Thanks for your interest in the Intel Joule Platform.
The available OS for the Joule are listed below:
-Reference Linux* OS for IoT (Ostro)
-Ubuntu* 16.04 Desktop and Core (beta)
-Windows® 10 IoT Core
For more information, please follow this link: https://software.intel.com/en-us/iot/hardware/joule The Intel® Joule™ Compute Module | Intel® Software . Also, you should know that in this community, we only support the Ostro OS.
If you are interested in running Porteus Linux in the Joule Board I would recommend contacting the Portheus community: http://forum.porteus.org/ Porteus - Index page .
Have a nice day!