Bootloader build using waf


I built bootloader using ./waf bootloader for fmuv3 board. For FMUV3 FLASH_BOOTLOADER_LOAD_KB is defined as 16KB. I got an error at the end of the build console there was an error saying overloadedExceeded by 40KB’. When I changed the FLASH_BOOTLOADER_LOAD_KB to 20KB the error disappeared but ./waf copter command throws error saying ‘bad blimage size’. Can someone help me with the wayforward. Thanks