[syslinux] SYSLINUX GRUB and booting logical partitions on USB drive

[H. Peter Anvin]

greenfinch wrote:
> 
> Where is the limitation?
> Is is SYSLINUX or GRUB?
> Maybe someone can help me to be able to chainload SYSLINUX from an 
> logical partition.
> 

Last I checked, Grub passed an invalid partition offset in DS:SI when 
chainloading a logical partition.  Syslinux is partition-table-format 
agnostic, and uses the information passed into it.  However, the format 
of DOS partition tables are such that anything that tries to boot a 
logical partition (keep in mind that MS-DOS couldn't boot logical 
partitions at all) has to adjust the partition offset; the stuff that 
comes off the disk is relative to the extended partition that surrounds 
the logical partition, but the chainloaded operating system has no way 
of knowing that.

	-=hpa