Stay updated with the latest U-Boot development news, features, tutorials, and community highlights.
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 supports a fairly wide variety of filesystems, including ext4, ubifs, fat, exfat, zfs, btrfs. These are an important part of bootloader functionality, since reading files from bare partitions or disk offsets is neither scalable nor convenient. The filesystem API is functional but could use an overhaul. The main interface is in fs/fs.c, which looks […]
VBE has been a long-running project to create a smaller and faster alternative to EFI. It was originally introduced as a concept in 2022, along with a sandbox implementation and a simple firmware updater for fwupd. In the intervening period an enormous about of effort has gone into getting this landed in U-Boot for a […]
A few weeks ago I took a look at Qboot, a minimal x86 firmware for QEMU which can boot in milliseconds. Qboot was written by Paolo Bonzini and dates from 2015 and there is an LWN article with the original announcement. I tried it on my machine and it booted in QEMU (with kvm) in […]
Welcome to the new official blog for Das U-Boot! For over two decades, the U-Boot mailing list has been the vibrant hub of our development discussions. While the mailing list remains our primary channel for patches and technical conversations, this blog will serve as a new platform to share deeper insights, project news, and community […]
Welcome to the new official blog for Das U-Boot! For over two decades, the U-Boot mailing list has been the vibrant hub of our development discussions. While the mailing list remains our primary channel for patches and technical conversations, this blog will serve as a new platform to share deeper insights, project news, and community stories in a more accessible format. As of mid-2025, U-Boot is more critical to the embedded ecosystem than ever. Our development is thriving, with robust support spanning a vast array of architectures from ARM and x86 to the rapidly expanding world of RISC-V. U-Boot provides a flexible, powerful foundation for countless products in the industrial, automotive and consumer-electronics spaces, incorporating modern standards like FIT, EFI and Firmware Handoff to meet today’s demanding security and interoperability requirements. This blog is a community platform, and we need your voice to make it a success. We invite developers, […]
A few weeks ago I took a look at Qboot, a minimal x86 firmware for QEMU which can boot in milliseconds. Qboot was written by Paolo Bonzini and dates from 2015 and there is an LWN article with the original announcement. I tried it on my machine and it booted in QEMU (with kvm) in about 20ms, from entering Qboot to entering Linux. Very impressive! I was intrigued as to what makes it so fast. There is another repo, qemu-boot-time by Stefan Garzarella, which provides an easy means to benchmark the boot. It uses perf events in Linux to detect the start and end of Qboot. Using x86 post codes, I added the same to U-Boot. Initially the boot time was 2.9 seconds! Terrible. Here is a script which works on my machine and measures the time taken for U-Boot boot, using the qemu-x86_64 target: It turned out that almost […]
VBE has been a long-running project to create a smaller and faster alternative to EFI. It was originally introduced as a concept in 2022, along with a sandbox implementation and a simple firmware updater for fwupd. In the intervening period an enormous about of effort has gone into getting this landed in U-Boot for a real board. This has resulted in 10 additional series, on top of the sandbox work: A – Various MMC and SPL tweaks (14 patches, series) B – binman: Enhance FIT support for firmware (20 patches, series) C – binman: More patches to support VBE (15 patches, series) D – A collection of minor tweaks in MMC and elsewhere (18 patches, series) E – SPL improvements and other tweaks (19 patches, series) F – VBE implementation itself, with SPL ‘relocating jump’ (22 patches, series) G – VBE ‘ABrec’ implementation in TPL/SPL/VPL (19 patches, series) H – […]
U-Boot supports a fairly wide variety of filesystems, including ext4, ubifs, fat, exfat, zfs, btrfs. These are an important part of bootloader functionality, since reading files from bare partitions or disk offsets is neither scalable nor convenient. The filesystem API is functional but could use an overhaul. The main interface is in fs/fs.c, which looks like this: At first glance this seems like a reasonable API. But where is the filesystem specified? The API seems to assume that this is already present somehow. In fact there is a pair of separate functions responsible for selecting which filesystem the API acts on: When you want to access a file, call either of these functions. It sets three ‘global’ variables, fs_dev_desc, fs_dev_part and fs_type . After each operation, a call to fs_close() resets things. This means you must select the block device before each operation. For example, see this code in bootmeth-uclass.c: […]
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 for ARM systems used the ARCH_QEMU symbol, while x86 systems used VENDOR_EMULATION for a similar purpose. This could create confusion and added complexity when managing board configurations. To resolve this, a new, architecture-neutral symbol, MACH_QEMU, has been introduced. This single, unified option replaces the separate symbols for both ARM and x86 emulation targets. This small but important merge tidies up the codebase, creating a more consistent and intuitive developer experience. It also sets the stage for future work, with the potential to extend this unified approach to other architectures. It’s a great example of the […]
