[linux-dvb] Re: dvb/cvs: _SFBUF must be called? doh!

[Michael Hunold <hunold@convergence.de>]

Hello Guido,

> yepp, I did not try that simply for it seems to depend
> on overriding/replacing a few modules in the 2.4 kernel
> and it happens that I do have a bttv card as well.
If you use the "build-2.4" dir of the "dvb-kernel" CVS driver then the 
main Video4Linux-1 module "videodev.o" gets replaced by its 
Video4Linux-2 counterpart, which was backported from 2.5.

The device registering interface has been changed, so any old 2.4 
Video4Linux-1 drivers (ie. ov511 for USB webcams or the 2.4 bttv driver) 
will *not* work any more. You can load the drivers, but the kernel will 
oops on the first open.

For bttv users, however, there is hope for using dvb-kernel and bttv 
0.9.x at the same time. (see below)

> As of late, however, I learned that linux >= 2.4.19 has
> a V4L2 layer and all calls to V4L1 are mapped to the
> new api.
That is not true. A vanilla >= 2.4.19 kernel only has the Video4Linux-1 
interface build in.

There are, however, patches available from Gerd Knorr, to get his bttv 
0.9.x v4l2 driver to work under 2.4. Build instructions are here:
http://bytesex.org/v4l/build.html

You can either patch your kernel to have the same infrastructure as 2.5 
or you can build the V4L2 videodev.o module outside the kernel (like the 
"build-2.4" stuff does)

> What do you think, should it be possible to
> compile dvb-kernel drivers for linux >= 2.4.19 _without_
> replacing some of the original modules? 
Short answer: without modifications, no. Vanilla 2.4 kernels don't work 
with "dvb-kernel".

But the following should be possible: install bttv 0.9.x with all v4l2 
stuff, then compile dvb-kernel and only install the driver files, not 
the video4linux-2 stuff. It should be possible to run both bttv and dvb 
at the same time, using Video4Linux-2 -- although I haven't tried it.

> cheers,
> -- guido                                  http://google.de/search?q=guidod
I admit that this is currently very unsatisfying, but I'm glad that 
Video4Linux-2 has made it into the kernel finally.

At least I'm anticipating 2.6. But I fear that some applications will 
break because the compatibilty layer does not translate "correctly", ie. 
in the sense of the old bttv Video4Linux-1 driver, but that's another 
story...

CU
Michael.



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