In embedded systems, a board support package (BSP) is implementation specific support code for a given board that conforms to a given operating system. It is commonly built with a bootloader that contains the minimal device support to load the operating system and device drivers for all the devices on the board.
Some suppliers also provide a root file system, a toolchain for making programs to run on the embedded system (which would be part of the architecture support package), and configurators for the devices (while running).