[mythtv-users] No /dev/dvb devices
R. G. Newbury
newbury at mandamus.org
Mon Mar 19 18:27:46 UTC 2007
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.
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
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
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
R. Geoffrey Newbury
Barrister and Solicitor
Suite 106, 150 Lakeshore Road West
Mississauga, Ontario, L5H 3R2
newbury at mandamus.org
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