Having trouble compiling 32-bit binary on 64-bit linux armv8 machine - c++

Question

I am trying to use a c++ ARM 32-bit library on a Jetson Tx2, which is an ARM 64-bit linux machine. When I try to compile some of the sample code provided with the library I get the following compilation error:
/usr/bin/ld: skipping incompatible /home/nvidia/libroyale/bin/libroyale.so
when searching for -lroyale
/usr/bin/ld: cannot find -lroyale
collect2: error: ld returned 1 exit status
CMakeFiles/sampleCameraInfo.dir/build.make:94: recipe for target
'sampleCameraInfo' failed
make[2]: *** [sampleCameraInfo] Error 1
CMakeFiles/Makefile2:67: recipe for target
'CMakeFiles/sampleCameraInfo.dir/all' failed
make[1]: *** [CMakeFiles/sampleCameraInfo.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2
I assume that this error is because the 32-bit library is somehow incompatible with a 64-bit machine.
I have been browsing other StackOverflow forums on similar issues, and in accordance with those forum recommendations added the -m32 flag to CXXFLAGS and LDFLAGS when I compile. However, I then get the following error:
g++: error: unrecognized command line option ‘-m32’
CMakeFiles/sampleCameraInfo.dir/build.make:62: recipe for target
'CMakeFiles/sampleCameraInfo.dir/sampleCameraInfo.cpp.o' failed
make[2]: *** [CMakeFiles/sampleCameraInfo.dir/sampleCameraInfo.cpp.o] Error 1
CMakeFiles/Makefile2:67: recipe for target
'CMakeFiles/sampleCameraInfo.dir/all' failed
make[1]: *** [CMakeFiles/sampleCameraInfo.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2
Some other StackOverflow threads said that in order to use the -m32 flag, one has to run the command:
sudo apt-get install g++-multilib
I don't think that the installation is working correctly, as I'm getting the following errors:
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
g++-multilib:armhf : Depends: cpp:armhf (>= 4:5.3.1-1ubuntu1) but it is
not going to be installed
Depends: gcc-multilib:armhf (>= 4:5.3.1-1ubuntu1) but it is not going to be installed
Depends: g++:armhf (>= 4:5.3.1-1ubuntu1) but it is not going to be installed
Depends: g++-5-multilib:armhf (>= 5.3.1-3~) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
Any suggestions would be very much appreciated. Thanks!
UPDATE: I realized that the -m32 flag is only supported on x86 linux machines. Does anyone know if there is some equivalent for ARM machines?

Answer 1

I had a look at the GCC documentation, especially on the following pages:
https://gcc.gnu.org/onlinedocs/gcc-7.1.0/gcc/x86-Options.html
https://gcc.gnu.org/onlinedocs/gcc-7.1.0/gcc/AArch64-Options.html
Looks like for the GNU compilers x86 is one type of CPU; you can create 16-, 32- or 64-bit code for this CPU type.
However it also looks like for the GNU compilers 32-bit ARM CPUs and 64-bit ARM CPUs are two completely different CPU types.
Therefore compiling for 32-bit ARM with a 64-bit ARM compiler is the same as compiling for x86 with an ARM compiler: It won't work.
Of course the 32-bit library will not be accepted; an ARM compiler would not accept a x86 library, either.