1. A method of computer processor execution of UEFI firmware supporting pre-boot initialization of a bootloader program from a plurality of bootloader programs, the UEFI firmware located in a memory, the memory operatively coupled to the processor, the method comprising: executing, by the processor, the UEFI firmware; when executing the UEFI firmware: detecting type of instruction set of the processor; determining a bootup selection mode according to a mode selection, wherein the bootup selection mode corresponds to the detected type of instruction set, and the mode selection corresponds to the type of a bootloader program for execution after the UEFI firmware; retrieving, by the processor, a common configuration data from a plurality of configuration data of the UEFI firmware from the memory; retrieving, by the processor, a distinct configuration data from the plurality of configuration data of the UEFI firmware corresponding to the bootup selection mode from the memory, wherein the distinct configuration data comprises processor instruction sets and runtime services; generating a bootloader address corresponding to the bootup selection mode; and executing, according to the common configuration data and the distinct configuration data, the bootloader program located in a storage corresponding to the bootloader address.