Re: [Libusb-devel] Still can't claim interface, "No such file or directory"

[Alan S. <st...@ro...>]

On Tue, 13 Oct 2009, Kustaa Nyholm wrote:

> Alan,
> 
> thanks for the offer to help further, I will try to come up  later today
> with those things you requested.
> 
> >From a quick googling it seems that enabling usbf_snoop should be trivial
> in Ubunty Hardy but usbmon seems like a bit more involved.

It shouldn't be.  I'm not familiar with Ubuntu, but you shouldn't need
to do anything more than:

	mount -t debugfs none /sys/kernel/debug
	modprobe usbmon

> A few thoughts however.
> 
> I doubt that usbmon will tell us much,  because to me it seems the my code
> fails before anything happens at usb packet level.

That's not necessarily true.  Things may happen at the USB packet level
without your awareness.  Remember, even though your program may not 
send any packets, the kernel definitely does.

> An other thought.
> 
> This page seems to provide instructions on setting up usbmon:
> 
> http://tjworld.net/wiki/Linux/Ubuntu/USBmonitoring
> 
> does that look it makes sense? It looks a bit involved but not
> too bad because I'm an Ubunty Hardy and I'm ready to walk the mile.

You don't need to mount a USB device filesystem.  You don't need any 
application programs.  In fact, most of what that page describes is 
stuff you don't need.

A better set of instructions can be found in the kernel source file 
Documentation/usb/usbmon.txt.

> However, this seems to involve significant changes to the system,
> including installation of USB device file system (not that I'm
> up to speed to understand what that is) and this sounds like something
> that may alter my system so that the problem disappears. Speaking
> of which, just a hunch, but could be this be the problem: according
> to the above link Ubuntu hardy does not have USB device file system,
> does libusb (0.1) depend on that?

You don't need to check any documentation.  Just check your computer.  
Does anything exist inside /proc/bus/usb or /dev/bus/usb?  If it does
then you've got what you need.

And if you don't have something that libusb depends on then your 
program wouldn't even work as well as it does.

> Ok, anyway I did a clean Ubuntu install first thing this morning,
> verified that I get permission error without the modifiaction
> to the default udev rule for usb devices and that after modification
> I get no such directory/file error on claim interface.  Interestingly,
> for some reason, even after clean install it does no appear as if
> usbhid grabbed the device anymore, as it did before. Perplexing,
> need to double check again by reinstalling once we figure out the
> no such directory.

Alan Stern