Re: Order of DVB devices

[Andreas Besse <besse@motama.com>]

Kay Sievers wrote:
> On Tue, Jan 26, 2010 at 16:22, Greg KH <greg@kroah.com> wrote:
>   
>> On Tue, Jan 26, 2010 at 03:36:39PM +0100, Andreas Besse wrote:
>>     
>>> i have a system with multiple DVB cards of the same type and want to
>>> specify the order of the devices /dev/dvb/adapterX. The device plugged
>>> into the physical PCI slot 1 on the mainboard should be assigned to
>>> /dev/dvb/adapter0 and the card in PCI slot 2 should be assigned to
>>> /dev/dvb/adapter1.
>>>       
>
> We usually do not change kernel names, but create meaningful named
> symlinks to them. Stuff gets confused when /sys and /dev get
> out-of-sync.
>
>   
>>> In the following post
>>> http://thread.gmane.org/gmane.linux.kernel.pci/7446/focust67 there
>>> is mentioned that the order of the devices can be specified by using
>>> udev rules.
>>>       
>
> The order can usually only specified by unconditionally loading kernel
> driver modules in a defined order. This usually works fine for PCI
> devices, but can obviously not work if there are USB devices involved.
>
>   
>>> But how this can be done? Which information in /sys can be used to
>>> determine which DVB device is connected to which specific slot?
>>>       
>> Did you try the latest version of udev that has the persistant rules for
>> the v4l devices in it and look at the symlinks that are created to see
>> if they solve the problem for you?
>>     
>
> Looking at it now, I think we only do video4linux, not the DVB stuff,
> which has its own class. But it should be possible to implement a
> similar model for /dev/dvb/by-id, /dev/dvb/by-path without much
> problems. It's just, that nobody really cared so far.
>
> Thanks,
> Kay
>   

but how can these persistent rules solve the issue that the order of PCI Slots (PCI Bus IDs) is not deterministic and totally random determined at boot?

I think the udev rules only can use informations which are already available in /sys/ ?


regards,
Andreas Besse