[U-Boot] u-boot.img size limit ?

Hello list,

I'm using u-boot-2014.10 and trying to build it with LCD support for the Beaglebone black to include a Boot logo image. It seems that spl hangs while loading a 2.8MB sized u-boot.img ! I reduced the the logo header file and rebuild u-boot, that worked for a 1.6MB sized u-boot.img. Is there any size limit for u-boot ? how to increase the memory allocated by spl ?

Thanks you.