Re: IDE disk geometry + patch
Fri, 4 Dec 1998 18:24:47 +0100 (MET)

From Fri Dec 4 14:43:19 1998

I saw this recently on new fujitsus.
Reported 1023,255,63 after selecting LBA.
Result complete muddle until I realized that _smart IDE disk_
(or somesuch) had been enabled in the bios. Turned it off and all OK.

But LBA has _always_ been the preferred access mode for linux.
Are you saying that it is not? Please explain!


No. This has nothing to do with disk access.
It only concerns the geometry returned by the
HDIO_GETGEO ioctl (as used by fdisk and LILO).

Note that all these numbers are fake and have
no relation to any hardware parameters.

The rules of the game are:
(i) C*H*S is total disk capacity
(ii) Only change H and S in emergency cases because
it may confuse other operating systems on the same disk:
H and S are used in conversions of LBA addresses to 3D addresses.

The conclusion is that one should always put
C := capacity/(H*S).


[If you still have these Fujitsus you can check whether
the change I suggested avoids your complete muddle in
all cases, regardless of BIOS settings.]

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