[elrepo] Announcement: EL5: Updated kmod-video4linux packages now available

[Phil Perry]

On 15/08/10 08:04, Nigel Jewell wrote:
>    Sorry - this time with the correct subject!
>
> Hi,
>
> I've just tried updating to
> kmod-video4linux-0.0-7.20100410.2.el5.elrepo.i686.rpm on CentOS 5.5 with
> kernel 2.6.18-194.11.1.el5 for use with cx88_dvb, cx8800, cx8802 and
> cx88xx modules (Hauppauge WinTV Nova-T PCI).  During installation it
> printed out a number of messages regarding missing ir_... symbols for
> each installed kernel.  Such as:
>
> ...
> WARNING:
> /lib/modules/2.6.18-194.8.1.el5/weak-updates/video4linux/cx88xx.ko needs
> unknown symbol ir_codes_pinnacle_pctv_hd
> WARNING:
> /lib/modules/2.6.18-194.8.1.el5/weak-updates/video4linux/cx88xx.ko needs
> unknown symbol ir_codes_powercolor_real_angel
> WARNING:
> /lib/modules/2.6.18-194.8.1.el5/weak-updates/video4linux/cx88xx.ko needs
> unknown symbol v4l2_i2c_new_probed_subdev
> WARNING:
> /lib/modules/2.6.18-194.8.1.el5/weak-updates/video4linux/cx88xx.ko needs
> unknown symbol ir_codes_iodata_bctv7e
> WARNING:
> /lib/modules/2.6.18-194.8.1.el5/weak-updates/video4linux/cx88xx.ko needs
> unknown symbol ir_codes_pixelview
> ...
>
> Upon reboot I found that the remote input no longer works on the
> Nova-T.  If I downgrade to
> kmod-video4linux-0.0-5.20090615.el5.elrepo.i686.rpm the remote starts to
> work again.
>
> Ideas?  Is anyone else seeing this?
>
> Kind Regards,
> Nige.

Hi Nigel,

Unfortunately missing symbols are not uncommon in the video4linux 
package. It is by no means an ideal solution, but rather an attempt at a 
one size fits all solution where if it works for you, great.

If the older 0.0-5.20090615 package works for you then I'd suggest you 
stick with that and maybe then add an excludes line to the yum config 
file for elrepo to prevent it being updated in future.

The longer explanation is that the v4l/DVB project aims to maintain a 
source tree that will compile against kernels from 2.6.17 upwards, which 
is great for EL5 as that is based on a 2.6.18 kernel. However, some 
modules sometimes introduce functionality that relies on features only 
present in later kernels which effectively breaks those modules when 
built on earlier kernels like that in EL5, so the source tree keeps a 
list of which modules require newer kernels (versions.txt) so they only 
get built against those kernels. Without looking into it in detail, it 
would appear what has happened in this case is that between the two 
versions, some feature(s) that requires a later kernel have been added 
to the modules that provide those missing symbols and thus they haven't 
been built. Thus the modules you are trying to use are looking for 
symbols provided by those missing modules (a bit like missing 
dependencies in RPM terms). I should really remove those modules from 
the package as they are effectively broken.

Thus kmod-video4linux is a bit of a double-edged sword. Whenever I 
update the package, some modules get fixed with later bug fixes and 
others break completely due to the reasons explained above. Consequently 
I don't update the package source code too often and as I said above 
it's probably best to just stick with the version that works for you.

Hope that helps.

Phil