Stay updated with the latest U-Boot development news, features, tutorials, and community highlights.
We’re excited to announce a significant new feature in U-Boot: a virtio-scsi driver. While U-Boot has long supported virtio-blk for block device access in virtualized environments, virtio-scsi offers greater flexibility, allowing a single virtio device to host multiple disks (LUNs) and supporting features like hotplug. This comprehensive 27-patch series, does more than just add a […]
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 […]
The integration of pytest with real boards (test.py) was written by Stephen Warren of Nvidia, some 9 years ago. It has certainly stood the test of time. The original code has been tweaked for various purposes over the years, but considering the number of tests added in that time, the changes are very small. Here […]
U-Boot has a new continuous integration (CI) lab page that provides a real-time look at the status of various development boards. The page, located at https://lab.u-boot.org/, offers a simple and clean interface that allows developers and curious people to quickly check on the health and activity of each board in the lab. When you first […]
Since 2018 U-Boot has had a good selection of features for running on top of QEMU, including: Most of this was written by Bin Meng. It uses driver model and is nicely implemented. What’s new? More recently a few more features have been added: The `virtio list` command can be useful for seeing what paravirtualised […]
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 […]
U-Boot Concept now supports the EFI Boot Graphics Resource Table (BGRT) feature. This enhancement allows for a more seamless and branded boot experience on devices that use EFI_LOADER, i.e. the Unified Extensible Firmware Interface (UEFI). What is BGRT? The BGRT is a table in the ACPI (Advanced Configuration and Power Interface) that allows the firmware […]
What is virtio-fs? For those unfamiliar, virtio-fs is a modern shared filesystem designed specifically for virtualised environments. It allows a virtual machine (the “guest”) to access a directory on the host system, but it does so with a focus on performance and providing local filesystem semantics. Unlike traditional methods like network filesystems (e.g., NFS, Samba) […]
U-Boot makes extensive use of linker-generated lists to discover everything from drivers to commands at runtime. This clever mechanism allows developers to add new features with a single macro, and the linker automatically assembles them into a contiguous array. The C code can then iterate through this array by finding its start and end markers, […]
In the world of software development, consistency is key. A recent update to U-Boot Concept takes a solid step in that direction by restructuring how it handles emulation targets. This change makes life easier for developers working across different processor architectures. Previously there were inconsistencies in the configuration system (Kconfig). For example, enabling QEMU emulation […]
U-Boot has a new continuous integration (CI) lab page that provides a real-time look at the status of various development boards. The page, located at https://lab.u-boot.org/, offers a simple and clean interface that allows developers and curious people to quickly check on the health and activity of each board in the lab. When you first visit the page, you’ll see a grid of all the available boards. Each board’s card displays its name and current status, making it easy to see which boards are online and which are not. A single click on any board will show a console view, taken from the last health check. This allows you see why boards are failing, for example. This new lab page is a nice resource for the U-Boot community. It provides a transparent and accessible way to monitor this part of the CI system. Check it out and get in touch […]
The integration of pytest with real boards (test.py) was written by Stephen Warren of Nvidia, some 9 years ago. It has certainly stood the test of time. The original code has been tweaked for various purposes over the years, but considering the number of tests added in that time, the changes are very small. Here is a diffstat for the changes up until a recent rename: When Stephen wrote the code, there was no Gitlab system in U-Boot (it used Travis). Tom Rini added Gitlab in 2019: test.py mostly just worked in that environment. One of the reasons the code has proven so stable is that it deals with boards at the console level, simply relying on shell-script hooks to talk start up and communicate with boards. These scripts can be made to do a lot of different things, such as powering boards on and off, sending U-Boot over USB, […]
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 “loadables” property were added, this important function grew in size and complexity. While it was a significant improvement over the scattered code it replaced, it had become a bit unwieldy—over 250 lines long! Maintaining and extending such a large function can be challenging. Recognizing this, U-Boot developer Simon Glass recently undertook a refactoring effort to improve its structure and maintainability. A Classic Refactor: Divide and Conquer The core strategy of this patch series was to break down the monolithic fit_image_load() function into a collection of smaller, more focused helper functions. This makes the code easier […]
We’re excited to announce a significant new feature in U-Boot: a virtio-scsi driver. While U-Boot has long supported virtio-blk for block device access in virtualized environments, virtio-scsi offers greater flexibility, allowing a single virtio device to host multiple disks (LUNs) and supporting features like hotplug. This comprehensive 27-patch series, does more than just add a new driver. To make virtio-scsi a reality, U-Boot’s entire SCSI subsystem has received a much-needed modernization, resulting in a faster, more robust, and more maintainable implementation for all SCSI devices. Smarter Scanning with REPORT LUNS One of the most significant improvements is in how U-Boot discovers SCSI devices. Previously, a scsi scan would blindly iterate through every possible target and Logical Unit Number (LUN). In a QEMU environment, this could mean checking up to 256 targets, each with 16,384 LUNs—a time-consuming process for finding just one or two disks. The SCSI subsystem now uses the […]
