Debugging embedded bootloaders can often feel like working in the dark. When execution crashes or behaves unexpectedly, the first question an engineer usually asks is, “How did I get here?” Of course, one should always have a JTAG debugger ready to press into service, but so few boards provide a JTAG header. To help, a…
In the world of U-Boot, the Device Model (DM) and Device Tree (DT) are the standard for hardware description. However, U-Boot runs on a massive variety of hardware, including constrained systems where full Device Tree support (OF_REAL) might be disabled. A recent patch cleans up how the core handles these “no-Device-Tree” scenarios, ensuring that code…
U-Boot is a massive project. With thousands of files, nearly endless configuration possibilities, and complex Kconfig dependencies, a single board configuration often only compiles a small fraction of the total source tree. For developers and maintainers, this complexity often leads to difficult questions: Simply searching for CONFIG_ macros or header inclusions is rarely enough. The…
Flattened Image Trees (FIT) are a cornerstone of modern U-Boot booting, offering a flexible way to package kernels, device trees, ramdisks, and firmware. However, the code responsible for printing information about these images—the output you see when running mkimage -l or iminfo—has been around for a long time. As with any legacy code, it had…
Over the last few months (and since the last post) the mouse support in U-Boot Concept has matured quite a bit. The various performance improvements have had a big impact and the UI is now smooth and useable. Here’s a video: So what’s next? Let’s look at a few topics. Touchpads So far touchpads are…
We’re excited to announce that U-Boot concept has merged support for unlocking LUKSv2 encrypted partitions! This is a significant enhancement to U-Boot’s security capabilities, allowing it to handle the encryption standard used today by most current Linux distributions. This 16-patch series (and a small follow-up) bring U-Boot up to speed with modern disk encryption, building…
Expo is U-Boot’s forms and UI subsystem. It supports text, images and menus and a large expo can contain quite a bit of information. How do you debug and understand that? Tracing through large, linked data structures is not fun. U-Boot Concept now has an expo_dump() function, designed to be called from your code when…
My first ARM machine was an Archimedes way back in about 1987. I received the first unit sold in New Zealand. At some point my machine started running Acorn’s RISC OS. For me, some of the amazing things about RISC OS were anti-aliased outline fonts, a string-sound generator which worked without a data table and…
Expo is U-Boot’s menu- and GUI-layout system. It provides a set of objects like text, images and menu items. Expo allows these objects to be positioned on the display. Most importantly it can render the objects onto the display. Input delays The typical loop polls the expo for input (keyboard or mouse), does any required…
Testing boot scenarios in very important but there are quite a lot of them! Concept currently has about 13 images containing various partitions and files used by the bootstd tests. These are listed in test.dts, for example: All images are built by test_ut_dm_init_bootstd(), but most of these are disabled by default, to avoid making sandbox…
