[FFmpeg-devel] [PATCH] configure: add LIBDRM to extralibs_avutil

Giulio Benetti giulio.benetti at micronovasrl.com
Tue Sep 11 23:59:54 EEST 2018


Il 11/09/2018 22:49, James Almer ha scritto:
> On 9/11/2018 5:29 PM, Giulio Benetti wrote:
>> When static linking programs using ffmpeg libraries, if linking against
>> libavutil, -ldrm is listed before -lavutil. This leads to linking failure
>> due to undefined reference of drmGetVersion() and drmFreeVersion().
>> This is why when pkg-config create libavutil.pc doesn't append -ldrm
>> after -lavutil.
>> Create LIBDRM=-ldrm in case libdrm is enabled and add $LIBDRM to
>> extralibs_avutil.
> I'm not sure i understand. libdrm is already added to avutil extralibs,
> seeing it's listed in the "avutil_suggest" line in configure. I see it's
> also added to avdevice if kmsgrab_indev is enabled.
> The -ldrm ldflag, assuming the libdrm pkg-config file is correct, should
> be in $avutil_extralibs when configure dumps it into extralibs_avutil
> for the purpose of creating libavutil.pc.

I point you a build failure, so it should be more clear.
I did my best to explain on commit log, but it wasn't easy.


In that case .configure file is different but the point is the same.

At the end of the log you can see that -ldrm is yes present, but it 
comes too early respect to -lavutil.
This situation is valid only in the case you link *statically*.
For dynamic linking there's no problem at all.

Thanks and
Best regards
Giulio Benetti

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