Re: Query regarding alloc_chrdev_region()

[Greg KH <greg@kroah.com>]

On Fri, Mar 30, 2007 at 08:06:23AM +0530, Rajat Jain wrote:
> Hi,
> 
> >> I was wondering that while using dynamic device numner allocation, can
> >> we ever have a scenario like following (using alloc_chrdev_region):
> >>
> >> 1) Char Driver A is hooked on Major num X, minor numbers 0-10
> >> 2) Char Driver B is hooked on (same) Major num X, minor numbers 11-20
> 
> So the above is actually possible?

Yes, once you have a major number, you can separate out the minor
numbers how ever you wish to.

> >> If yes, how will the userland get to know about the dynamically
> >> allocated range (needed to create device nodes), since /proc/devices
> >> only shows major numbers?
> >
> >Through the exporting of this information in sysfs by using the
> >device_create() call that you are required to do in order to have your
> >device show up properly there :)
> 
> Is that taken care by cdev_add() itself?

Nope, not at all.

thanks,

greg k-h
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