ffmpeg: fix static linking build failure when using libavutil

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 <[email protected]>

---
  ...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

package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch new file +34 -0

new file mode 100644
index 0000000000..ae1f3423ae
@@ -0,0 +1,44 @@
+From f4c9a7f55229d5275edb89c29ac9b18a737faf65 Mon Sep 17 00:00:00 2001
+From: Giulio Benetti <[email protected]>
+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 $LIBDRM to
+extralibs_avutil.
+
+Signed-off-by: Giulio Benetti <[email protected]>
+---
+ configure | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/configure b/configure
+index 7377046d0a..7599fcc2bd 100755
+--- a/configure
++++ b/configure
+@@ -5919,7 +5919,7 @@ enabled libcelt           && require libcelt celt/celt.h celt_decode -lcelt0 &&
+                                die "ERROR: libcelt must be installed and version must be >= 0.11.0."; }
+ enabled libcaca           && require_pkg_config libcaca caca caca.h caca_create_canvas
+ enabled libdc1394         && require_pkg_config libdc1394 libdc1394-2 dc1394/dc1394.h dc1394_new
+-enabled libdrm            && require_pkg_config libdrm libdrm xf86drm.h drmGetVersion
++enabled libdrm            && require_pkg_config libdrm libdrm xf86drm.h drmGetVersion && LIBDRM="-ldrm"
+ enabled libfdk_aac        && { use_pkg_config libfdk_aac fdk-aac "fdk-aac/aacenc_lib.h" aacEncOpen ||
+                                { require libfdk_aac fdk-aac/aacenc_lib.h aacEncOpen -lfdk-aac &&
+                                  warn "using libfdk without pkg-config"; } }
+@@ -7096,7 +7096,7 @@ source_path=${source_path}
+ LIBPREF=${LIBPREF}

Hello,

Il 11/09/2018 22:42, Giulio Benetti ha scritto:

Quoted 85 lines

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 <[email protected]>

---
? ...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

(quoted diff) +0 -0

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

package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch new file +7 -0

@@ -0,0 +1,44 @@
+From f4c9a7f55229d5275edb89c29ac9b18a737faf65 Mon Sep 17 00:00:00 2001
+From: Giulio Benetti <[email protected]>
+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

package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch new file +17 -0

+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 <[email protected]>
+---
+ 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"

Quoted 5 lines

+ extralibs_avdevice="$extralibs"
+--
+2.17.1
+

The patch above has been upstreamed:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

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.

Hello Giulio,

Quoted 2 lines · Giulio Benetti

When static linking programs using ffmpeg libraries, if linking against libavutil, -ldrm is listed before -lavutil.

I think this is not relevant in the explanation, the fact that motion links with libdrm directly is independent from the fact that ffmpeg may use libdrm internally.

Quoted 3 lines

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

pkg-config does not generate .pc files, it only reads them.

Quoted 3 lines

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.

Well, the fact that it's at the tail is a detail, but the main problem is that the libavutil.pc file does not list *at all* the dependency on libdrm.

Quoted 2 lines

Without this fix the only way is to workaround the problem directly in the single package, like this:

"the single package" is not very clear, I would say "in each package using ffmpeg".

Quoted 3 lines

https://github.com/buildroot/buildroot/commit/daf7dd87f4d93923df5e757fd43b3ad214a4a2ae

Add patch to assure -ldrm comes after -lavutil when static linking.

No, that's not what the patch does. The patch ensures that libavutil.pc tells pkg-config that linking against libdrm is needed.

package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch line 38

Quoted 10 lines

++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 ||

package/ffmpeg/0002-configure-add-LIBDRM-to-extralibs_avutil.patch new file +8 -0

+                                { 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"

This fix is in fact not the most correct one. Indeed, it does the following change to libavutil.pc:

(quoted diff) +1 -1

-Libs: -L${libdir}  -lavutil -lm
+Libs: -L${libdir}  -lavutil -ldrm -lm

but the proper change would be:

  Libs: -L${libdir}  -lavutil -lm

(quoted diff) +1 -1

-Libs.private:
+Libs.private: -ldrm

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

Quoted 3 lines

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

You've explained me it very well, but by now FFmpeg upstreamed my patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

So, do I rework and resubmit to them or can I re-create a patch for BR with what you've pointed me above?

Hello,

Quoted 4 lines · Giulio Benetti

Quoted 3 lines

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

Quoted 5 lines

You've explained me it very well, but by now FFmpeg upstreamed my patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

So, do I rework and resubmit to them or can I re-create a patch for BR with what you've pointed me above?

Both ? :-)

Il 24/09/2018 13:09, Thomas Petazzoni ha scritto:

Quoted 13 lines

Hello,

Quoted 9 lines · Giulio Benetti

Quoted 3 lines

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

You've explained me it very well, but by now FFmpeg upstreamed my patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

So, do I rework and resubmit to them or can I re-create a patch for BR with what you've pointed me above?

Quoted 9 lines

Quoted 9 lines

Quoted 9 lines

Quoted 3 lines

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

You've explained me it very well, but by now FFmpeg upstreamed my patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

So, do I rework and resubmit to them or can I re-create a patch for BR with what you've pointed me above?

I've missed one thing to ask you about ffmpeg:
Can I still use this hack:
https://git.ffmpeg.org/gitweb/ffmpeg.git/blobdiff/bc2301429e9c779237e43acf913331af018211f2..c50dc77ac708e98d02da7c422a6b9cbf9f565aa5:/configure

to obtain if -ldrm is used and then add it to Libs.private like this:
Libs.private: -ldrm

as you've pointed me.

Or there is something that makes it simpler and better?

Hello,

Quoted 16 lines · Giulio Benetti

Quoted 9 lines

Quoted 9 lines

Quoted 9 lines

Quoted 3 lines

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

You've explained me it very well, but by now FFmpeg upstreamed my patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

So, do I rework and resubmit to them or can I re-create a patch for BR with what you've pointed me above?

I've missed one thing to ask you about ffmpeg:
Can I still use this hack:
https://git.ffmpeg.org/gitweb/ffmpeg.git/blobdiff/bc2301429e9c779237e43acf913331af018211f2..c50dc77ac708e98d02da7c422a6b9cbf9f565aa5:/configure

to obtain if -ldrm is used and then add it to Libs.private like this:
Libs.private: -ldrm

Quoted 3 lines

as you've pointed me.

Or there is something that makes it simpler and better?

I'm not sure what "hack" you're talking about here. My only point it is only needed to link "indirect" libraries when static linking, and therefore such "indirect" libraries should be listed in Libs.private and not Libs in pkg-config files.

Hello,

Il 12/10/2018 21:50, Thomas Petazzoni ha scritto:

Quoted 28 lines

Hello,

Quoted 13 lines · Giulio Benetti

Quoted 9 lines

Quoted 9 lines

Quoted 9 lines

Quoted 3 lines

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

You've explained me it very well, but by now FFmpeg upstreamed my patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

So, do I rework and resubmit to them or can I re-create a patch for BR with what you've pointed me above?

I've missed one thing to ask you about ffmpeg:
Can I still use this hack:
https://git.ffmpeg.org/gitweb/ffmpeg.git/blobdiff/bc2301429e9c779237e43acf913331af018211f2..c50dc77ac708e98d02da7c422a6b9cbf9f565aa5:/configure

Quoted 6 lines

to obtain if -ldrm is used and then add it to Libs.private like this:
Libs.private: -ldrm

as you've pointed me.

Or there is something that makes it simpler and better?

I'm not sure what "hack" you're talking about here. My only point it is only needed to link "indirect" libraries when static linking, and therefore such "indirect" libraries should be listed in Libs.private and not Libs in pkg-config files.

Hello Thomas,

Il 12/10/2018 22:54, Giulio Benetti ha scritto:

Quoted 31 lines

Hello,

Il 12/10/2018 21:50, Thomas Petazzoni ha scritto:

Quoted 28 lines

Hello,

Quoted 13 lines · Giulio Benetti

Quoted 9 lines

Quoted 9 lines

Quoted 9 lines

Quoted 3 lines

Indeed, when we're dynamic linking, there is no need to link consumers of libavutil with libdrm. It is only when we're statically linking that it should be done. And that's exactly what Libs vs. Libs.private is for.

You've explained me it very well, but by now FFmpeg upstreamed my patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

So, do I rework and resubmit to them or can I re-create a patch for BR with what you've pointed me above?

I've missed one thing to ask you about ffmpeg:
Can I still use this hack:
https://git.ffmpeg.org/gitweb/ffmpeg.git/blobdiff/bc2301429e9c779237e43acf913331af018211f2..c50dc77ac708e98d02da7c422a6b9cbf9f565aa5:/configure

Quoted 6 lines

to obtain if -ldrm is used and then add it to Libs.private like this:
Libs.private: -ldrm

as you've pointed me.

Or there is something that makes it simpler and better?

I'm not sure what "hack" you're talking about here. My only point it is only needed to link "indirect" libraries when static linking, and therefore such "indirect" libraries should be listed in Libs.private and not Libs in pkg-config files.

I've worked this out, but I have a question:
Since FFMpeg upstreamed my previous wrong patch:
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/c50dc77ac708e98d02da7c422a6b9cbf9f565aa5

now I would submit another patch to FFMpeg to correct Libs vs Libs.private problem.

Here is the new patch:
https://github.com/giuliobenetti/FFmpeg/commit/d682f418b7912b9d9e1818aefa61a51a2868fb20

So:
do I have to submit to Buildroot a patch containing both patches? Or only one that merge both patches together even if it's not upstreamable?

If a package tries to static link with libavutil it fails due to the lack of libavutil private dependencies in libavutil.pc (-ldrm in this case).

Add patch to:
- Check if libdrm is present.
- Add it to Libs.private: in libavutil.pc if present.

Fixes:
http://autobuild.buildroot.net/results/766/766de487f394490df8c712652ac364ebb4a3ab14/
http://autobuild.buildroot.net/results/041/041e29dfddb2da3309ac7d34a576c60c5a75fe4d/
http://autobuild.buildroot.net/results/780/78061b61cfe3f42554a475c048d54dacacfe11d5/
http://autobuild.buildroot.net/results/275/275e4e0030d26c029085b408cfb272d5633969c6/
http://autobuild.buildroot.net/results/515/5152dcca58944cf732d09fba6e6c9af8a9243c75/
http://autobuild.buildroot.net/results/395/395be1a9cab824b82ef34c2ebd84d54243029b33/

Signed-off-by Giulio Benetti <[email protected]>

---