Problem with booting from Compact Flash card

[Joerg Schoppet]

Hi,

does anybody here on the list has experiences with Ubuntu 7.04 running
on soekris 5501 (http://www.soekris.com/net5501.html)?

I've made a PXE-installation on a CF-card and everything went well:
hdb1 - root-filesystem
hdb5 - swap

When I reboot the system everything went well (GRUB, ...) until it
wants to mount the root-filesystem, then I get the error:
ALERT! /dev/hdb1 does not exist. Dropping to a shell!

And a "BusyBox"-shell is opened.

If I start a rescue-system from PXE, it detects correctly the card.
Are there some special modules, which have to been loaded? Or is there
any other tip/trick/hint to start Ubuntu on a 5501?

By the way: An actual debian stable works out of the box.

Thanks in advance

Joerg Schoppet