[mythtv-users] No /dev/dvb devices

David Highley dhighley at highley-recommended.com
Mon Mar 19 18:47:33 UTC 2007

"R. G. Newbury wrote:"
> Michael T. Dean wrote:
> > On 03/18/2007 02:17 PM, Yeechang Lee wrote:
> >> Anthony Messina <amessina at messinet.com> says:
> >>   
> >>> i have the same issue as the previous poster.  since it worked for
> >>> you, would you mind sharing your /etc/modprobe.conf?
> >>>     
> >> I don't have any HD5000-related entries in my /etc/modprobe.conf.
> >>
> >>   
> > OP just needs to load cx88-dvb through his distro's supplied automatic 
> > module-loading scripts (i.e. /etc/modules or /etc/sysconfig/modules or 
> > /etc/modprobe/cx88-dvb or ... --ask on your distro's fora/mailing lists) 
> > or through an appropriate modprobe.conf entry (the first is easier than 
> > the second approach).  Note, also, that Linux 2.6.21 will likely fix the 
> > issue causing cx88-dvb to fail to load automatically, so doing things 
> > incorrectly (i.e. through auto-module-loading scripts) for such a short 
> > time is not a big deal.
> The problem here is that the new kernel is *too* good. Previously these 
> cards were not as well recognized, and at least in Fedora, the modprobe 
> entry prevailed. Then in 2.1.18 or 19, the kernel started recognizing 
> both the analog and digital sides, and loads a module, apparently at 
> random. This also seems to lock the modula, so that modprobe -r does not 
> work. This appears to happen BEFORE modprobe is run (Could be wrong but 
> I don't think so.)
> If the dvb side gets loaded first, the analog can be loaded later but 
> apparently, not the other way round.

That is not the way it worked for me with Fedora core 6. I had both the
analog side of the HD3000 card and the PVR 500 devices created and the
drivers loaded and then did a modprobe c88xx-dvb and all seemed to stay

> The answer is two-fold. First, blacklist at least the analaog module 
> (cx8800) in /etc/modrobe.d/blacklist. (This may be sufficient, but I am 
> not sure.)
> Secondly, unload the cx88xx module and then load the cx88_dvb module in 
> rc.local with 'modprobe -r cx88xx' and 'modprobe cx88_dvb'. The cx88xx 
> module is the base module, and removing it should remove all (any) 
> loaded cx88 modules. The cx88_dvb load will pull in the modules that it 
> depends on. You can see this with lsmod if you do this from a console 
> after booting.
> This should get you a /dev/dvb structure. If you want, you can load the 
> cx8800 after the cx88_dvb and get the matching /dev/videox entry.
> If you use this route, the /dev/video entry will follow any /dev/video 
> devices created by any 'modprobe ivtv' lines in modprobe.conf as you 
> arfe doing this AFTER modprobe.conf has been run.
> I have not totally confirmed what happens with mythbackend when the 
> /dev/dvb/adapater0 structure does not exist. I *think* that mythbackend 
> gets confused when it tries to probe for a DVB card. Accordingly I have 
> added 'service mythbackend restart' as the last line of my rc.local. 
> This ensures that mythbackend is started after ther cx88_dvb module is 
> loaded.
> Geoff
> -- 
>               R. Geoffrey Newbury			
>             Barrister and Solicitor
>        Suite 106, 150 Lakeshore Road West
>           Mississauga, Ontario, L5H 3R2
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