[syslinux] After USB boot problems on Gigabyte GA-M55Plus-S3G

[H. Peter Anvin]

On 01/21/2014 09:07 AM, Thomas Schmitt wrote:
> Hi,
> 
> hpa wrote:
>> LBA = (C * H' * S') + (H * S') + (S - 1)
>> [...]
>> Start LBA       63 = CHS    0   1   1
>> End   LBA 15794175 = CHS  982 254  63
>> If LBA 63 = CHS 0/1/1 then we know S'=62, but that is completely
>> inconsistent with the ending sector being 63.
> 
> Wouldn't that be S'=63 ?
> 63 = (0 * H' * 63) + (1 * 63) + (1 - 1)
> 

Oh, right.  Mental fault on my part.

> Whatever, the stick producers seem to take the same freedom
> as needed when the disk size exceeds 1023*255*63 :
> Start LBA plus blocksize does not need to match end CHS.

Well, at that point it really *can't*.  The best practice seems to be to
make the end CHS equal to 1023/H'/S' at that point.

> Ady's understanding seems not uncommon, that the end CHS address
> shall indicate H' and S' by (H + 1) and S.

Right.

> I wonder if this is specified anywhere.
> (It is equivalent to cylinder alignment of the partition end.)
> 
>  
>> Fortunately geometry is becoming a fading problem.  We're dealing with
>> an old board and BIOS here.
> 
> My own hardware is of similar age.
> 
> I am getting more and more pessimistic with the idea to
> propose at least one "normal" MS-DOS filesystem setup.
> If not Ady comes to the rescue, that is.

There is one... the closest thing we have found to work mostly
everywhere is a 64/32 CHS, with 255/63 as reasonably close second.  The
mkdiskimage tool in the Syslinux distribution exists for this reason.

	-hpa