For example, I have libprofiler.so file. How can I get name of this shared object like this:
getname /usr/lib/libprofiler.so
I want to do it because it is required for CMakeLists.txt in
target_link_libraries(MyProject name_of_library)
Do the following steps to link an existing lib to your target:
Inform you which lib do you need: here profiler.
Build the name of the lib. CMake does not really needs this but it is worth to know: Example on Unix/Linux lib + NAME + [.so|.a] [VERSION]. Here: libprofiler.so.
In your CMakeLists.txt:
find_library(LIB_PROFILER NAMES profiler libprofiler.so libprofiler.so.V123)
add_executable(MyApp ${SOURCES})
target_link_libraries(MyApp ${LIB_PROFILER})
The code above tries to find a lib and checks the following name profiler, libprofiler.so and libprofiler.so.V123. If found, the variable LIB_PROFILER points to the lib file.
Use the variable as one of the files linked to your target.
In your code, you also missed the ${} around the variable.
Related
we are working on an embedded project in C/C++ and currently some special needs appeared. Background is there are two compiled libraries which define the same symbols. The compiler allows to create relocatable output modules (with partial linking) and to hide symbols for other compilation units when linking. This also means the output module does not need to have all the symbols defined, this will be done in the final linking. Compiler used is TI LTS1.3.0. I will link directly to the relocatable-section of the manual: https://software-dl.ti.com/codegen/docs/tiarmclang/rel1_3_0_LTS/compiler_manual/linker_description/04_linker_options/linker-output-options.html#stdz0756429
The other part of the project is hardly built on CMake with static libraries which are linked against each other via target_link_libraries.
To get this working I created an "add_executable"-target for each of those both output modules with the same symbols. To those I pass the static-libraries by CMake and get the linked with target_link_libraries.
But now I have a problem. All contents of the static libraries are compiled in each of those output modules. This is unwanted behaviour since as said the final linking does the job of linking the missing stuff - so the static-libraries - to it. This should be done with another add_executable command via CMake as well.
using the target include directories property is not suitable since it only adds the include directories of the given target itself but not of the target the target will include and link against.
So e.g. if you have (pseudo code):
#library A
function( create_libA )
add_library( libA src/A.c )
target_include_directories( libA PUBLIC /inc ) #contains A.h
endfunction()
#library B. different location
function( create_libB LIBA )
add_library( libB src/B.c )
target_link_libraries( libB PUBLIC ${LIBA} )
target_include_directories( libB PUBLIC /inc ) #contains B.h
endfunction()
#target output module with partial linking. Only should link and compile LIBTOBELINKEDIN, not libB. different location.
function( build_part_module LIBB LIBTOBELINKEDIN )
add_executable( outputModuleA src/func.c ) #func.c does include A.h
#following would cause libA and libB also to be compiled and linked in the output due to transitive stuff as I understood, which is unwanted.
target_link_libraries( outputModuleA PUBLIC ${LIBB} ${LIBTOBELINKEDIN} )
#trying this
get_target_property(libBInc ${LIBB} INTERFACE_INCLUDE_DIRECTORIES)
#will only include B.h but not A.h. compilation will fail.
target_include_directories(outputModuleA /inc ${libBInc})
I did not find any solution in Cmake itself to solve this problem. It's confusing me since all the include-directories must be known when the libraries are passed transitive, which is stated in the documentation. But I understand that getting the target include directories of just the passed lib does not include the other ones.
Since target_link_libraries does also not work this way I can only think of a maybe recursive solution? But for that my knowledge is just non-existent.
target_link_libraries with something like HEADERS_ONLY would be helpfull for this job.
Also one can say: if the output module contains all the definitions it won't be a problem, since the linker then knows them and will do its magic.
But this is also unwanted, since we use the generated static-libraries to place them into sections in different regions of the RAM directly. This would then mean to create another linker-script for partial linking which defines sections which then can be again moved. But the more we go this direction, the less we need CMake for it.
Instead of get_target_property use $<TARGET_PROPERTY> generator expression: the property's value, extracted by that expression, already includes transitive propagation:
target_include_directories(outputModuleA PRIVATE
$<TARGET_PROPERTY:libB,INTERFACE_INCLUDE_DIRECTORIES>
)
Note, that generator expressions has limited usage: not all functions expects them. Documentation for target_include_directories clearly states that the command supports generator expressions.
I'm using cmake-3.16, and for other technical reason, I must use MODULE to make a shared lib(*.so) in Linux instead of using SHARED.
But with MODULE, cmake does NOT produce target file with name like "libDummy.so.x.x.x", and automatically create a symbolic link with name like "libDummy.so".
So I manually use OUTPUT_NAME_RELEASE to declare the target name as following:
add_library( Dummy MODULE Dummy.cpp )
set_target_properties( Dummy PROPERTIES
PREFIX ""
SUFFIX ""
OUTPUT_NAME_RELEASE "Dummy.so.${PROJECT_VERSION}"
OUTPUT_NAME_DEBUG "Dummy.so.${PROJECT_VERSION}"
)
install( TARGETS Dummy LIBRARY DESTINATION somewhere )
But I don't know how to add a symbolic link for it.
I found the cmake command:
file( CREATE_LINK "Origin.so.0.1.2" "Symlnk.so" RESULT act_res SYMBOLIC )
looks like doing my requirement.
But I don't Known its syntax. I searched in cmake documents, there are very less comments about it.
How to refer the target name of the original Module in the command file( CREATE_LINK ),
and how to make the symbolic link with relative path,
and how to store the symblink into the same folder of the module?
Thx!
I'm not familar with cmake but in CMakeLists.txt we set the target shared library name like this.
add_library( mylib SHARED ${source_list} )
This generates libmylib.so and other settings in CMakeLists.txt are defined for mylib like
about the mylib
and also we can use shell environment variable to do some selective settings like
target_compile_definitions( mylib PRIVATE -DQQQ -D... )
Also it is possible to use shell environment variable to do some selective things.
if(defined env{MYVAR})
set(CMAKE_C_FLAGS "-g -DXYZ")
else()
set(CMAKE_C_FLAGS "-DXYZ")
endif()
I would be happy if I could set the target shared library name as a variable according to the environment variable and use that selected name variable as the shared library name in all other settings. In other words, is it possible to do things like below?
if (defined ENV{FOR_QEMU})
set_name(target_name "simlib_qemu")
else ()
set_name(target_name "simlib")
endif ()
add_library(target_name SHARED ${source_list} )
target_compile_definitions( target_name PRIVATE -DQQQ -D... )
...
You can set the output name of a target to anything you like via:
set_target_properties(target_name PROPERTIES OUTPUT_NAME "whatever")
Then instead of libtarget_name.so, you'll get libwhatever.so. You would continue to refer to the target as target_name in your CMakeLists.txt.
However, since this will only work during configure time anyway, I strongly urge you to use a normal CMake variable instead. You may initialize it from the environment if it is not set, like so:
option(FOR_QEMU "Enable if building with Qemu support" "$ENV{FOR_QEMU}")
add_library(simlib SHARED ${source_list})
target_compile_definitions(simlib PRIVATE -DQQQ -D...)
if (FOR_QEMU)
set_target_properties(target_name PROPERTIES OUTPUT_NAME "simlib_qemu")
endif ()
This way, the CMake variable FOR_QEMU is the de-facto control and it is initialized on the first execution if the matching env-var is set. It will also appear with documentation in the cache, so other developers may query the build system directly for all its configuration points. Bear in mind: CMake is not Make and reading from the environment on every configure is a surprising behavior and generally bad practice.
I have multiple targets that are being made in a CMake project. Each target has a different linkscript (LD file). How do I write the CMakeLists.txt file to make this happen? This is for an embedded project with C/C++/ASM files.
This is what I have so far. The problem is that LINKER_SCRIPT is defined globally and not per-target.
# add alpha target
add_executable(alpha.elf ${SOURCES})
target_compile_definitions(alpha.elf PUBLIC -DALPHA_DEFINED)
set(LINKER_SCRIPT ${CMAKE_SOURCE_DIR}/Linker/alpha.ld)
# add beta target
add_executable(beta.elf ${SOURCES})
target_compile_definitions(beta.elf PUBLIC -DBETA_DEFINED)
set(LINKER_SCRIPT ${CMAKE_SOURCE_DIR}/Linker/beta.ld)
set(CMAKE_EXE_LINKER_FLAGS
"${CMAKE_EXE_LINKER_FLAGS} -T ${LINKER_SCRIPT}")
The problem is that LINKER_SCRIPT gets overwritten and the last definition is the one used. How can I make this work?
I have tried to define per-target variable using the following, however the output is not as expected. The file gets compiled, however things are not where they should be. For example, the generated HEX file does not start at 0x08000000 which is where it should be defined per the LD file.
set_target_properties(alpha.elf PROPERTIES
CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-Map=${PROJECT_BINARY_DIR}/alpha.elf.map -T ${CMAKE_SOURCE_DIR}/Linker/alpha.ld")
The variable LINKER_SCRIPT is just being over-ridden the second time you set it to a value. It doesn't have global scope but sub-directory / function scope. But like any variable it takes on its latest value.
CMAKE_EXE_LINKER_FLAGS is being used for both targets in this case. Splitting this into separate sub-directories may work but I've never tried it.
There are no per-target variables that I am aware of. set_target_properties is used to set properties. Some properties are known to CMake, but the property CMAKE_EXE_LINKER_FLAGS is not one of them. It should just be ignored when generating the build files.
Try using target_link_options to set per-target property LINK_OPTIONS which is known and the option will show up when linking the executable.
For example target_link_options(alpha.elf PRIVATE -T${CMAKE_SOURCE_DIR}/Linker/alpha.ld). I haven't used it with options that have a space in them so that might be a problem.
To re-link if the linker script changes then refer to this answer:
https://stackoverflow.com/a/42138375/1028434
I am using CMake to build a simple C++ project, hereafter named P. The structure of P is quite simple:
P/src/
P/src/package1
P/src/packege2
P/src/...
P/src/main-app
I would like to collect the libraries in package1, package2, ... in a variable called P_LIBS.
In a first attempt, I tried to collect the libraries available in package1, package2, ... in the variable called P_LIBS initially set in the src/CMakeLists.txt file. However, the updates to P_LIBS made in the CMakeLists.txt of the subfolders are not propagated to the parent folder.
I would rather not write a list of libraries in the main CMakeLists.txt file. I would rather modify such variable while moving in the directory tree.
After a search on the internet I could not find any valid suggestion. If I look at the various Find files, I only see long listings of libraries in their main CMakeLists.txt file.
Is there a way to do what (I hope) I explained above?
Thanks to sakra's link I was able to 'propagate' names up to the parent folder. However, the names I add to the P_LIBS variable are later interpreted as 'library' names, not as reference to CMake targets. In other words, if
P_LIBS = {a, b}
the 'a' and 'b' are interpreted as the library names, i.e. CMake generates:
gcc [...] -l a -o exe
instead of
gcc [...] /path/to/a.o -o exe
(.o or other extensions)
You are propably constructing the targets list as a string, try to make them a list instead. For example:
# in package1/CMakeLists.txt
set(P_LIBS ${P_LIBS} a b PARENT_SCOPE)