[Updated Jun 24] — Linux.com interviewed Wolfgang Denk, founder of Denx and the creator of the U-Boot bootloader. The embedded Linux pioneer spoke on a range of issues including the future of U-Boot, the importance of Yocto Project code and how it has changed Denx’s own ELDK distribution, and the growth of ARM and real-time Linux in embedded computing.
The open source U-Boot bootloader is such a given in so many embedded Linux projects that we tend to forget that it’s still a growing project, changing with the times. That assessment could apply to its inventor, Wolfgang Denk, who founded the German embedded Linux engineering firms Denx Software Engineering and Denx Computer Systems 1999 and 2000, respectively, and introduced “Das U-Boot” a decade ago.
To see what was up with U-Boot, and gain a longer-range perspective on the embedded Linux scene, Linux.com’s Libby Clark recently interviewed Denk, who is now managing director of both Denx companies.
Denk gave up his role as U-Boot maintainer last year, but continues to be closely involved with the project. Interesting new features include improved support for cryptographically signed images, as well as a new fast-booting “Falcon” boot mode, which has been demonstrated to boot in 3.08 seconds, from power-on to when a graphical Qt application starts running. (Note: a given system’s boot time “depends a lot on the actual hardware — on one board we may need more than 5 seconds, while on another we may get below 1 second,” wrote Denk in an email to LinuxGizmos.) The project is now working on adapting the Linux kernel’s Kconfig approach for configuration, and developing a new device driver model, Denk told Linux.com.
According to Denk, the most significant trends in embedded Linux in recent years include the widespread adoption of the Linux Foundation’s Yocto Project code, and the surprisingly smooth transition from embedded platforms like PowerPC to ARM.
Like many embedded Linux distributions, including Wind River Linux, Enea Linux, and Mentor Embedded Linux, Denx’s Embedded Linux Development Kit (ELDK) has switched to a foundation using the Yocto Project embedded stack and OpenEmbedded-based build system. “The Yocto Project has become the best approximation of a standard Linux distribution for embedded systems we ever had so far,” Denk told Linux.com. “This is really a great achievement.”
Both the software and hardware wings of Denx have been part of the embedded industry’s migration from the PowerPC and MIPs architecture to a growing adoption of ARM. Recent ARM-based products include Denx’s M53 COM, based on Freescale’s i.MX535 or i.MX537 SoCs, and its M28 COM, based on Freescale’s i.MX287 SoC.
Denx i.MX287-based M28 and i.MX53x-based M53 COMs
(click images to enlarge)
According to Denk, the smooth transition is a testament to Linux’s maturity and flexibility. “If you consider the landslide-like move from Power Architecture to ARM systems in the last two or three years it is highly notable that this happened without disconcertment for both developers and users,” said Denk. “Thanks to Linux, the low level hardware details are well abstracted away.”
Some other major embedded trends noted by Denk in the Linux.com interview include:
- Increasing use of real-time Linux in general, and Xenomai in particular, as an alternative to real-time operating systems (RTOSes)
- Limited near-term role for Android in general embedded computing
- Growing compliance with pushing code upstream to mainline Linux and projects like U-Boot
- Widespread interest in ARM/FPGA SoC combos such as the Zynq Z-7020 and Altera Cyclone V
- The enduring contribution of Git