ChibiOS development on Debian using the Summon Arm toolchain: http://recursive-labs.com/blog/2012/05/ ... ios-linux/
. Haven't tried it on the Pi yet.
Plenty of folks using the Summon Arm toolchain for ChibiOS here: http://forum.chibios.org/phpbb/index.php
I believe that the Pi is great for size, cost, networking, processing, storage and UI but that the real time stuff ought to be delegated to something like the STM32F4DISCOVERY.