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Re: [LUG] Booting USB?

 

On Mon, 3 Mar 2008 12:32:36 +0000
Steph Foster wrote:

> On Sun, Mar 2, 2008 at 6:11 PM, Grant Sewell
> wrote:
> 
> > Hi all,
> >
> > Does anyone know a way to get GRUB to pass control over to a USB
> > device to boot?
> >
> > My laptop can boot from internal HDD, CD/DVD or network, but not
> > USB. I have permanently removed the DVD drive as it was knackered.
> > I have Ubuntu installed on it's internal HDD, but I also have an
> > external USB drive.  I would like to be able to boot the external
> > drive on the laptop, but alas the BIOS doesn't support USB-booting
> > of any nature.
> >
> > GRUB is a pretty capable system, so I was wondering if any of you
> > have done this?
> >
> > Cheers.
> > Grant.
>
> If you know the root device number for the usb drive you should be
> able to hack the grub config file and just change the root device
> number

That's just it... I have found that the device number seems to change
depending on what the BIOS does.

On my desktop machine, when opting to boot from one of the internal
harddrives, the external USB device is shown to be (hd2).  When opting
to boot from the USB device, the USB device is shown to be (hd0).  On
other machines I use this USB drive on, when choosing to "boot from
USB" via the BIOS, the USB drive appears as (hd0).  So far all of these
systems have had the option to boot from USB, so one could expect the
USB device to have already been probed to some extent.

However, on the laptop no such probing will have happened because it
doesn't support USB booting.

I will, when I get a chance, try setting GRUB to boot from (hd1) on the
laptop and see if it plays nicely.  Alternatively I guess I'm gonna
have to go down the route of keeping a copy of the USB drive's kernel
image and/or initrd on the laptop harddrive's /boot section.

Anyway, it's late and I'm knackered.  I'll report back when I've tried
it out.

Cheers.
Grant.

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