to FDM filaments, but how many of these claims are actually true? In the case of PLA at least, the [I built a thing] channel on YouTube makes a convincing case that for PLA filament, the presence of chopped CF can be considered a contaminant that weakens the part.

Using the facilities of the University of Basel for its advanced imaging gear, the PLA-CF parts were subjected to both scanning electron microscope (SEM) and Micro CT imaging. The SEM images were performed on the fracture surfaces of parts that were snapped to see what this revealed about the internal structure. From this, it becomes apparent that the chopped fibers distribute themselves both inside and between the layers, with no significant adherence between the PLA polymer and the CF. There is also evidence for voids created by the presence of the CF.

To confirm this, an intact PLA-CF print was scanned using a Micro CT scanner over 13 hours. This confirmed the SEM findings, in that the voids were clearly visible, as was the lack of integration of the CF into the polymer. This latter point shouldn’t be surprising, as the thermal coefficient of PLA is much higher than that of the roughly zero-to-negative of CF. This translates into a cooling PLA part shrinking around the CF, thus creating the voids.

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The ‘Hidden’ Microphone Inside The Sipeed NanoKVM

December 20, 2025 by Maya Posch 42 Comments

Recently, [Jeff Geerling] dropped into the bad press feeding frenzy around Sipeed’s NanoKVM, most notably because of a ‘hidden’ microphone that should have no business on a remote KVM solution. The problem with that reporting is, as [Jeff] points out in the video below, that the NanoKVM – technically the NanoKVM-Cube – is merely a software solution that got put on an existing development board, the LicheeRV Nano, along with an HDMI-in board. The microphone exists on that board and didn’t get removed for the new project, and it is likely that much of the Linux image is also reused.

Of course, the security report that caused so much fuss was published back in February of 2025, and some of the issues pertaining to poor remote security have been addressed since then on the public GitHub repository. While these were valid concerns that should be addressed, the microphone should not be a concern, as it’d require someone to be logged into the device to even use it, at which point you probably have bigger problems.

Security considerations aside, having a microphone in place on a remote KVM solution could also be very useful, as dutifully pointed out in the comments by [bjoern.photography], who notes that being able to listen to beeps on boot could be very useful while troubleshooting a stricken system. We imagine the same is true for other system sounds, such as fan or cooling pump noises. Maybe all remote KVM solutions should have microphone arrays?

Of course, if you don’t like the NanoKVM, you could always roll your own.

Top image: the NanoKVM bundle from [Jeff]’s original review. (Credit: [Jeff Geerling])

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Testing 8 Solder Flux Pastes After Flux Killed A GeForce2 GTS

December 20, 2025 by Maya Posch 16 Comments

Riesba NC-559-ASM flux being applied. (Credit: Bits und Bolts, YouTube)

Flux is one of those things that you cannot really use too much of during soldering, as it is essential for cleaning the surface and keeping oxygen out, but as [Bits und Bolts] recently found, not all flux is made the same. After ordering the same fake Amtech flux from the same AliExpress store, he found that the latest batch didn’t work quite the same, resulting in a Geforce 2 GTS chip getting cooked while trying to reball the chip with uncooperative flux.

Although it’s easy to put this down to a ‘skill issue’, the subsequent test of eight different flux pastes ordered from both AliExpress and Amazon, including — presumably genuine — Mechanic flux pastes with reballing a section of a BGA chip, showed quite different flux characteristics, as you can see in the video below. Although all of these are fairly tacky flux pastes, with some, the solder balls snapped easily into place and gained a nice sheen afterwards, while others formed bridges and left a pockmarked surface that’s indicative of oxygen getting past the flux barrier.

Not all flux pastes are made the same, which also translates into how easy the flux remnants are to clean up. So-called ‘no clean’ flux pastes are popular, which take little more than some IPA to do the cleaning, rather than specialized PCB cleaners as with the used Mechanic flux. Although the results of these findings are up for debate, it can probably be said that ordering clearly faked brand flux paste is a terrible idea. While the top runner brand Riesba probably doesn’t ring any bells, it might be just a Chinese brand name that doesn’t have a Western presence.

As always, caveat emptor, and be sure to read those product datasheets. If your flux product doesn’t come with a datasheet, that would be your first major red flag. Why do we need flux? Find out.

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Reverse-Engineering The Intel 8087 Stack Circuitry

December 19, 2025 by Maya Posch 3 Comments

Although something that’s taken for granted these days, the ability to perform floating-point operations in hardware was, for the longest time, something reserved for people with big wallets. This began to change around the time that Intel released the 8087 FPU coprocessor in 1980, featuring hardware support for floating-point arithmetic at a blistering 50 KFLOPS. Notably, the 8087 uses a stack-based architecture, a major departure from existing FPUs. Recently [Ken Shirriff] took a literal closer look at this stack circuitry to see what it looks like and how it works.

Nearly half of the 8087’s die is taken up by the microcode frontend and bus controller, with a block containing constants like π alongside the FP calculation-processing datapath section taking up much of the rest. Nestled along the side are the eight registers and the stack controller. At 80 bits per FP number, the required registers and related were pretty sizeable for the era, especially when you consider that the roughly 60,000 transistors in the 8087 were paired alongside the 29,000 transistors in the 16-bit 8086.

Each of the 8087’s registers is selected by the decoded instructions via a lot of wiring that can still be fairly easily traced despite the FPU’s die being larger than the CPU it accompanied. As for the unique stack-based register approach, this turned out to be mostly a hindrance, and the reason why the x87 FP instructions in the x86 ISA are still quite maligned today. Yet with careful use, providing a big boost over traditional code, this made it a success by that benchmark, even if MMX, SSE, and others reverted to a stackless design.

Automatically Remove AI Features From Windows 11

December 18, 2025 by Maya Posch 64 Comments

It seems like a fair assessment to state that the many ‘AI’ features that Microsoft added to Windows 11 are at least somewhat controversial. Unsurprisingly, this has led many to wonder about disabling or outright removing these features, with [zoicware]’s ‘Remove Windows AI’ project on GitHub trying to automate this process as much as reasonably possible.

All you need to use it is your Windows 11-afflicted system running at least 25H2 and the PowerShell script. The script is naturally run with Administrator privileges as it has to do some manipulating of the Windows Registry and prevent Windows Update from undoing many of the changes. There is also a GUI for those who prefer to just flick a few switches in a UI instead of running console commands.

Among the things that can be disabled automatically are the disabling of Copilot, Recall, AI Actions, and other integrations in applications like Edge, Paint, etc. The reinstallation of removed packages is inhibited by a custom package. For the ‘features’ that cannot be disabled automatically, there is a list of where to toggle those to ‘off’.

Naturally, since Windows 11 is a moving target, it can be rough to keep a script like this up to date, but it seems to be a good start at least for anyone who finds themselves stuck on Windows 11 with no love for Microsoft’s ‘AI’ adventures. For the other features, there are also Winaero Tweaker and Open-Shell, with the latter in particular bringing back the much more usable Windows 2000-style start menu, free of ads and other nonsense.

Building And Testing A Turbine Driven Hydro Generator

December 18, 2025 by Maya Posch 24 Comments

The theory behind hydropower is very simple: water obeys gravity and imparts the gained kinetic energy onto a turbine, which subsequently drives a generator. The devil here is, of course, in all the details, as [FarmCraft101] on YouTube is in the process of finding out as he adds a small hydro plant to his farm dam. After previously doing all the digging and laying of pipe, in this installment, the goal is to build and test the turbine and generator section so that it can be installed.

The turbine section is 3D-printed and slides onto the metal shaft, which then protrudes from the back where it connects to a 230VAC, three-phase generator. This keeps it quite modular and easy to maintain, which, as it turns out, is a very good idea. After a lot of time spent on the lathe, cutting metal, and tapping threads, the assembled bulk of the system is finally installed for its first test run.

After all that work, the good news is that the 3D-printed turbine seems to work fine and holds up, producing a solid 440 RPM. This put it over the predicted 300 RPM, but that’s where the good news ends. Although the generator produces 28 watts, it’s officially rated for 3 kW at 300 RPM. Obviously, with the small size of this AliExpress-special, the expectation was closer to 750 watts, so that required a bit of investigation. As it turns out, at 300 RPM it only produces 9 watts, so obviously the generator was a dud despite cashing out $230 for it.

Hopefully, all it takes to fix this is to order a new generator to get this hydropower setup up and running. Fortunately, it seems that he’ll be getting his money back from the dud generator, so hopefully in the next video we’ll see the system cranking out something closer to a kilowatt of power.

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