[linux-dvb] RFC: remove support from v4l-dvb for kernels < 2.6.16

Hans Verkuil hverkuil at xs4all.nl
Thu Jul 3 23:52:54 CEST 2008


RFC: remove support from v4l-dvb for kernels < 2.6.16

After spending some time trying to get v4l-dvb to compile on older 
kernels I discovered that:

- it is OK for kernels >= 2.6.19

- it does not compile at the moment for kernels >= 2.6.16 and < 2.6.19, 
but that this can be fixed.

- that it can be made to compile for kernels >= 2.6.12 and < 2.6.16, 
although quite a few drivers had to be disabled and looking at the type 
of compile warnings emitted the result would likely crash, especially 
the closer one gets to 2.6.12.

- that I no longer can compile against older kernels since gcc-4.1.2 no 
longer accepts some constructions used in those kernel sources.

I propose that we remove the support for kernels < 2.6.16. Kernel 2.6.16 
is the kernel that's being maintained long-term, so that makes it a 
good starting point. I know that I get the occasional question about 
kernel 2v4l/em28xx-audio.c.6.18, so that definitely has to be supported 
by v4l-dvb, and the differences between 2.6.18 and 2.6.16 are minor, so 
extending the support to 2.6.16 is not a problem.

I did a few scans and of the approximately 932 KERNEL_VERSION checks 
only 268 remain if we drop support for anything below 2.6.26. That's a 
major cleanup.

Since it is now simply broken for anything below 2.6.19 I think it is a 
good solution to on the one hand do a major cleanup at the expense of 
making it unlikely that we will ever support kernels below 2.6.16, and 
on the other hand at least start to support 2.6.16 and up.

I can set up a test build to periodically test if v4l-dvb still compiles 
on these older kernels (although currently I can only test on a 32 bit 
Intel platform).

I'm also willing to do the clean up (I've always liked throwing away 
code!).

In the long term we should probably review the minimum kernel 
requirements on a yearly basis and see if we should move it up. 
Especially major changes in the way the kernel handles device structs 
can be a big pain to maintain. That's currently the main reason for the 
breakage of kernels < 2.6.19.

Regards,

	Hans Verkuil



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