[syslinux] BIOS disk geometry and Linux 2.6

[Michael Brown]

I have run into exactly this problem on several occasions, and it
certainly does suck.

The way I fixed it was to write a small "force_255_heads" patch. It
works for all IDE. I've also submitted a patch to libata so that all
SATA drives have this geometry. This sounds slightly more useful.  

--
Michael


On Thu, 2004-02-26 at 18:49, Patrick J. LoPresti wrote:
> I am working on a Linux-based boot disk for my project
> (http://unattended.sourceforge.net/), and I have hit a snag.
> 
> Under Linux 2.6, the kernel (via HDIO_GETGEO) always reports the C/H/S
> geometry of an IDE drive as X/16/63.  But most BIOSes want to use the
> geometry Y/255/63.
> 
> Most partitioning tools (including Parted) will take clues from an
> existing partition table and adapt to the BIOS values.  But if there
> is no existing partition table, they cannot do that.
> 
> This matters because I am installing Windows while running Linux, not
> unlike this other person:
> 
>   http://www.ussg.iu.edu/hypermail/linux/kernel/0312.2/0230.html
> 
> I can confirm that if I create a partition under Linux, format it, and
> run the Windows installer under dosemu, Windows is not able to boot.
> If I create the partition table under real DOS first, everything works
> fine.
> 
> Now for the on-topic part of this message.  What I want to do is
> invoke INT13/AH=08H in real mode to obtain the BIOS's idea of the
> geometry of disk 0x80, then boot Linux and pass that information in as
> a kernel command-line parameter.
> 
> My question is, can I do this with COMBOOT?
> 
> If not, does anybody have any other ideas?  This is a real
> show-stopper for me...
> 
> Thanks!
> 
>  - Pat
> 
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