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uClinux: World’s most popular embedded Linux distro? (Part 2)

Sep 24, 1997 — by LinuxDevices Staff — from the LinuxDevices Archive — 1 views

Part 2: Recent events, and a promising future

By late 2001, Lineo was spinning off their acquisitions and the former Rt-Control team began to wonder how they might recover uClinux. Moreton Bay was renamed to SnapGear, and spun out of Lineo in late 2001. The Rt-Control group reorganized to form Arcturus Networks, and was spun out in early 2002; the rights to uClinux and associated trademarks returned to them.

Today, uClinux continues to improve, with 2.4.x kernel and uClibc upgrades, and ports for new processors including Conexant CX82100, and Samsung S3C45xx/S3C25xx parts with ARM cores. You can purchase uClinux-ready reference boards that offer a complete solution for firms using or considering such parts in their products; they also provide the basis for more complex network products or embedded controllers.

Another enhancement is bFLT support, first provided by SnapGear. The improvement of flat-model support used by MMU-less chips, is a boon to designers. Converters are available for elf2flt and coff2flt.

Yet another new addition is Arcturus' CrossFrame development environment for uClinux. Unlike GUI configurators, CrossFrame is an intuitive, extensible system for dealing with a variety of compilers and tool chain components. The system employs object-oriented definitions and inheritance to wrapper the most complex and arcane tool settings into a consistent set of commands that work with the designer; compare that to a few minutes of mouse-clicking followed by hours of typing. It can be used for nightly builds, automatic test and verification setups, and final-compile. The CrossFrame parser is available now, and more will be in alpha-test by the time you read this paper. A website is being setup to support the project, which is being released as an open source project.

In the near future, the connection between hardware and uClinux may get even tighter. The Arcturus team has been involved in system-on-chip (SOC) designs for years; even now, they are encapsulating critical pieces of networking support into hardware-renderable modules, delivered as VHDL code, for functions such as network packet processors. This is the same team that displayed uClinux-on-an-FPGA at ESC 2000; that seminal work led to the concept of hardware modules, with appropriate drivers, available and configurable through an understandable framework, running on the world's premier embedded OS. In other words, a real step forward in complete system integration.

Tuned solutions

As noted, several companies create products using specific hardware with uClinux and function-specific software. For example, uCdimm boards are available through The boards ship with full uClinux code, including kernel, libraries, and tools; there are several processor options. Another example is the SnapGear family of router/firewall products (pictured above). These are off-the-shelf replacements for boxes from Linksys, Netgear, and even Cisco.

Reference boards are available for Atmel, Conexant, Samsung, and other ARM processors too, many of them designed for the chip vendor with the specific goal of running uClinux. As with the uCdimm boards, the designs are proprietary, but can be licensed. The combination of solid hardware, flexible design, and access to the OS source plus tools, is unmatched.

uClinux-specific software is also available. For example, Arcturus uClinux software stacks include a full RG router with VPN and features such as VoIP, SmartCard, PC-Card, and HDLC support. All are tuned for uClinux, and available on several processors. Arcturus also has stacks for full-feature VPNs (including hardware encryption), a powerful MIB engine and libraries for remote configuration including SNMP and web interfaces, and a VoIP stack based on SIP, the emerging leader in network voice protocols. Even Jungo, though not a Linux company, ported a version of their RG stack to uClinux for the Conexant 82100 board.

Encapsulation of system components into market-ready stacks offers an incredible benefit to OEMs. RG stacks are a perfect example, since products in the RG market are under extreme cost and delivery pressure. uClinux-based solutions meet those requirements. Today, uClinux is the only embedded Linux that offers full-system deployable stacks from a single source (although Arcturus, Jungo, SnapGear, and perhaps other companies make them available for MMU-enabled Linux as well).

Summary and the future

uClinux continues to lead the deployed embedded Linux world. With dozens of ports, support for a variety of MMU-less and MMU-enabled processors, a solid code base, excellent libraries, and razor-sharp focus on the needs of system developers, the results are clear.

The originators of uClinux (and keepers of the project for the past 6+ years), are once again the holders of the project trademarks; this restores the focus and balance that was lost for a time, and points to a bright future for those who can benefit from this powerful, yet preeminently cost-effective, operating system. In addition to the venerable main uClinux project site, there are also new uClinux-related websites that focus on general embedded issues (, and for uClinux-ready products (such as and tools (such as CrossFrame).

Small, focused add-on libraries, such as uclibc and BusyBox, both currently maintained by CodePoet, add to the value without losing sight of the restrictions associated with deeply embedded products. Value-add services and stacks further extend the native Linux functions.

If you are involved in the design of true embedded system products or projects, and not just a rehash of a desktop box, uClinux warrants your attention. The embedded community need not worry about the viability of the world's first and foremost embedded Linux distribution — it remains in capable hands.

uClinux resources . . .

uClinux-oriented websites . . .

Companies supporting uClinux-based development . . .

About the author: John Drabik recently joined Arcturus Networks as Vice President of Technology. He has been involved in system design and development, for dedicated and embedded systems, for over 25 years. John has authored numerous articles and papers on embedded Linux, system design, business strategies, license issues, and product directions. He is the former VP and CTO for Digital Media at Lineo, the Chief Engineer and Architect of their DTV and RG stacks, and has done consulting work for several companies. John is also the former Technical Chair of the TV Linux Alliance.

uClinux-based device photo gallery

Click a picture to learn more about the device . . .

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