SnapGear released a version of the GPL, royalty-free uClinux and tool chain for the Intel Xscale-based IXP425. The operating system works with RTLinux (www.fmslabs.com) and RTAI (www.aero.polimi.it/~rtai/) if real-time support is required. A memory management unit (MMU) isn't necessary for uClinux. It works with a range of other processor architectures, including ARM and Motorola's ColdFire/Dragonball families.
www.snapgear.com