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…
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…
U-Boot has long supported embedding a graphical image directly into the binary – like the boot logo and the recently added BGRT (Boot Graphics Resource Table) image for EFI systems. But the way these images were handled was a bit of a mixed bag, with different patterns for different images and custom boilerplate for each…
We’ve just rolled out a series of updates aimed at improving the U-Boot EFI application, with a special focus on streamlining the testing and debugging process, particularly for ARM platforms. This batch of 24 patches introduces several quality-of-life improvements, from better debugging tools to more robust boot procedures. Let’s dive into the key changes. Streamlining…
A robust and efficient test suite is the backbone of a healthy open-source project. It gives developers the confidence to add new features and refactor code without causing regressions. Recently, we’ve merged a significant 19-patch series that begins a much-needed cleanup of our Python test infrastructure, paving the way for faster, more reliable, and more…
The U-Boot boot process relies heavily on the Flattened Image Tree (FIT) format to package kernels, ramdisks, device trees, and other components. At the heart of this lies the fit_image_load() function, which is responsible for parsing the FIT, selecting the right images, and loading them into memory. Over the years, as more features like the…
What happens in the final moments before U-Boot hands control over to the operating system? Until recently, the answer was, “it’s complicated.” Each architecture like ARM, x86, and RISC-V had its own way of handling the final pre-boot cleanup, leading to a maze of slightly different functions and duplicated code. It was difficult to know…
