Comment 67 for bug 403408

Same bug hit me too, trying to install 9.10 after 10 Gb partition on 40 Gb disk. Fiddling w/ partitions
showed critical point at 8 Gb, resulting in rescue mode if last install was above that, or just an
unbootable menuitem (UUID mismatch) for an earlier install above 8 Gb.

8 Gb is one of many breakpoints at which BIOSes needed fixes to the cyl-head-sector mapping to
address disks exceeding that size. My MB is new enough to use the latest "permanent" fix, LBA mode,
so I didn't expect such a bug. However, configuring the BIOS to use AUTO mode (which chooses CHS
mapping) instead of LBA mode and reinstalling (grub-install at a minimum) fixes the problem.

This makes sense. If grub always used the latest, best BIOS call then it wouldn't work on old MBs.
If it used the oldest BIOS call that was supposed to be able to handle the particular disk size then
it would work with all MBs but require that BIOS be set to the same mode grub chooses. Hopefully
BIOS AUTO chooses a mode by the exact same algorithm.