You are probably using gcc which complains about
__cdecl
which is compiler and processor specific. If your embedded system does not use a x86 CPU you may use an empty global definition to hide it:
#define __cdecl
However, there may be other issues coming up so you should check if you can setup your development environment for your target platform.
With x86 CPUs, gcc uses
__attribute__
to specify the C calling convention and you can use:
#define __cdecl __attribute__((__cdecl__))
For further questions you should provide additional information about the used compiler (name and version) and target platform (architecture and OS).