RE: usb-mount (hotplug + desktop hooks)

[Gary_Lerhaupt@Dell.com]

I checked /proc/scsi/usb-storage-0 after plugging in my flashcard reader.
In my particular case, the device returned a Serial Number of "None" but did
return what appeared to be an interesting and unique GUID value.  Michael,
did you comments about the non-uniqueness of serial numbers also extend to
GUIDs?  

If not, I could immediately add USB GUIDs where applicable within devlabel
and then automounting would be simple.  Do your two USB storage devices
return different (yet consistent) GUID values?

Gary
devlabel: www.domsch.com/linux/devlabel

-----Original Message-----
From: Michael Hamilton [mailto:michael@actrix.gen.nz]
Sent: Wednesday, November 06, 2002 3:21 AM
To: a_ajay_sr@yahoo.com; Gary_Lerhaupt@exchange.dell.com
Cc: Linux-hotplug-devel@lists.sourceforge.net
Subject: Re: usb-mount (hotplug + desktop hooks)

No, the serial need not be something burned into the device.  
The device I have makes up a serial number on the fly.
Each time it is inserted it appends its position on the bus onto 
the end of the vendor and product id - so the serial is 
vendor-product-bus-location.  The next time I plug it
in the bus-location may differ, so the serial will differ.
This sums it up and adds a scary note on uniqeness:

Note, that although Matt states that only a few manufacturers have
done this, their chipsets may be turning up in many products.
There are several products that identify themselves as the same as
mine, but they're different kinds of devices: fixed usb-drives, card
readers, etc, all sold under different brands. 

On Wed, 06 Nov 2002 17:23, Ajay wrote:
> ...
> > The only way I found
> > to clear this
> > up is to unload the usb-storage module.
>
> Also, the fact is that /dev/sda, etc. are only
> 'relative labels' - i.e. if you had plugged in a
> device before the one you're using, _that_ would have
> been /dev/sda and your device /dev/sdb, even if the
> serial hasn't changed (this after unloading - loading
> the usb-storage module).
> ...

Yes, I understand this. The point I was trying to make was
that after I unplug the device, the /dev/sdX remains allocated 
forever. This is because the serial keeps changing.
And, because the serial keeps changing, I keep using more and more 
/dev/sdX entries.  And, as stated, the only way to clear them 
is to either reboot, or get to a point where usb-storage 
can be unloaded - that is, unplug all storage devices and 
then depmod -r usb-storage.  This is exacty what my current
solutions does - if it sees that there are no devices left
on the bus, it removes the module.

I was rather surprised by all this - it's a nifty device and
a great way to transport stuff to and from client sites, but
looking at how it fits into exiting ideas on mouting and 
partitioning was a real education (see 
http://users.actrix.co.nz/michael/usbmount.html for details)

Michael







-------------------------------------------------------
This sf.net email is sponsored by: See the NEW Palm 
Tungsten T handheld. Power & Color in a compact size!
http://ads.sourceforge.net/cgi-bin/redirect.pl?palm0001en
_______________________________________________
Linux-hotplug-devel mailing list  http://linux-hotplug.sourceforge.net
Linux-hotplug-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel