[mythtv-users] Cards keep changing /dev/videoX devices...

Alan Calvert cal at graggrag.com
Sun Jun 17 03:14:42 UTC 2007


Nick Morrott wrote:
> On 15/06/07, R. G. Newbury <newbury at mandamus.org> wrote:
>> Alan Calvert wrote:
> 
>>> Yep, blacklisting everything and ordering the module loads explicitly in
>>> rc.local works, as does using a sledgehammer to crack a nut. Simply allocating
>>> video device numbers explicitly by means of module options also works.
>>>
>>> No desire for argument here, but some of the advice presented was simply false
>>> and misleading.
>> Nothing false. I'll put my hand up for being misleading about the module
>> being 'built into' the kernel.
>>
>> There are NO module options for the cx8800 which allow you to force it
>> to a specific video device, as there is for the ivtv driver. The only
>> control method is load order. So you have to know what is being loaded
> 
> What does the video_nr parameter for the cx8800 module do? modinfo cx8800 says
> 
> video_nr:video device numbers (array of int)

The module parameter to control cx8800 video device number allocation certainly does
exist, at least on current kernels. From the driver source, cx88-video.c 
  MODULE_PARM_DESC(video_nr,"video device numbers");
  MODULE_PARM_DESC(vbi_nr,"vbi device numbers");
  MODULE_PARM_DESC(radio_nr,"radio device numbers");
and 'modinfo cx8800' on my box returns 
  parm:           video_nr:video device numbers (array of int)

It explicitly sets the video device number(s) to be used by this module. Eg, with
just one card
  options cx8800 video_nr=7 radio_nr=7 vbi_nr=7
would result in /dev/video7, /dev/radio7, /dev/vbi7

With more than one card, the mysterious "array of int" comes in, eg, for three cards 
  options cx8800 video_nr=3,4,5 would result in explicit allocation of
/dev/video3, /dev/video4, /dev/video5 (every time!).

cheers.





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