CODEWITHSUNDEEP
c++cmakefilecmake
samprat
samprat

Reputation: 2214

CMake failed to compile in Linux

I am altering a CMake file which works on Windows to create a shared object in Linux.

The CMake file generates a makefile and when I did "make" on Linux, it built objects of foo libraries and it displays linking of all four libraries. For example:

Linking CXX static library lib_foo_d.a

and the final shared object

Linking CXX static library lib_scen_files_d.a

but at the end it displays

/usr/bin/ld: lib_foo3/lib_foo3_d.a(chap_alt_scence_defs.cpp.o):
relocation R_X86_64_32 against `.rodata' can not be used when making a shared object;
recompile with -fPIC
lib_foo3/lib_foo3_d.a: could not read symbols: Bad value
collect2: ld returned 1 exit status

I have tried a few other options, but no joy. Below is my CMakeLists.txt. Any help/criticism will be beneficial to me.

CMAKE_MINIMUM_REQUIRED( VERSION 2.8 )
CMAKE_POLICY( SET CMP0017 NEW ) 

PROJECT( disk_space_model )
INCLUDE( ../libs/helper_functions.cmake )
INCLUDE_THIRD_PARTY_SFC()
find_path_for_libs()

add_s_library( lib_foo1 )
add_s_library( lib_foo2) 
add_s_library( lib_foo3) 
add_s_library( lib_foo4) 

SET(    HEADER_FILES 
        stdafx.h
        INS_sensor_model.h
)

SET(    SOURCE_FILES
        Disk_space_model.cpp
)

SET(    RESOURCE_FILES 
        "Disk Space DLL.rc"
        resource.h
)

COMMON_SETUP()
set( LIB_FILES 
        lib_foo
        lib_foo1
        lib_foo3 
        lib_foo4 )

set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--export-all-symbols")
ADD_LIBRARY( disk_space_model SHARED ${SOURCE_FILES} ${HEADER_FILES} ${RESOURCE_FILES}  ${CMAKE_HELPER_FILES} )
SET_OUTPUT_DIRS( disk_space_model )
TARGET_LINK_LIBRARIES( disk_space_model ${LIB_FILES} )

Thanks ...

Upvotes: 0

Views: 1268

Answers (2)

Angew is no longer proud of SO
Angew is no longer proud of SO

Reputation: 171127

The linker is telling you what is wrong: the object is used in a shared library, but wasn't compiled with -fPIC. You need to add this flag somehow.

When using CMake 2.8.9 or later, you can simply set property POSITION_INDEPENDENT_CODE on the target(s) in question (the static libraries).

With prior versions of CMake, you need to add the flag directly to the targets' COMPILE_FLAGS properties (in the proper spelling for your compiler, probably just -fPIC).

Upvotes: 1

Slava
Slava

Reputation: 44248

In order to build shared library on Linux all sources, who's object files linked to it, must be compiled as relocatable (-fPIC option as linker complains). You try to link static libraries lib_foo1 lib_foo2 lib_foo3 etc into your shared library, and it fails. So possible solutions:

  • Build shared version (.so) of each library lib_foo1 lib_foo2 .. in addition to static one (.a)
  • Build static libraries with -fPIC parameter
  • Do not link static libraries to shared library, but link them to the app. This may not be possible if functions from static libraries are used in your shared lib.

Upvotes: 0

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