Determining disk device and kicking GEOM when doing automatic mounting of umass devices

[Darren Pilgrim]

> -----Original Message-----
> From: "Dag-Erling Smørgrav" [mailto:des at des.no] 
> Sent: Friday, June 10, 2005 12:16 AM
> To: Darren Pilgrim
> Cc: freebsd-hackers at freebsd.org
> Subject: Re: Determining disk device and kicking GEOM when 
> doing automatic mounting of umass devices
> 
> 
> "Darren Pilgrim" <dmp at bitfreak.org> writes:
> > Attached as named above.  The logs show the da0 DISK class 
> in the GEOM
> > config, but no MBR class entry.
> 
> Take a closer look at geom-logs.  It shows a slew of CAM errors.
> There's something wrong with your fob, or possibly (but not likely)
> with the USB stack.

Except that after all those errors, it still mounts and "works fine".  Also,
trying to mount /dev/da0 does produce the MBR entry in the GEOM config:

1 MBR da0s1 255849984 512 i 0 o 2048 ty 11

It also produces a single "READ CAPACITY" CAM error like those produced when
the device attaches.  I also tested with a known-good USB zip drive plugged
into the same USB port.  It attached flawlessly: the console showed the
normal attach messages, GEOM config shows the appropriate MBR entry and
/dev/da0s4 is created.

So yeah I gueuss my fob is busted or funky.  The CAM errors are "just" the
drive saying there's no media present, so maybe the device doesn't support
the commands necessary to report disk capacity?  Is there a way to educate
CAM about this so the attach procedure doesn't break?

Why would the CAM errors prevent GEOM from creating the MBR geom during
attach but not when trying to mount /dev/da0?