[systemd-devel] udev: problem renaming deviceode for dvb-devices

[Dr. Thomas Bastian]

Am Samstag, den 23.06.2012, 14:41 +0200 schrieb Kay Sievers:
> On Sat, Jun 23, 2012 at 2:17 PM, Dr. Thomas Bastian <tbastian at gmx.net> wrote:
> >> Udev cannot rename kernel-created device nodes. These nodes are not
> >> created by udev, but by the kernel itself. Udev will not change them,
> >> just set permissions and ownership.
> >>
> >> Udev can add additional symlinks pointing to the kernel-created nodes.
> >> Just use SYMLINK+= instead of NAME=, like here:
> >>   http://cgit.freedesktop.org/systemd/systemd/tree/rules/60-persistent-v4l.rules
> >
> > thanks for your prompt reply. I understand your suggestion. But this
> > does not help me to bring 4 dvb-cards
> > (/dev/dvb/adapter0.../dev/dvb/adapter3) into the order needed for
> > adressing the proper hardware by different apps, because the necessary
> > symlinks have the same names as the kernel-given nodes (just another
> > order).
> >
> > Are there other possibilities to make the kernel establish the nodenames
> > based on hardware attributes rather then in the order of plugging the
> > hardware into the computer?
> 
> Not really. Kernel names are not predictable in that manner. They are
> simply unique numbers, no stability is guaranteed regarding
> parallelism or discovery order.
> 
> The tools which relay on a specific name should use the symlinks
> directly instead of looking at the plain kernel names.
> 
> Or they should be made aware to cope with different names at every
> bootup, and select the devices on properties they find at the device,
> instead of expecting the kernel's enumeration number to be stable.

Thanks for the information. I think, I gonna create a small shell script
that performs your suggested "name resolution".