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PowerPC networking SoCs gain real-time Linux support

Jun 28, 2006 — by LinuxDevices Staff — from the LinuxDevices Archive — 1 views

A commercial real-time Linux variant offering separate real-time and non-real-time execution domains has added support for a family of network processors that integrate separate application and control plane processing units. FSMLabs's RTLinuxPro development kit now supports Freescale's PowerQUICC III family of SoCs (system-on-chip processors).

The PowerQUICC III SoCs target smart packet forwarding, routing, and security in core and edge devices and blades. They integrate two processing units, with the aim of enabling a single chip to handle both control- and data-plane processing. Control-plane processing is handled by a PowerPC e500 core clocked at 667 or 833MHz, while data-plane processing can be offloaded to a communications processor module (CPM). The CPM can be programmed in microcode to execute various operations. It appears as a hardware device to the OS, according to FSMLabs CEO Victor Yodaiken.

Block diagram of the MPC8560, one member of Freescale's PowerQUICC III family
(Click to enlarge)

FSMLabs's RTLinuxPro product includes a nanokernel that provides a real-time domain based on the POSIX 1003.13 API. In addition, this “RTCore” nanokernel runs as its idle task a Linux kernel modified to use RTCore's interrupt controller service rather than the hardware's interrupt controller.

FSMLabs says developers targeting 833MHz e500 cores can expect worst-case RTCore interrupt latencies of 1.7 microseconds, and worst-case real-time context-switches of 8.5 microseconds. These timings can be measured with the standard Linux guest operating system “fully loaded and servicing heavy network traffic,” according to the company.

Rich Schnur, segment manager for Freescale's Digital Systems Division, stated, “FSMLabs has pioneered real-time Linux OS solutions for PowerQUICC processors, and today RTLinux helps keep the PowerQUICC family of communications processors at the forefront of network designs.”

FSMLabs's director of engineering, Cort Dougan, was the “primary original author of Linux for PowerPC,” the company boasts.


RTLinux and associated development tools are available now for PowerQUICC III processors that include the MPC8540 and MPC8560, as well as for other processors based on the e500 core.

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