• In general, gcc-ia16's handling of far pointers is considered experimental. (In a wswan target context, this means all accesses outside of the console's internal RAM.) Caveat emptor.

In some cases, when calling pointers from arrays of far function pointers in optimization modes >= -O1, the code will be miscompiled. This is a known issue, with no ETA for a fix.

One can work around this by annotating the affected function to be compiled without optimizations. In particular, one can create a separate function that only acts as a wrapper for the function call:

__attribute__((noinline, optimize("-O0"))) // https://github.com/tkchia/gcc-ia16/issues/120
void call_to_my_function_table(uint8_t index) {
    my_function_table[index]();
}

The wwitch target does not support relocation; as such, far functions (which interrupt handlers have to be) cannot be created in sections other than the default text section. This can be most easily achieved by building with -fno-function-sections in CFLAGS.