[mythtv-users] OT: Persistent DVB node

Michael T. Dean mtdean at thirdcontact.com
Wed Jul 18 23:24:05 UTC 2007

On 07/18/2007 05:01 PM, Nick Rout wrote:
> On Thu, July 19, 2007 6:52 am, Michael T. Dean wrote:
>> On 07/18/2007 02:28 PM, Razza wrote:
>>> Razza wrote on 15 July 2007 15:26:
>>>> Fantastic, Nick you are a genius! The symlink concept works on the DVB-
>>>> T card!
>>>> 2. Why can I only set up 7 dvb cards in Myth? (maybe 8 as I think the
>>>> counting starts from 0) as this will only allow for 4 sources using
>>>> this
>>>> method
>>>> 3. Is there any way to increase the number of DVB cards Myth will
>>>> accept?
>>> Not seen a definitive response on why you can only set 8 cards (0 to 7)
>>> in
>>> myth? and more importantly if you can increase this number!
>> The proper approach is to use udev to ensure each card type always gets
>> the same kernel number (and, funny enough, could be done using a script
>> very similar to the one you provided for "post-udev" linking, among
>> other approaches).
>> Nick's approach is a good approach for the user who doesn't care to
>> learn the proper usage of udev.  (Or for a person who doesn't feel like
>> teaching how udev is used on the list. :)
> I would have suggested looking harder at udev if the OP hadn't said that
> he had already consulted better minds than mine on the subject (he
> mentioned the udev mailing list and the dvb mailing list).

I wasn't trying to say your approach was a bad suggestion.  I just
figured you were in the second group of people I mentioned ("doesn't
feel like teaching how udev is used on the list").

> Perhaps you have an actual suggestion on how the OP could better write his
> udev rules.

In truth, I'm firmly in the second group of people (I'm trying to find
the time I need to do some things that are far more universally useful
for Myth rather than something useful to only one (or a few) people). 
My point, though, is that there are other ways of getting persistent
device naming for dvb devices, so if there is a limit in Myth of 8 DVB
devices, all 8 could be used on a properly configured system.

So changing the limit is only necessary for those who plan to use more
than 8 devices in a single system.  And, from that perspective, the
question shifts to, "Who has more than 8 slots in a system for DVB cards?"

And, if nothing else, there's always the slave backend approach for
increasing the number of cards the OP can use.  After all, the more
digital capture cards you put in the system, the noisier the signals get
and the dirtier the power, so the more likely to get recording

But, if the OP wants to provide patches, I'm sure they'll be considered
for inclusion.


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