the bit is set that declares the geometry valid. The spec itself says
that this field isn't covered by the "geometry valid" bit, but at
least one BIOS implements it that way.
and sysctl to export to userland). Also, only use total number of sectors
given in the extended parameters if the physical chs geometry is
marked invalid. Hopefully fixes a problem where BIOSs would not correctly
fill in this field.
drochner