Re: chain loading USB harddrive if no native USB support possible?

[Franklin PIAT]

On Fri, 2008-04-04 at 05:51 +0200, Michael Reichenbach wrote:
> I have a comp here without native USB support. The bios can not boot 
> from USB directly. Booting from CD, HD and floppy works.
> 
> In grub shell with null ( I also does not see the device, only the 
> internal harddisk.
> 
> On google I did already found instructions to successfully chain load CD 
>   with grub.
> 
> Isn`t this possible also for USB? I mean, first boot grub from cd or 
> floppy, then load a linux kernel, he makes the USB device usable and 
> then chain load USB?

I guess that nothing prevents you from installing grub on a floppy or CD
with its config file. The tricky part will be to tell grub to search for
a given file, in order to identify the [USB] root device.

Under grub2, you can use the "search" command (read [1] for more
information).

I haven't tested, but if you label the USB device with a unique name,
then a script like this should work:
 search -f MyUsbLabel
 linux  /boot/vmlinuz root=LABEL=MyUsbLabel ro
 initrd /boot/initrd.img

(try googling for "search -f" for tested examples)

Franklin


[1] http://wiki.debian.org/Grub/grub.cfg.manpage