[Buildroot] [PATCH] ffmpeg: fix static linking build failure when using libavutil

[Giulio Benetti]

Il 11/09/2018 23:47, Giulio Benetti ha scritto:
> Hello,
> 
> Il 11/09/2018 22:42, Giulio Benetti ha scritto:
>> 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 generates libavutil.pc doesn't append -ldrm
>> after -lavutil.
>> Subsequentely if a package uses pkg-config and ffmpeg it will load
>> library dependencies from libavutil.pc without placing -ldrm at the tail.
>> Without this fix the only way is to workaround the problem directly in
>> the single package, like this:
>> https://github.com/buildroot/buildroot/commit/daf7dd87f4d93923df5e757fd43b3ad214a4a2ae 
>>
>>
>> Add patch to assure -ldrm comes after -lavutil when static linking.
>>
>> Fixes:
>> http://autobuild.buildroot.net/results/515/5152dcca58944cf732d09fba6e6c9af8a9243c75// 
>>
>> http://autobuild.buildroot.net/results/395/395be1a9cab824b82ef34c2ebd84d54243029b33// 
>>
>>
>> Signed-off-by: Giulio Benetti <giulio.benetti at micronovasrl.com>
>> ---
>>   ...igure-add-LIBDRM-to-extralibs_avutil.patch | 44 +++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>   create mode 100644 
>> package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch
>>
>> diff --git 
>> a/package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch 
>> b/package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch
>> new file mode 100644
>> index 0000000000..ae1f3423ae
>> --- /dev/null
>> +++ b/package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch
>> @@ -0,0 +1,44 @@
>> +From f4c9a7f55229d5275edb89c29ac9b18a737faf65 Mon Sep 17 00:00:00 2001
>> +From: Giulio Benetti <giulio.benetti at micronovasrl.com>
>> +Date: Tue, 11 Sep 2018 19:22:27 +0200
>> +Subject: [PATCH] configure: add LIBDRM to extralibs_avutil
>> +
>> +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.
>> +
>> +Add -ldrm to LIBDRM in case libdrm is enabled and add $LIBDRM to
>> +extralibs_avutil.
>> +
>> +Signed-off-by: Giulio Benetti <giulio.benetti at micronovasrl.com>
>> +---
>> + configure | 4 ++--
>> + 1 file changed, 2 insertions(+), 2 deletions(-)
>> +
>> +diff --git a/configure b/configure
>> +index 7377046d0a..7599fcc2bd 100755
>> +--- a/configure
>> ++++ b/configure
>> +@@ -5919,7 +5919,7 @@ enabled libcelt           && require libcelt 
>> celt/celt.h celt_decode -lcelt0 &&
>> +                                die "ERROR: libcelt must be installed 
>> and version must be >= 0.11.0."; }
>> + enabled libcaca           && require_pkg_config libcaca caca caca.h 
>> caca_create_canvas
>> + enabled libdc1394         && require_pkg_config libdc1394 
>> libdc1394-2 dc1394/dc1394.h dc1394_new
>> +-enabled libdrm            && require_pkg_config libdrm libdrm 
>> xf86drm.h drmGetVersion
>> ++enabled libdrm            && require_pkg_config libdrm libdrm 
>> xf86drm.h drmGetVersion && LIBDRM="-ldrm"
>> + enabled libfdk_aac        && { use_pkg_config libfdk_aac fdk-aac 
>> "fdk-aac/aacenc_lib.h" aacEncOpen ||
>> +                                { require libfdk_aac 
>> fdk-aac/aacenc_lib.h aacEncOpen -lfdk-aac &&
>> +                                  warn "using libfdk without 
>> pkg-config"; } }
>> +@@ -7096,7 +7096,7 @@ source_path=${source_path}
>> + LIBPREF=${LIBPREF}
>> + LIBSUF=${LIBSUF}
>> +
>> +-extralibs_avutil="$LIBRT $LIBM"
>> ++extralibs_avutil="$LIBDRM $LIBRT $LIBM"
>> + extralibs_avcodec="$extralibs"
>> + extralibs_avformat="$extralibs"
>> + extralibs_avdevice="$extralibs"
>> +--
>> +2.17.1
>> +
>>
> 
> The patch above has been upstreamed:
> https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5 
> 
> 

For completeness I point that the "Fixes:" are for "Motion" package.

Best regards
-- 
Giulio Benetti
CTO

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