[syslinux] BIOS disk geometry and Linux 2.6

[Patrick J. LoPresti]

"H. Peter Anvin" <hpa at zytor.com> writes:

> How about this: a COMBOOT/COM32 program queries for BIOS geometry and
> writes them into Sector 1 of the hard disk together with a signature
> Then you can read them from there.  Again, since you're actually
> writing the data to the disk, the BIOS:Linux drive mapping problem
> becomes trivial.

This still does not let you do the mapping in general.  Any drive
might have been moved from any machine.

Or do you clobber sector 1 on every attached drive?  Seems risky...
And don't some boot loaders use sector 1?

Just out of curiosity, why is it such a bad idea to pass the geometry
as a kernel parameter?

I suppose it might be better just to add a field to the EDD data and
fill it in from setup.S...  Hm.

I still think the geometry issue and the device mapping issue are
completely independent and need to be solved separately.

The geometry issue is critical for me, and it can be solved without
any scribbling on the disk just by asking the BIOS a few questions.

The device mapping issue is harder, but on the other hand it is about
1000 times less important.  Almost all of my users only have one
drive; for the rest, I am happy to tell them "use a newer BIOS or
choose the boot device manually".  And even without EDD 3, I can take
a pretty good guess at the boot device.

 - Pat