On Wed, 10 Mar 2010, Tejun Heo wrote:
How do you calculate geometry from newer Windows partition tables (cases
W-1, W-2 and W-3)?
By solving the equations matching CHSs and LBAs. It only works if the
first partition ends before the CHS address limit (2 variables to
solve for so we need 2 different equations).
Thanks for explanation. So with 64/32 geometry this should work for
partitions smaller than 1 GiB. With 255/63 geometry this limit is 8 GiB
and there are partitions bigger than that. Maybe for bigger partitions
BIOSes use ending CHS?
The only reason we're talking about geometry is for compatibility w/
older operating systems. So, at this point, diddling with geometry just
doesn't make any sense at all.
If we "do as Windows do" and make partitions aligned at 1 MiB but not
aligned at cylinder boundary, then there is no way to boot Windows 2000 or
older OS. If we use 64/32 geometry, there is a chance (maybe small) that
BIOS will calculate or assume correct CHS values and older OS can boot.
And this geometry cannot hurt newer OSes.
--
Tomasz Palac, AGH University of Science and Technology
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