How to recompile with -fPIC
C++GccCompilationFfmpegFpicC++ Problem Overview
I was trying to reinstall my ffmpeg, following this guide, on my ARM Ubuntu machine. Unfortunately, when I compile a program which uses this lib I get the following failure:
/usr/bin/ld: /usr/local/lib/libavcodec.a(amrnbdec.o): relocation R_ARM_MOVW_ABS_NC against `a local symbol' can not be used when making a shared object; recompile with -fPIC
/usr/local/lib/libavcodec.a: could not read symbols: Bad value
collect2: ld returned 1 exit status
Now I would like to recompile it with -fPIC
like the compiler is suggesting but I have no idea how. Any help is appreciated.
C++ Solutions
Solution 1 - C++
Briefly, the error means that you can't use a static library to be linked w/ a dynamic one.
The correct way is to have a libavcodec
compiled into a .so
instead of .a
, so the other .so
library you are trying to build will link well.
The shortest way to do so is to add --enable-shared
at ./configure
options. Or even you may try to disable shared (or static) libraries at all... you choose what is suitable for you!
Solution 2 - C++
Have a look at this page.
you can try globally adding the flag using: export CXXFLAGS="$CXXFLAGS -fPIC"
Solution 3 - C++
After the configure step you probably have a makefile. Inside this makefile look for CFLAGS (or similar). puf -fPIC at the end and run make again. In other words -fPIC is a compiler option that has to be passed to the compiler somewhere.
Solution 4 - C++
I had this problem when building FFMPEG static libraries (e.g. libavcodec.a) for Android x86_64 target platform (using Android NDK clang). When statically linking with my library the problem occured although all FFMPEG C -> object files (*.o) were compiled with -fPIC compile option:
x86_64/libavcodec.a(h264_qpel_10bit.o):
requires dynamic R_X86_64_PC32 reloc against 'ff_pw_1023'
which may overflow at runtime; recompile with -fPIC
The problem occured only for libavcodec.a and libswscale.a.
Source of this problem is that FFMPEG has assembler optimizations for x86 platforms* e.g. the reported problem cause is in libavcodec/h264_qpel_10bit.asm -> h264_qpel_10bit.o.
When producing X86-64 bit static library (e.g. libavcodec.a) it looks like assembler files (e.g. libavcodec/h264_qpel_10bit.asm) uses some x86 (32bit) assembler commands which are incompatible when statically linking with x86-64 bit target library since they don't support required relocation type.
Possible solutions:
- compile all ffmpeg files with no assembler optimizations (for ffmpeg this is configure option: --disable-asm)
- produce dynamic libraries (e.g. libavcodec.so) and link them in your final library dynamically
I chose 1) and it solved the problem.
Reference: https://tecnocode.co.uk/2014/10/01/dynamic-relocs-runtime-overflows-and-fpic/
Solution 5 - C++
If you're building a shared library but need to link with static libavcodec add linker flags:
-Wl,-Bsymbolic
In case of cmake:
set(CMAKE_SHARED_LINKER_FLAGS "-Wl,-Bsymbolic")
Solution 6 - C++
I hit this same issue trying to install Dashcast on Centos 7. The fix was adding -fPIC
at the end of each of the CFLAGS in the x264 Makefile. Then I had to run make distclean
for both x264 and ffmpeg and rebuild.
Solution 7 - C++
In addirion to the good answers here, specifically Robert Lujo's.
I want to say in my case I've been deliberately trying to statically compile a version of ffmpeg. All the required dependencies and what else heretofore required, I've done static compilation.
When I ran ./configure
for the ffmpeg process I didnt notice --enable-shared
was on the commandline. Removing it and running ./configure
is only then I was able to compile correctly (All 56 mbs of an ffmpeg binary). Check that out as well if your intention is static compilation
Solution 8 - C++
Before compiling make sure that "rules.mk" file is included properly in Makefile or include it explicitly by:
"source rules.mk"