Re: udev: attributes rules to identical devices

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Jan 15, 2014 at 02:15:43PM +0000, Theo wrote:
> Hello everybody, 
> 
> I am working with Kubuntu 13.10. 
> I need to assign permanent names to some modems that I am working with. 
> This would be possible by creating a rule in /etc/udev/rules.d/ and defining 
> a symlink, something like this:
> 
> KERNEL="ttyUSB[0-9]*", ATTRS{serial}="0000:00:1d.0", SYMLINK="Modem0"
> 
> The problem is that all these modems have the same serial, so I cannot 
> distinguish them and cannot assign a different symlink to each one. 
> 
> If it can help, the output of lsusb with two modems connected is this:
>  
> Bus 006 Device 002: ID 0403:6001 Future Technology Devices International, Ltd 
> FT232 USB-Serial (UART) IC
> Bus 005 Device 002: ID 0403:6001 Future Technology Devices International, Ltd 
> FT232 USB-Serial (UART) IC

You should already have some links in /dev/serial/ right?  Why not use
those?

Otherwise you are going to have to use the USB path, but if USB
enumerates them in a different order next time you boot, the paths are
going to be different.  You should bug your vendor about putting unique
serial numbers in them, that's the only "real" way to do this correctly,
sorry.

Hope this helps,

greg k-h