* Mark <bts@bts.grml.org> [20070623 08:15]:

> Test results:  the modules are not the problem.  We blacklisted each one in the
> diff list, but all tests gave identical results.  The USB disk was not detected
> properly.

Ok.

> But good news, a different test isolated better.  Here is the full USB system
> that grml 1.0 CD-ROM botches:

> PC --> USB 2.0 Port A --> USB 2.0 Disk
>      --> USB 2.0 Port B --> USB 2.0 Hub --> USB Scanner

> Removing the USB cable to the hub makes grml 1.0 CD-ROM recognize the USB Disk
> (with udev on, no special boot options).

> So the bug happens only with the hub plugged in.  Then grml 1.0 fails to see the
> USB Disk.  If the hub is unplugged, udev works, and grml sees the USB Disk.

Ok, thanks.

> grml 2.6.18 handles everything plugged in, very reliably.  So it is not a USB
> hardware glitch.  In fact the hub is practically brand new.

JFTR: Because hardware is new it does not mean that it's ok. ;)
You can have brand new hardware which just ignores parts of the
specification and therefore does not work on operating systems
having some more checks inside the code than others. (Yes, I
explored such issues already on my own.)

> Let us know what other data you want.  We're pretty convinved it's a udev
> hotplugging issue - maybe the timeout is too short? - udev in 2.6.20.11 is
> having problems with USB hubs.

> We can try the 'grml nousb nousb2' test tomorrow if it will help.

As I've written already: this might be a regression in the kernel as
well. So give 2.6.21-grml a shot or wait until a live grml with
2.6.22-grml is available. If we have the USB hub problem with
>=2.6.21 on your system as well we can continue debugging it in further
detail.

thx && regards,
-mika-