initramfs size limitation

Is there any limitation for the initramfs image size? If yes, how can I change this limitation?

The problem starts when the initramfs image size is larger than about 15MB. The ‘insmod’ command for loadable modules is failed. Example of error: “insmod: can't insert '/lib/modules/2.6.32/gdmslte.ko': invalid module format”

 Thanks,

  Ariel