calling into firmware code is a big can of worms because firmware is full of bugs and only works with a small set of the major operating systems that the firmware authors tested it with.
and theres not really an option for doing it from userspace. you need to call it from kernel mode ring zero and make sure the firmware has the same idea of the virtual memory mappings as your kernel plus work arround the unstated assumptions of the firmware. linux has a track record of bricked machines and firmware corrupting memory. it is just not worth it. in 9front, the kernel never calls firmware. it does interpret a limited set of acpi methods on boot to figure out pci interrupt mappings and and then frees the acpi environment never to return. all efi/bios calls are done by the bootloader *before* it enters the kernel so we never have to rely on efi/bios firmware assumptoins. the bootloader collects the information from efi and passes it to the kernel as plan9.ini variables. efi firmware has a boot manager were the user can add and modify entries. -- cinap
