Constant sunrise_kernel::frame_allocator::i386::FRAME_BASE_LOG

const FRAME_BASE_LOG: usize = 12;

The right shift to perform to a Physical address to get its frame id.

let phys_address = PhysicalAddress(0xabcde567);

let frame_id = phys_address >> FRAME_BASE_LOG;
assert_eq!(frame_id, 0xabcde);