Re: USB driver assignment with udev

[Scott James Remnant <scott@canonical.com>]

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On Wed, 2009-03-11 at 23:20 +0000, Steve Calfee wrote:

> I have a different situation, but a classic issue is if a user wants to
> have ub handle one device and usb-storage handle others. How can this be
> done? udev loads the driver, but the driver itself grabs the devices. The
> first module loaded will hog all the devices. USBIP will also sooner or
> later hit this problem, some devices might need to be local and some placed
> remotely.  Presumably separate drivers will be needed.
> 
That's simple.

ub includes an alias for the specific device (ie. by vendor/device id as
well as class).

usb-storage includes the generic classful alias.

ub appears before usb-storage in the kernel link order, and thus appears
first in /lib/modules/$(uname -r)/modules.order

So the kernel will try that module first if it's a built-in, and
modprobe will try load module first if not.


If you want to do more complicated runtime decisions, you can use the
bind/unbind interface.

Scott
-- 
Scott James Remnant
scott@canonical.com

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