In embedded systems, a board support package (BSP) is an implementation of specific support code (software) for a given (device motherboard) 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 building programs to run on the embedded system (which would be part of the architecture support package), and utilities to configure the device (while running).