How to generate a shared library (SO/DLL) using CMake-based toolchain in Simulink

Hello everyone,

I have defined a CMake-based toolchain in MATLAB 2024b as follows:

% matlab script 
tc = target.create('Toolchain', 'Name', 'MySimpleToolchain');

tc.Builder = target.create('CMakeBuilder');
tc.Builder.Generator = 'Ninja';
tc.Builder.ToolchainFile = fullfile(pwd, '\LinuxRT_Toolchain\LinuxRT.cmake');


tc.Builder.SupportedBuildTypes(end+1) = ...
   target.create('CMakeBuildType', ...
   'Name', 'FastMath', ...
   'GeneratesDebugSymbols', false, ...
   'DebugBuildType', 'FastMathWithDebug');
tc.Builder.SupportedBuildTypes(end+1) = ...
   target.create('CMakeBuildType', ...
   'Name', 'FastMathWithDebug', ...
   'GeneratesDebugSymbols', true);

tc.EnvironmentConfiguration(1).HostOperatingSystemSupport.Linux = true;
tc.EnvironmentConfiguration(1).HostOperatingSystemSupport.Windows = false;
tc.EnvironmentConfiguration(1).HostOperatingSystemSupport.Mac = false;
tc.EnvironmentConfiguration(1).SystemPaths = ...
  {'$(MW_MINGW64_LOC)/bin', 'C:/Ninja'};

tc.EnvironmentConfiguration(2) = target.create('EnvironmentConfiguration');
tc.EnvironmentConfiguration(2).HostOperatingSystemSupport.Linux = false;
tc.EnvironmentConfiguration(2).HostOperatingSystemSupport.Windows = true;
tc.EnvironmentConfiguration(2).HostOperatingSystemSupport.Mac = false;
tc.EnvironmentConfiguration(2).SystemPaths = ...
  {'C:/Ninja'};

windowsProc = target.get('Processor', 'Intel-x86-64 (Windows64)');
tc.SupportedHardware(end+1) = ...
  target.create('HardwareComponentSupport', 'Component', windowsProc);

linuxProc = target.get('Processor', 'Intel-x86-64 (Linux 64)');
tc.SupportedHardware(end+1) = ...
  target.create('HardwareComponentSupport', 'Component', linuxProc);

macProc = target.get('Processor', 'Intel-x86-64 (Mac OS X)');
tc.SupportedHardware(end+1) = ...
  target.create('HardwareComponentSupport', 'Component', macProc);

target.add(tc);

I use this toolchain with grt.tlc to generate an executable from a Simulink model — this works smoothly.

Now, I would like to generate a shared library (.so or .dll, depending on the platform) from the model instead of an executable. But the defined CMakelists.txt file has the following statements:

...
# Definition of target "samplemodel"
add_executable(samplemodel  ${MATLAB_ROOT}/rtw/c/src/common/rt_main.c)
...

My questions are:

1. Should I simply add certain build options to the existing toolchain to change add_executable(...) statement with add_library(....)?
2. Or is it necessary to create a custom TLC file instead of using grt.tlc?

Thanks in advance for your help.

Answer 1

[Aabha]

Hi @Anil Ozturk,

I understand that you wish to generate a shared library from your model code instead of an executable. In this case, adding certain specific build options to the existing toolchain may not be useful, since MATLAB does not change the structure of the generated ‘CMakeLists’ file based on the additional build options alone. The documentation on configuring the ‘CMake’ build process clarifies what build types and customization options are available when using ‘CMake’, as follows:

https://www.mathworks.com/help/releases/r2024b/coder/ug/configure-cmake-build-process.html

The code generation process produces 'CMakeLists.txt', which drives the build. However, changing the output type (executable vs. library) is controlled in Simulink via the system target file and build settings, not via 'CMake' flags alone.

As an alternative, you can modify the generated ‘CMakeLists’ file to include the ‘add_library’ option, by using a flag ‘BUILD_SHARED_LIB’ as follows:

if(BUILD_SHARED_LIB) 
    add_library(modelname SHARED ${MODEL_SOURCES}) 
else() 
    add_executable(modelname ${MODEL_SOURCES} ${RT_MAIN}) 
end

Then, you can pass the flag using the additional build options as follows:

tc.Builder.AdditionalBuildOptions = {'-DBUILD_SHARED_LIB=ON'}; 

After this, when you build, MATLAB will generate the normal ‘CMakeLists.txt’, but also include the additional flag in the ‘cmake’ command line.

Alternatively, you can build a shared library by configuring the code generator to use the system target file ‘ert_shrlib.tlc’. This method does not require any modifications in the existing toolchain and will generate a shared library version of your model code. Also, it does not change the code that the code generator produces for your model. Please refer to the following documentation link for more information regarding the same:

https://www.mathworks.com/help/releases/r2024b/ecoder/ug/creating-and-using-host-based-shared-libraries.html

I hope this helps.

[Anil Ozturk]

Hi Aabha,

Thanks for your reply. You mentioned that I can modify the generated ‘CMakeLists’ file to include the ‘add_library’ option, by using a flag ‘BUILD_SHARED_LIB’. Could you please elaborate how I can do it? Where should I place the if statement you suggested? Since Simulink generates CMakeLists.txt and puts add_executable line during the auto code generation process, I don't know exactly where to place the suggested lines.

On the other hand, I agree that ert_shrlib.tlc is a better solution for my case. Hoewever, I don't have Embedded Coder license and that's why, I'm trying to find a solution based on grt.tlc.

Regards

Anil

Answer 2

[Chris Cripps]

Hi @Anil Ozturk.

You can use the slbuild command line API to specify a BuildOutputType for the proceeding build process. For example

slbuild("samplemodel", "BuildOutputType", "SharedLibrary")

will build a shared library for the model 'samplemodel'.

Valid values for BuildOutputType are Auto, Executable, StaticLibrary and SharedLibrary.

Please see the slbuild reference page for more information.