Linux Fu: The Chrome OS Flex Virtualization

August 10, 2022 by Al Williams 50 Comments

The Flex Desktop is user-friendly and responsive

You’ve probably heard about Google Chromebooks. Like Android, Chrome OS is based on some variant of Linux, but it is targeted at the “cloud first” strategy so Chromebooks typically don’t have a huge amount of storage or compute power. If you have a real Chromebook, you can also use it to run certain other kinds of programs via virtualization. However, Google has recently pushed out Chrome OS Flex which is meant to install on a spare laptop you might happen to have hanging around. Seems attractive to take that only Windows 7 laptop and repurpose it to run Chrome OS, especially if you can run Linux apps on it. Unfortunately, Chrome OS Flex has a very different use case and I would only recommend installing it if you meet the exact use case it addresses.

The other option, of course, is to just install Linux on that old hardware. There are several distributions that are made for that purpose and, honestly, even most of the major distributions will work fine on older hardware with a little tweaking to turn off some of the more resource-costly features. That assumes you know how to install, tweak, and maintain Linux.

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Compare PDFs Visually

August 6, 2022 by Al Williams 12 Comments

Sometimes a problem seems hard, but the right insight can make it easy. If you were asked to write a program to compare two PDF files and show the differences, how hard do you think that would be? If you are [serhack], you’ll make it much easier than you might guess.

Of course, sometimes making something simple depends on making simplifying assumptions. If you are expecting a “diff-like” utility that shows insertion and deletions, that’s not what’s going on here. Instead, you’ll see an image of the PDF with changes highlighted with a red box. This is easy because the program uses available utilities to render the PDFs as images and then simply compares pixels in the resulting images, drawing red boxes over the parts that don’t match.

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Converting An 80s Typewriter Into A Linux Terminal

August 4, 2022 by Dan Maloney 26 Comments

Typewriters may be long past their heyday, but just because PCs, word processor software, and cheap printers have made them largely obsolete doesn’t mean the world is better off without them. Using a typewriter is a rich sensory experience, from the feel of the keys under your fingers that even the clickiest of PC keyboards can’t compare with, to the weirdly universal sound of the type hitting paper.

So if life hands you a typewriter, why not put it back to work? That’s exactly what [Artillect] did by converting an 80s typewriter into a Linux terminal. The typewriter is a Brother AX-25, one of those electronic typewriters that predated word processing software and had a daisy wheel printhead, a small LCD display, and a whopping 8k of memory for editing documents. [Artillect] started his build by figuring out which keys mapped to which characters in the typewriter’s 8×11 matrix, and then turning an Arduino and two multiplexers loose on the driving the print head. The typewriter’s keyboard is yet used for input, as the project is still very much in the prototyping phase, so a Raspberry Pi acts as a serial monitor between the typewriter and a laptop. The video below has a good overview of the wiring and the software, and shows the typewriter banging out Linux command line output.

For now, [Artillect]’s typewriter acts basically like an old-school teletype. There’s plenty of room to take this further; we’d love to see this turned into a cyberdeck complete with a built-in printer, for instance. But even just as a proof of concept, this is pretty great, and you can be sure we’ll be trolling the thrift stores and yard sales looking for old typewriters.

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Photo of the head unit , with "Hacked by greenluigi1" in the center of the UI

Hacker Liberates Hyundai Head Unit, Writes Custom Apps

July 18, 2022 by Arya Voronova 39 Comments

[greenluigi1] bought a Hyundai Ioniq car, and then, to our astonishment, absolutely demolished the Linux-based head unit firmware. By that, we mean that he bypassed all of the firmware update authentication mechanisms, reverse-engineered the firmware updates, and created subversive update files that gave him a root shell on his own unit. Then, he reverse-engineered the app framework running the dash and created his own app. Not just for show – after hooking into the APIs available to the dash and accessible through header files, he was able to monitor car state from his app, and even lock/unlock doors. In the end, the dash got completely conquered – and he even wrote a tutorial showing how anyone can compile their own apps for the Hyundai Ionic D-Audio 2V dash.

In this series of write-ups [greenluigi1] put together for us, he walks us through the entire hacking process — and they’re a real treat to read. He covers a wide variety of things: breaking encryption of .zip files, reprogramming efused MAC addresses on USB-Ethernet dongles, locating keys for encrypted firmware files, carefully placing backdoors into a Linux system, fighting cryptic C++ compilation errors and flag combinations while cross-compiling the software for the head unit, making plugins for proprietary undocumented frameworks; and many other reverse-engineering aspects that we will encounter when domesticating consumer hardware.

This marks a hacker’s victory over yet another computer in our life that we aren’t meant to modify, and a meticulously documented victory at that — helping each one of us fight back against “unmodifiable” gadgets like these. After reading these tutorials, you’ll leave with a good few new techniques under your belt. We’ve covered head units hacks like these before, for instance, for Subaru and Nissan, and each time it was a journey to behold.

Quick Hack: The Phone To Stream Deck Conversion

July 18, 2022 by Al Williams 8 Comments

What do you do with those old Android or iPhone phones and tablets? You have plenty of options, but it is pretty easy to build your own stream deck with a little off-the-shelf software. What’s a stream deck, you ask? The name comes from its use as a controller for a live-streaming setup, but essentially, it’s an LCD touchscreen that can trigger things on your computer.

The software I’m using, Deckboard, is a server for Windows or Linux and, of course, an Android app. The app is free with some limitations, but for under $4 you can buy the full version. However, even the free version is pretty capable. You can use an Android phone or tablet and you can connect to the PC with a USB cable or WiFi. I’ve found that even with WiFi, it is handy to keep the phone charged, so realistically you are going to have a cable, but it doesn’t necessarily have to connect to the host computer.

Linux Setup

Setup is very easy. The biggest hurdle is you might need to set up your firewall to allow the server to listen on port 8500 with TCP. There are a few small issues when installing with Linux that you might want to watch out for. There are 32-bit and 64-bit versions in deb, tar.gz, and appimage format. There’s also a snap. The problem with the snap is it is sandboxed, so without effort you can’t easily launch programs, which is kinda the entire point. I finally removed it and installed the deb file which was fine.

There were still two other wrinkles. First, while Deckboard offers a way to launch programs, it must be a program from a list it reads from your system. That would be acceptable, but the list wasn’t complete. I never did figure out why some things show up on the list and others don’t. For example, GIMP which shows up on my application menu was absent. Yet other things that were fairly obscure did show up.

I thought this might be a dealbreaker until I found that Deckboard has a well-developed plugin system and one of those plugins lets you run an arbitrary command line. I guess it is a little less convenient, but it is much more flexible since you can launch any program you want and provide options to it as well.

The only other complaint I had is that when you run the program, it shows its configuration interface and puts itself in the system tray. That’s great the first time you run it, but on system startup, it would be nice to just have it quietly start. If there’s an option for that I haven’t found it. I’ll tell you how I solved that later, but, for now, just live with it.

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A Linux Business Card You Can Build

July 14, 2022 by Al Williams 22 Comments

It is a sign of the times that one of [Dmitry’s] design criteria for his new Linux on a business card is to use parts you can actually find during the current component shortage. The resulting board uses a ATSAMD21 chip and emulates a MIPS machine in order to boot Linux.

We like that in addition to the build details, [Dmitry] outlines a lot of the reasons for his decisions. There’s also a a fair amount of detail about how the whole system actually works. For example, by using a 0.8 mm PCB, the board can accept a USB-C cable with no additional connector. There is also a great explanation of the MIPS MMU and don’t forget that MIPS begat RISC-V, so many of the MIPS core details will apply to RISC-V as well (but not the MMU). You’ll also find some critiques of the ATSAMD21’s DMA system. It seems to save chip real estate, the DMA system stores configuration data in user memory which it has to load and unload every time you switch channels.

By the end of the post you get the feeling this may be [Dimitry]’s last ATSAMD21 project. But we have to admit, it seems to have come out great. This isn’t the first business card Linux build we’ve seen. This one sure reminded us of a MIDI controller card we once saw.

It’s Linux. On An ESP32

July 14, 2022 by Jenny List 30 Comments

By today’s standards, the necessities for running a Linux-based operating system are surprisingly meagre in terms of RAM and processor power. Back in the day we ran earlier Linux versions on Intel 386 and 486 machines with tiny quantities of memory compared to the multi-gigabyte many-core powerhouses we do today.

So it stands to reason that many of the more powerful microcontrollers should also run Linux, but of course they are often unable because the lack a memory management unit. The original ESP32 is just such a candidate, plenty of power but unable to run Linux. Not so fast, because [Dror Gluska] has managed to boot a Linux kernel on Espressif’s dual-core chip. How on earth? By emulating a RISC-V processor on it and booting a RISC-V version of the kernel.

The emulator in question is [Fabrice Belard]’s TinyEMU, a piece of software that brings both RISC-V and x86 to limited-spec platforms, and the write-up describes the extensive optimization and tracing of ESP32 bottlenecks which was finally able to get a Linux kernel booting in 1 minute and 35 seconds. Of course it’s simply an exercise to prove it can be done and we won’t be seeing Linux-based ESP projects any time soon, but it’s still an impressive piece of work.

This isn’t the lowest-spec microcontroller we’ve seen run Linux, back in 2012 we saw it on emulated ARM running on an 8-bit AVR.