The types of floating-point linkage are:

Software floating-point linkage means that the parameters and return value for a function are passed using the ARM integer registers r0 to r3 and the stack.

Hardware floating-point linkage uses the Vector Floating-Point (VFP) coprocessor registers to pass the arguments and return value.

The benefit of using software floating-point linkage is that the resulting code can be run on a core with or without a VFP coprocessor. It is not dependent on the presence of a VFP hardware coprocessor, and it can be used with or without a VFP coprocessor present.

The benefit of using hardware floating-point linkage is that it is more efficient than software floating-point linkage, but you must have a VFP coprocessor.