Detect which OMAP processor
From Gumstix User Wiki
To determine which OMAP processor is in the Overo computer-on-module (eg OMAP3503 processor or OMAP3530), look for the following information in the boot-up message:
"OMAP3503-GP rev 2, CPU-OPP2 L3-165MHz" implies OMAP3503 (Overo Earth and Overo Air)
whereas the message:
"OMAP3530-GP rev 2, CPU-OPP2 L3-165MHz" implies OMAP3530 (Overo Water and Overo Fire).
All u-boots after Tuesday, February 3 2009 have the proper CPU detection.
u-boot dated prior to February 3rd, 2009 does not have proper CPU detection so a u-boot update may be needed to obtain this information.