🚀 go-pugleaf

"Rod Speed" <rod_speed@yahoo.com> wrote:

>> This is a really nasty bug.
>
>You appear to be confusing the undoubted problem with changes
>to the mapping between the CHS values and the LBA block numbers
>that can certainly vary with the OS level mapping, and what the bios
>does at boot time with an AUTO drive type, what was being discussed.

The OS has nothing to do with this. Let me give you an example.

Award BIOS with extended interrupt 13h (disk) support. A 9671 MB IDE
harddisk. The disk is set to User/LBA, and the disk has a BIOS
translation of 1232 cylinders, 255 heads, 63 sectors. With this
translation 9664 MB are useable.

A 9664 MB partition is created. The partition table is correct, and
assumes a 255 heads translation.

The disk has 19,807,200 sectors. We look at LBA sector 10,000,000
(numbered from 0). This will be

cylinder 622, head 120, sector 11

Then we reboot, and enter BIOS setup. LBA mode is changed to NORMAL
mode. A translation of 19650 cylinders, 16 heads, 63 sectors is
displayed. We save the change and boot.

Then we request the disk geometry by calling BIOS interrupt 13h. The
answer is 1232 cylinders, 255 heads, 63 sectors.

Then we call BIOS interrupt 13h, function 42h, and request LBA sector
10,000,000. A sector is returned.

Everything looks OK, but it is definitely not sector 10,000,000 that
is returned.

Then we use interrupt 13h, function 02h, to request cylinder 622, head
120, sector 11.

Again: Everything looks OK, but it is definitely not sector 10,000,000
that is returned.

Please note that this is only one of the Award bugs. The one that I
called nasty.
-- 
Svend Olaf