RE: Why check legacy partition table for non-legacy HDs?

[Matt_Domsch]

> "Cylinders" isn't a value you have access to.  In fact, we can't ask
> the BIOS anything.  All information we get is deduced.

I'm working on adding BIOS EDD 3.0 support to the kernel (do the calls in
real mode before the switch to protected mode).  At that point we can get
(for BIOS-known disks):

* Number of default cylinders. The content of this field shall be one
greater than the maximum
cylinder number. INT 13h Fn 08h shall be used to find the logical number of
cylinders.

* Number of default heads. The content of this field shall be one greater
than the maximum head
number. INT 13h Fn 08h shall be used to find the logical number of heads.

* Number of default sectors per track. The content of this field shall be
the same as the maximum
sector number because sector addresses are 1 based. INT 13h Fn 08h shall be
used to find the
logical number of sectors per track.

* more stuff that I really want (PCI location, SCSI location, ...)

The EDD 3.0 spec is on www.t13.org, isn't final, and isn't widely
implemented yet.  But...
(I need to find the spec that has int 13 fn 08 stuff - probably a recent ATA
spec).  At that point we have the info if we want it.

-Matt

--
Matt Domsch
Sr. Software Engineer, Lead Engineer, Architect
Dell Linux Solutions www.dell.com/linux
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