Re: cold plugging

[Kay Sievers <kay.sievers@vrfy.org>]

On Sat, Jan 14, 2006 at 06:10:48PM +0500, Alexander E. Patrakov wrote:
> Kay Sievers wrote:
> >On Sat, Jan 14, 2006 at 10:00:29AM +0500, Alexander E. Patrakov wrote:
> >>Greg KH wrote:
> >>
> >>>Why does USB take longer for you?  What is taking such a long time?
> >>>
> >>The /dev/bus/usb/... node for my Mustek Plug-N-Scan 1200 UB Plus scanner.
> >
> >It's the simplest way to wait for all events. Depending how you handle
> >dependencies/checkoints on bootup, it may be sudfficient if all localfs
> >devices have appeared and you can let the other events finish 
> >asynchronously.
> > 
> >
> Thanks, but you probably missed the point. Your loop does NOT wait for 
> all events. I think that in my case the following happens:
> 
> 1) The script creates an empty /dev/.udev/queue directory
> 2) The script causes the kernel to emit uevents
> 3) udevd gets those uevents, and reacts upon them. This reaction 
> involves, among other things, making device nodes and calling 
> /sbin/modprobe to load new drivers.
> 4) Those drivers are bound to devices by the kernel, this produces new 
> uevents, go to (3).
> 5) When the internal queue of udevd becomes empty, it removes the 
> /dev/.udev/queue directory and the loop exits.
> 
> The problem is that some modules take longer than 0.1s to detect their 
> hardware, so there is a period of time longer than 0.1s with the empty 
> udevd queue, after which new uevents arrive.

Which modprobe for which module is it, that returns before events for
the devices are generated?

Kay


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