Re: [PATCH] v4l: Introduce "stream" attribute for persistent video4linux device nodes

[Kees Cook <kees@xxxxxxxxxxx>]

Hi,

On Mon, Apr 28, 2008 at 12:26:55AM -0700, Brandon Philips wrote:
> Kees introduced a patch set last week that attempts to get stable device naming
> for v4l.  The set used a string attribute called function to allow udev to
> assemble a unique and stable path for device nodes.

Just a quick correction: that patch was 99% Kay's.  :)  I just jammed
stuff into individual drivers, and have been trying to run with it.
Thanks for cooking up an alternative we can poke at.  :)

> This patch is similar.  However, instead of a string an integer is used called
> "stream".  If the driver calls video_register_device in the same order every
> time it is loaded then we can end up with something like this with the right
> udev rules[1]:
> 
> /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video0
> /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video1
> /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video2

This would certainly work for me, and is much cleaner as far as not
needing to change each v4l device driver.  I do remember Kay objecting
to the idea of internal driver enumeration being exported to udev, but
I'll let him speak up if this method is a problem too.  :)

> Kees: I don't have a device that creates multiple device nodes.  Please
> test with ivtv.  :D

If Kay ACKs it, I will give it a spin -- I would expect it to run just
fine, though.  :)

-Kees

-- 
Kees Cook                                            @outflux.net

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