[syslinux] Fwd: Loading syslinux native from a USB HDD

[Nazo]

---------- Forwarded message ----------
From: Nazo <nazosan at gmail.com>
Date: Oct 18, 2006 8:02 PM
Subject: Re: [syslinux] Loading syslinux native from a USB HDD
To: "P.J. Dickson" <pauljohn at cogeco.ca>


On 10/18/06, P.J. Dickson <pauljohn at cogeco.ca> wrote:
> Hi there guys!
>
> I want to set up Puppy-Linux to run off a 2GB USB key-drive in native
> mode (I.e. not as a virtual machine, which I'm finding runs too slow on
> my system, under XP.)
>
> To test it out, I want to run off a 150GB USB HDD.  Now this drive is
> NTFS formatted and way bigger than the 1GB file structure limit that I
> read about in the Syslinux documentation.  There's only one partition on
> the USB HDD at the moment.  I've copied in the Puppy-Linux files
> (including syslinux.com) and I told the BIOS to boot from the USB.  It
> seems to go there but nothing happens, it just hangs.
>
> What have I got to do to make this beast run?
>
> Many thanks to anyone who can take the time to give me a few lines of
> advice.
>
> Paul
>
>
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>

Correct me if I'm wrong, but, last I heard Syslinux still has no
support for NTFS.  I don't know, I suppose since it would only have to
read that's not an entirely crazy idea, but, if it only supports
FATxx, it's still not going to run on NTFS, however similar reading
NTFS may be.

Anyway, one little thing you may want to do here is format that flash
drive with the special formatting tool included with Syslinux,
mkdiskimage.  This tool will make the flash drive sort of emulate the
structure of a zip disk.  The benefit here is that a flash drive
formatted this way is compatible with a lot more BIOSes that don't
support booting in USB-HDD mode.  You don't have to do this -- it will
still work as USB-HDD if you don't do it -- but it is a convenience
since you'll find very few BIOSes it won't work on like this.

Anyway, the only size limitations I know of would be that syslinux
probably can only handle up to a maximum kernel/initrd size (I think
this is what you read of being limited by 1 gigabyte?) and the BIOS
will not be able to boot any partition that starts past the 1024
cylinder boundary (beyond syslinux's control unfortunately.)  I'm
using an 80GB FAT32 formatted harddrive in an external enclosure and
have no troubles with syslinux on that drive with my current BIOS.
The only trouble I had is that the enclosure would not accept the ZIP
drive trick, so it only works on systems that support booting in
USB-HDD mode.

You may as well just go ahead with the flash drive too.  There's
really no reason to mess around with your USB harddrive when you can
always just wipe the flash drive clean and start over.  It's a lot
easier to back up 1GB worth of data compared to 150GB.  Oh, and here's
another little trick I like to use if you aren't already familiar with
it.  You can simply make a backup image of the flashdrive exactly as
it is before you start to mess with things (similar to the way a .ISO
file is an image of a CD-ROM disc's data.)  Just use dd with
if=/dev/sda (or whatever the correct letter was assigned to your
flashdrive as.)  As far as I know this gets MBR, partition table,
everything.  Thus if things go horribly wrong with, say the
mkdiskimage tool, I believe you should be able to restore your drive
to its original condition unless you just mess it up so badly that the
system won't even recognize it.

In the end, running linux off of a flashdrive is pretty simple stuff.
Syslinux can easily handle getting the kernel and initrd off of there.
 I keep a 512MB Cruzer Micro in my pocket which has my favorite linux
rescue disc distro, a stripped down minimal distro that only can run
Prime95, and a few other tools, and I have never had any troubles with
it and syslinux either.  There is one problem you have to deal with
though with most live distros.  Many live distros won't necessarily be
configured to be able to run from a flash drive.  They must be able to
load up the USB module during the early startup (often requires a
command line setting to tell them to do so) and other such things,
then they have to be able to look even at USB devices to find their
filesystem image.

- Ah, sorry, I had to forward.  I forgot to use reply all again.  )-: