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I'm having trouble trying to build a static binary of ffmpeg - I've got almost the whole build working, with the exception of two libs - libvorbis and libmp3lame.

These two libs are failing during ./configure, specifically on undefined functions from the math.h / libm:

libvorbis:

gcc -L/vol/build/lib -static -static-libstdc++ -static-libgcc -Wl,--as-needed -Wl,-z,noexecstack -I/vol/build/include -L/vol/build/lib -o /tmp/ffconf.UKKLGhCv/test /tmp/ffconf.UKKLGhCv/test.o -lvorbis -lm -logg -lstdc++ -lpthread -lexpat -ldl -lm --enable-libopencore-amrnb
/vol/build/lib/libvorbis.a(envelope.o): In function `_ve_envelope_init':
envelope.c:(.text+0x983): undefined reference to `_ZGVbN2v_sin'
envelope.c:(.text+0x9a9): undefined reference to `_ZGVbN2v_sin'
/vol/build/lib/libvorbis.a(lsp.o): In function `vorbis_lsp_to_curve':
lsp.c:(.text+0x650): undefined reference to `_ZGVbN2v_cos'
lsp.c:(.text+0x669): undefined reference to `_ZGVbN2v_cos'


libmp3lame:

gcc -L/vol/build/lib -static -static-libstdc++ -static-libgcc -Wl,--as-needed -Wl,-z,noexecstack -o /tmp/ffconf.dC4w1f5B/test /tmp/ffconf.dC4w1f5B/test.o -lmp3lame -lm -lstdc++ -lpthread -lexpat -ldl -lm --enable-libopencore-amrnb
/vol/build/lib/libmp3lame.a(psymodel.o): In function `init_s3_values':
psymodel.c:(.text+0x14d3): undefined reference to `_ZGVbN2v___exp_finite'
psymodel.c:(.text+0x14fa): undefined reference to `_ZGVbN2v___exp_finite'
/vol/build/lib/libmp3lame.a(psymodel.o): In function `psymodel_init':
psymodel.c:(.text+0xb62d): undefined reference to `_ZGVbN4vv___powf_finite'
psymodel.c:(.text+0xb677): undefined reference to `_ZGVbN4vv___powf_finite'
psymodel.c:(.text+0xb6c4): undefined reference to `_ZGVbN4vv___powf_finite'
psymodel.c:(.text+0xb711): undefined reference to `_ZGVbN4vv___powf_finite'
psymodel.c:(.text+0xb75b): undefined reference to `_ZGVbN4vv___powf_finite'
/vol/build/lib/libmp3lame.a(psymodel.o):psymodel.c:(.text+0xb7a2): more undefined references to `_ZGVbN4vv___powf_finite' follow
/vol/build/lib/libmp3lame.a(util.o): In function `fill_buffer':
util.c:(.text+0x28a6): undefined reference to `_ZGVbN2v_cos'
util.c:(.text+0x28cc): undefined reference to `_ZGVbN2v_cos'
util.c:(.text+0x28fb): undefined reference to `_ZGVbN2v_cos'
util.c:(.text+0x2921): undefined reference to `_ZGVbN2v_cos'
util.c:(.text+0x29cc): undefined reference to `_ZGVbN2v_sin'
util.c:(.text+0x29e8): undefined reference to `_ZGVbN2v_sin'

I can't figure out how to get these to sucessfully build. From what I understand, passing the -lm option should be enough, but apparently isn't. I checked for the presence of libm.a, which is located at /usr/lib/x86_64-linux-gnu/libm.a, I also tried to pass this directory in the -L flags, but no difference. The libs build fine when removing the -static flag, but the resulting binary is (duh) linked against libm.so.

Just in case, these are the flags I'm using to build the two libraries:

libvorbis:
./configure --prefix=${CMAKE_BINARY_DIR} --disable-shared --disable-oggtest

libmp3lame:
./configure --prefix=${CMAKE_BINARY_DIR} --disable-shared

I'd appreciate any pointers on how to fix or debug this any further.

Edit: after playing around with it some more, it seems like the libm is getting linked in - when I remove the -lm flag, I'm getting a ton more undefined references - sin, cos, __pow_finite, etc. When I put it back in, most of these go away and only those mangled symbols, such as _ZGVbN4vv___powf_finite and _ZGVbN2v_cos remain.

  • These symbols may be indeed missing from libm. You could verify with: readelf -s [path-to-libm] | grep [symname] – valiano May 27 '18 at 21:43
  • I may be off but it seems these symbols are not in libm - they don't demangle well. They may be part of the library itself. Check this link: https://dev.solus-project.com/file/data/7dedblvkcdk5kmw3ltvn/PHID-FILE-27qhoqo6wsubrntfj2xc/D1210.diff – valiano May 27 '18 at 21:47
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Well, I managed to solve it - googling the mangled symbols such as _ZGVbN2v_cos led me to this patch mentioning vector math, and in combination with ldd's output during dynamic linking mentioning libmvec, I realized that I might have to link that in as well.

For libmp3lame, it has to be linked in before libm:

gcc -L/vol/build/lib -static -o /tmp/ffconf.dC4w1f5B/test /tmp/ffconf.dC4w1f5B/test.o -lmp3lame -lmvec -lm

For libvorbis, the order of -lm and -lmvec doesn't matter, it builds either way.

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