[syslinux] Booting a USB drive

[Gene Cumm]

On Sat, Feb 26, 2011 at 15:51, Rance Hall <ranceh at gmail.com> wrote:
> I have a 40GB IDE laptop hard drive I took out of a dead laptop and I
> was hoping to put some good use to it.
>
> The drive is inside a USB drive enclosure and I carry it in my laptop bag.

> syslinux seemed like a decent alternative and I figured I could use
> most of the same syslinux configuration for my in house pxelinux
> configuration.

I do the same but I use SYSLINUX, ISOLINUX and PXELINUX.  I've been
able to construct everything to be portable to all of these variants.

> But I have been reading alot on how to do this and I keep finding
> reasons to be wary.
>
> Am I wasting my time?  Should I just use a basic key without the
> prolific chip?  What is the best way to proceed?

Personally, I've had zero experience with these chipsets however there
are some generic tests that you can do to test the viability of this
system.

* With USB Boot enabled, boot from a CD or PXE.  Sometimes (but not
always) the BIOS will present the USB HDD as a drive.  HDT
(com32/hdt/hdt.c32) provides a great way to see available hard drives
and their reported geometry.  Most of the time, a drive that size will
have a H/S geometry of 255/63.  I've had better luck with seeing the
USB drive from non-USB boot when multiple USB drives are present.

* Copy in an MBR ('d recommend mbr/mbr.bin from Syslinux), create a
small FAT partition aligned on cylinders of H/S 255/63, install
SYSLINUX and copy in HDT.  Run HDT and see what it says for geometry.

Your best bet for creating something usable (with regards to
compatibility with broken BIOSs) is to probably have a boot partition
at CHS 0,1,1 (the first normally usable sector) and use a H/S drive
geometry of 255/63 or copy the ZIP100/ZIP250 geometry (H/S 32/64) and
keep the end of the partition below cylinder 1023.  Some BIOSs are
(unfortunately) only capable of USB-ZIP mode booting.

-- 
-Gene