In the world of embedded systems, a Flattened Image Tree (FIT) is the standard way to package a bootable OS, typically bundling the kernel, a ramdisk, and the necessary devicetree (FDT) into a single, verifiable file. While convenient, this approach tightly couples the OS with its hardware description. But what if the OS and the…
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,…
