Re: Which node has the device been bound to?

[Oliver Neukum <Oliver.Neukum@lrz.uni-muenchen.de>]

Am Mittwoch, 29. Mai 2002 12:23 schrieb Kim Deokhwan:
> Within a USB policy agent script, can we tell precisely which node the
> device has been bound to?  According to
> Documentation/usb/usb-serial.txt:
>
>   When the device is connected and recognized by the driver, the driver
>   will print to the system log, which node(s) the device has been bound
>   to.
>
> But the log message is too succint:
>
>   May 27 10:51:11 localhost kernel: usbserial.c: Compaq iPAQ converter
>   now attached to ttyUSB0 (or usb/tts/0 for devfs)
>
> In case of one iPAQ, we can find the relevant log entry by grepping the
> LAST matched line.  But if two iPAQs are attached nearly at the same
> time, the last matched line may not be the relevant entry because
> context switching may happen between two agent scripts.
>
> Do you have any method that can solve it?

At present I am afraid not.
This is just the tip of the iceberg. Basically, even if you had that
type of information, you cannot be sure that it stays valid
while the script is running.

You might have a look at driverfs currently under development in the
2.5 tree. It could help.

In addition the hotplug script may be called without a loaded driver
and there'll be no notification (outside devfs) if a driver binds to a device
after the device is plugged in.

	Regards
		Oliver


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