Add a missing =m constraint to the EDD-probing code, that could have
caused improper dead-code elimination.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Some BIOSes require that sector buffers not cross 64K
boundaries.  As a result, we compute a dynamic address on the
setup heap.  Unfortunately, this address computation was just
totally wrong.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Probe EDD and MBR signatures, in order to make it easier to map
physical hard drives to BIOS drives.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>