Hi Alan,

>> Will try and report back, thanks. I've bisected it down in the meantime
>> to a change from 2.6.31.6 to 2.6.32.6. Interestingly, this is very much
>> the same time when the udev userland changed. It works with 2.6.31.6 old
>> udev, but not with 2.6.36.2, new udev.
>
> Can't you use the new udev with the old kernel?

Nope. udevd refuses to start and says that it requires at least 2.6.32, 
which means that apparently something changed in the kernel-userland 
interface in 2.6.32. Thus, my conclusion that there's probably something 
nasty going on in userland with udev.

Here's what I got: "messages" - output from /var/log/messages. Note that 
the mount hangs exactly at the SCSI 2A command you see there, then tries 
to reset the device after probably 20 seconds or so.

"udevmonitor" - what "udevadm monitor" generated and hence what udev got 
from the kernel.

"usbdevices" what I got from "lsusb". The interesting USB busses are 3 - 
the ehci chip, and 4, its ohci companion. The rest is the legacy uhci of 
the board.

"usb-device-3" that's what I got from /sys/kernel/debug/usb/usbmon/3u, 
i.e. the ehci bus.

The corresponding ohci bus (#4) remains empty, no debug output from there.

Hope you'll find some time to look into this riddle. If you need 
anything more to hunt it down, please let me know.

Thanks,
	Thomas