[linux-dvb] semi-recent regressions in automatic loading of DVB modules

Andrew de Quincey adq_dvb at lidskialf.net
Thu Sep 7 05:26:21 CEST 2006

On Thursday 07 September 2006 01:46, Lincoln Dale wrote:
> g'day,
> i recently upgraded my mythtv backend machine to much faster hardware (dual
> core goodness).
> my system consists of 3 DVB-T single-tuner cards & 1 analog tuner.
> specifically:
>   1 x DvICO Fusion HDTV DVB-T1 (OEM version of T Plus;
>       requires: cx88, cx2388x, cx88-dvb, Zarlink MT352 frontend
>   1 x Twinham VisionPlus (bt878
>       requires: bt878, dvb-bt8xx, DST frontend
>   1 x AverMedia AV-771
>       requires: bt878, dvb-bt8xx, Zarlink MT352 frontend
>   1 x Hauppage WinTV (analog; bt848-based, requires bttv)
> due to the newness of the motherboard, i need to run a 'recent' (2.6.18rc5)
> kernel.  previously i used to run a 2.6.13 kernels without with whatever
> the stock dvb/v4l sync was as of 2.6.13.  (no need for tip-of-tree dvb).
> however, as of 2.6.18-rc5 kernel, dvb no longer functions correctly, so i
> need to run with tip-of-tree dvb.
> i've found that with tip of tree, while i can get everything to "work", i
> need to do some messing with modprobes in my rc.local file.  specifically,
> while udevstart/hotplug/udev identify the DVB cards correctly, they don't
> load the mt352 module.
> as such, what happens is that i get this in startup messages indicating
> cx88-dvb couldn't attach to the mt352 frontend as the mt352 module hadn't
> loaded, thus the DvICO Fusion HDTV DVB-T1 is inoperable:
> 	DVB: Unable to find symbol mt352_attach()
> 	cx88[0]: frontend initialization failed
> likewise, the DST frontend isn't automatically loaded/identified, so the
> Twinham VisionPlus card isn't operable either.  and dvb-bt8xx isn't
> automatically loaded, so the AverMedia AV-771 is also inoperable.
> by adding the following into my /etc/rc.d/rc.local script, i get all cards
> working:
> 	modprobe mt352
> 	rmmod cx88-dvb
> 	modprobe cx88-dvb
> 	modprobe dst
> 	modprobe dvb-bt8xx
> (i need to rmmod cx88-dvb since it was already loaded but mt352 wasn't)
> system was originally Fedora Core 3, much of it since updated to FC4 &
> FC5..
> should mt352/dst/dvb-bt8xx be loaded automatically?  is it up to
> /etc/modprobe.conf logic to do this?  or should the various dvb drivers be
> forcing the loading of these modules rather than reporting undefined
> symbols?

How are you installing the new kernel? DVB in 2.6.18 has a new feature, "dvb 
attach", designed to minimise the number of loaded modules. It this that is 
breaking. If for some reason, your depmod information is incorrect, it'll 
break, and wont be able to load the modules.

Note that it is also possible to turn dvb attach off (its in the dvb 
menuconfig submenu) if you don't care about this functionality... then it'll 
function as previously; i.e. it'll load all frontend modules supported by a 
driver, not just the ones actually needed.

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