Re: USB state change notification to user space
Jens Axboe (axboe@image.dk)
Sun, 5 Sep 1999 16:42:00 +0200
On Sat, Sep 04 1999, Johannes Erdfelt wrote:
> > A fourth possibility is some sort of signal, which makes sense in a way --
> > do we want the application to a) ask if there is a new device, b) wait for
> > a new device, or c) be notified that there is a new device? It wouldn't be
> > hard (I think) to write a callback function for the USB handler that an
> > application can register with (i.e. a signal). It seems to me that option
> > c) is the best, since it maps to the bus behavior best.
>
> Obviously, c) is the best, however it's difficult to do with signals.
> Allocating a signal specifically for this is kind of a waste. Are you
> thinking perhaps registering which singal should be raised by an ioctl?
>
> I was hoping to get something similar to c) with a poll interface. That
> way it can block in poll or poll the fd along with other fd's the
> program may need.
Someone recently mentioned doing poll on a proc entry, that might
be a solution here as well.
--
* Jens Axboe <axboe@image.dk>
* Linux CD-ROM Maintainer
* http://www.kernel.dk
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