USB HDD boot panic (2.6.31)

["Ben Ryan" <ben@impulse.net.au>]

I've a question regarding boot from USB-attached IDE HDD under 2.6.31
(slackware/lilo).
Searches haven't shed much light on status or resolutions.
Booting from this device throws:


VFS: Cannot open root device "sda1" or unknown-block(0,0)
Please append a correct "root=" boot option; here are the available
partitions:
.
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown
block(0,)


I notice that there's no /dev/sd(x) devices listed as possible roots in the
error.
I've tried a kernel build with all relevant drivers inbuilt (not modules).
Tested on multiple machines with same result.
This issue seems to have some history, earlier kernels had patches written
for genhd.c (but I lack the skills to port them forward).
Discussion here:
http://lkml.indiana.edu/hypermail/linux/kernel/0405.0/0224.html

>From what I can gather the USB drivers aren't finished initialising before
the disks are enumerated and mapped to /dev.

Is this a known, current issue?
Does anyone have a patch that can help? If so, why isn't it mainlined?
(Please CC responses!)

Thanks
Ben