Hi,
I currently have a Micronics C400 motherboard
(www.diamondmm.com) using an older version of the Award BIOS.
I recently purchased a 40 GB hard-drive and need to be able to boot
off of it as well as use the full 40 GB in Linux.
Unlike other drives, where cylinder limits only changes the cylinders
reported, on this drive it also changes the LBA capacity to 66055248.
I can only assume that the real LBA capacity is then stored
elsewhere. With EZ-Drive loaded, at least EZ-Drive will set the
CHS to the correct size (for any drive over 8GB, heads is 255 and
sectors is 63 for EZ-Drive, cylinders is dependent on the capacity of
the drive, but is always over 4111 on a drive over 32GB).
So, there are two possible solutions. Either figure out where the new
LBA capacity is written on these drives, and use it when what we
thought was LBA capacity == 66055248. Or we can do some testing in
the lba_capacity_is_ok function. For a quick fix, having
lba_capacity_is_ok return 0 if the LBA capacity is 66055248 and the
heads are 255 and the sectors are 63 and the cylinders are greater
than 4111 will cause init_idedisk_capacity to use C*H*S as the
capacity, which in this case is more correct.
Note that the C*H*S is not exactly the full capacity of the drive as
reported. My drive has 4982*255*63 reported by EZ-Drive (and also
this is what Linux will deduce from the LBA capacity when clyinder
limits jumper is not set). However, 4982*255*63 is only 80035830
while my drive's LBA capacity (as reported without cly. limits set) is
80041248. So I lose a few sectors (not that big of a deal as long as
I take care to not put a partition past that point, which I don't even
think fdisk will let you do).
As far as finding the new LBA capacity field, I guess it would be in
one of the reserved fields, but I haven't checked yet. As far as
faking the capacity using info from EZ-Drive, that's kind of a hack,
but it'd work if we couldn't find the real LBA somewhere
-Dave
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This archive was generated by hypermail 2b29 : Thu Mar 23 2000 - 21:00:39 EST