[FFmpeg-devel] [PATCH] Configure check for linux version when v4l demuxers are enabled

[Luca Abeni]

Hi,

Stefano Sabatini wrote:
> On date Friday 2008-11-14 08:04:50 +0100, Luca Abeni encoded:
>> Hi,
>>
>> Stefano Sabatini wrote:
>>> Hi, as in subject.
>> Why? I used v4l2 with linux 2.6.8 and similar kernels, and I never had
>> problems... Has something recently broken? If yes, we need to fix it, not
>> to disable useful features.
> 
> Hi, it's a linux headers bug, r14852 workarounded the problem for some
> kernel headers (2.6.22 at least, later kernels have been fixed
> upstream), but I think there is still some version which can't
> compile, maybe linux 2.6.21

I think it is not a linux bug, but a distribution bug: v4l2.c uses a
header from /usr/include, which is provided by the distribution (it
comes from a linux header, but it must be "sanitised" somehow). Some
distributions just copy headers from the kernel sources to /usr/include/linux,
causing this sort of bugs. But other distributions do the right thing.
I just tried compiling on an old debian machine (with a 2.6.8 kernel,
and headers in /usr/include which claim to come from a 2.6.0 kernel),
and everything compiled fine with the latest ffmpeg from subversion.

So, the check for LINUX_VERSION_CODE looks wrong, since it would
disable v4l2 compilation on a lot of machines that can actually compile
it without problems.


				Luca