older CHS interface. This works around stupid BIOSs who report that
int13 extensions are present and functional, but fail when you actually
use them. Like Adaptec SCSI BIOSs.
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.
little hacking by me. This isn't strictly identical to his 920312
release -- I've hacked it a bit -- but since we are taking over change
control it doesn't matter much.