Panelize PCBs Graphically With Hm-panelizer

May 31, 2022 by Dave Rowntree 14 Comments

When you’re working with PCBs and making single units to knock out in those Chinese fabs, going from layout to manufacturable Gerber files is just a few button presses, no matter what PCB layout tool you prefer. But, once you get into producing sets of PCBs that form a larger system, or are making multiple copies for efficient manufacturing, then you’re not going to get far without delving into the art of PCB panelization. We’ve seen a few options over the years, and here’s yet another one that’s looking quite promising — hm-panelizer by [halfmarble] is a cross platform Python GUI application, which leverages Kivy, so it should run on pretty well on most major platforms without too much hassle. The tool is early in development, so is restricted to handling only straight PCB edges, with horizontal mouse-bites for now, but we’re sure it will quickly grow more general purpose capabilities given time and support.

In an ideal world, open source tools like KiCAD would have a built-in panelizer, but for now we can dream and hm-panelizer might just be good enough for some people. For more choices on panelizing, checkout our guide to making it easy, and just to muddy the waters here’s another way to do it.

Linux And C In The Browser

May 28, 2022 by Al Williams 45 Comments

There was a time when trying to learn to write low-level driver or kernel code was hard. You really needed two machines: one to work with, and one to screw up over and over again until you got it right. These days you can just spin up a virtual machine and roll it back every time you totally screw up. Much easier! We don’t think it is all that practical, but [nsommer] has an interesting post about loading up a C compiler and compiling Linux for a virtual machine. What’s different? Oh, the virtual machine is in your browser.

The v86 CPU emulator runs in the browser and looks like a Pentium III computer with the usual hardware. You might think it is slow and it certainly isn’t going to be fast as a rocket, but it does translate machine code into WebAssembly, so performance isn’t as bad as you might think.

The post goes into detail about how to build and create a simple machine web page that hosts v86. Once you cross-compile the kernel you can boot the machine up virtually. The other interesting part is the addition of tcc which is a pretty capable C compiler and much smaller and faster than the very traditional gcc.

The tcc build is tricky because the normal build process compiles the compiler and then uses the same compiler to build the default libraries. When cross-compiling, this doesn’t work well because the library you want for the host compile is different from the library you want to target for the second pass. You’ll see how to work around that in the post. The post continues to show how to do remote debugging and even gets QEMU into the mix. Debugging inside v86 doesn’t seem to work so far. There are more posts on this topic promised.

Honestly, this is one of those things like teaching a chicken to play checkers. It can be done, there’s little practical value, but it is still something to see. On the other hand, if you spend the weekend working through this, your next Linux porting project ought to seem easy by comparison.

Amazing what you can pull off with WebAssembly. If you need a quick introduction, check this one out from [Ben James].

PSP Turned Robot Remote With Custom Software

May 24, 2022 by Tom Nardi 2 Comments

There’s no question that Sony’s PlayStation Portable (PSP) was an impressive piece of hardware when it was released in 2004, but for all its technical wizardry, it wasn’t able to shake Nintendo’s vice-like grip on the handheld market. Perhaps that explains why we still see so many nostalgia-fueled hacks for Nintendo’s Game Boy and Dual Screen (DS) systems, while PSP hacks tend to be few and far between.

But looking at projects like this one that turn the PSP into a capable robot controller (video, embedded below) we can’t help but wonder if the community has been missing out. Thanks to an open source software development kit for the system, [iketsj] was able to write a WiFi controller program that can be run on any PSP with a homebrew-compatible firmware.

The other side of the equation is a simple robot powered by an ESP8266. To take control of the bot, the user connects their handheld to the WiFi network being offered by the MCU and fires up the controller application from the main menu. It’s all very slick, and the fact that you don’t need to make any modifications to the PSP’s hardware is a huge plus. From the video after the break we get the impression that the remote software is pretty simplistic in its current form, but we imagine the only really limitations are how good you are at writing C code for what by today’s standards would be considered a fairly resource constrained system. We’d love to see that widescreen display lit up and showing live first-person video from the bot’s perspective.

Many of the PSP hack’s we’ve seen over the years have been about repurposing the hardware, or in some cases, replacing the system’s internals with something raspberry flavored. Those projects have certainly been interesting in their own ways, but we really like the idea of being able to push a largely stock system into a new role just by writing some custom code for it.

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Lotus 123 For Linux Is Like A Digital Treasure Hunt

May 23, 2022 by Al Williams 84 Comments

Ever hear of Lotus 123? It is an old spreadsheet program that dominated the early PC market, taking the crown from incumbent Visicalc. [Tavis Ormandy] has managed to get the old software running natively under Linux — quite a feat for software that is around 40 years old and was meant for a different operating system. You can see the results in glorious green text on a black screen in the video below.

If you are a recent convert to Linux, you might not remember what a pain it was “in the old days” to install software. But in this case, it is even worse since the software isn’t even for Linux. The whole adventure started with [Tavis] wanting to find the API kit used to add plugins to Lotus. In theory, you could use it to add modern features to the venerable spreadsheet program.

The $395 software development kit wasn’t very common and there was also a Unix version of Lotus 123, but no one seemed to have a copy of that. [Tavis] eventually found someone who ran a circa-1990 BBS and had the data on tape. Turned out there was a hot copy of the SDK that he was able to use. But he noticed something else in the BBS’s list of files: the long-lost Unix version of Lotus!

An investigation found the installer used TD0 files which took some research. Luckily, a utility exists that can convert these to raw disk images. Inside was a very large object file. Apparently, in the days without dynamic loading, that object would be linked with plug in modules to install them.

The object file had all of its debugging information intact which shed a lot of light on the program’s internal operations. The old executables used COFF format but it is possible to relink it to an ELF file. Of course, it isn’t just that easy. [Tavis] wrote a small program to remove the old-style Unix system calls so they could be rerouted to Linux system calls. Some calls just pass through, but others need some translation due to differences in things like structure layout, sizes, and alignment.

In the end, it all worked but didn’t have a valid license. However, [Tavis] felt like since he did have a license and the software is abandoned, he was within his rights to crack the license check.

We are well-known abusers of spreadsheets around here. Of course, we aren’t the only ones.

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Hack Another ELF On The Stack

May 22, 2022 by Matthew Carlson 3 Comments

[dropbear] recently found herself in a pickle. Dumping some data out of an Android app at a specific point for reverse engineering purposes. While it worked great in the simulator, it was painfully slow on hardware via lldb. The solution was to write a patch and apply it to the ELF file.

Writing the AArch64 assembly to dump the buffer is relatively trivial, but adding it to the existing ELF and repackaging it into a new APK leads to strange errors. The relative offsets into .rodata are now all wrong. For those who don’t routinely interface with the format of ELF files, we have a fantastic resource to take you into the dark depths. But the quick summary version is that sections contain various resources, and you find parts of those resources by relative offsets. The program header describes what type of resources each section contains.

[dropbear] found a NOTE section that just contained some metadata. She created a new section at the end of the file for her custom assembly and modified the header to declare the NOTE section as a LOAD section that pointed at her new section, which would get mapped into memory. All that was left to do was tweak the assembly in the actual code to jump to her new code that dumps. The BSS section was extended by a few bytes so that her program could store its state there.

It’s an impressive technique, and her program for modifying the program header is on her website under a BSD-3 license.

One Coder Is Porting Portal To The Nintendo 64

May 18, 2022 by Lewin Day 10 Comments

When Portal came out in 2007, developers Valve chose not to release the groundbreaking title on an obsolete Nintendo console long out of production. Nobody cared at the time, of course, but [James Lambert] is here to right that wrong. Yes, he’s porting Portal to the N64.

The port, or “demake,” as [James] calls it, has been under construction for some time. The project has posed some challenges: Portal was developed for PCs that were vastly more powerful than the Nintendo 64 of 1996. Thus, initial concerns were that the console wouldn’t be able to handle the physics of the game or render the recursive portal graphics.

However, hard work has paid off. [James] has chipped away, bit by bit, making improvements to his engine all the while. The latest work has the portals rendering nicely, and the companion cube works just the way you’d expect. There’s also a visible portal gun, and the engine can even render 15 recursive layers when looking through mirrored portals. Sixteen was too much.

Of course, there’s still lots to do. There’s no player model yet, and basic animations and sound are lacking. However, the core concept is there, and watching [James] flit through the not-quite-round portals is an absolute delight. Even better, it runs smoothly even on original Nintendo hardware. It’s a feat worthy of commendation.

We had no idea what [James] had in store back when we featured his work creating real-time shadows on N64 hardware. Now we know! Video after the break.

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Things Are Getting Rusty In Kernel Land

May 17, 2022 by Jonathan Bennett 163 Comments

There is gathering momentum around the idea of adding Rust to the Linux kernel. Why exactly is that a big deal, and what does this mean for the rest of us? The Linux kernel has been just C and assembly for its entire lifetime. A big project like the kernel has a great deal of shared tooling around making its languages work, so adding another one is quite an undertaking. There’s also the project culture developed around the language choice. So why exactly are the grey-beards of kernel development even entertaining the idea of adding Rust? To answer in a single line, it’s because C was designed in 1971, to run on the minicomputers at Bell Labs. If you want to shoot yourself in the foot, C will hand you the loaded firearm.

On the other hand, if you want to write a kernel, C is a great language for doing low-level coding. Direct memory access? Yep. Inline assembly? Sure. Runs directly on the metal, with no garbage collection or virtual machines in the way? Absolutely. But all the things that make C great for kernel programming also make C dangerous for kernel programming.

Now I hear your collective keyboards clacking in consternation: “It’s possible to write safe C code!” Yes, yes it is possible. It’s just very easy to mess up, and when you mess up in a kernel, you have security vulnerabilities. There’s also some things that are objectively terrible about C, like undefined behavior. C compilers do their best to do the right thing with cursed code like i++ + i++; or a[i] = i++;. But that’s almost certainly not going to do what you want it to, and even worse, it may sometimes do the right thing.

Rust seems to be gaining popularity. There are some ambitious projects out there, like rewriting coreutils in Rust. Many other standard applications are getting a Rust rewrite. It’s fairly inevitable that the collection of Rust developers started to ask, could we invade the kernel next? This was pitched for a Linux Plumbers Conference, and the mailing list response was cautiously optimistic. If Rust could be added without breaking things, and without losing the very things that makes Rust useful, then yes it would be interesting. Continue reading “Things Are Getting Rusty In Kernel Land” →