Constantine Kousoulos <wuwei@xxxxxxxxxxx> writes: > I have a printf() function written in C using va_start, va_arg, > etc. It works fine on i386. Lately, i needed it on my amd64 > machine. However, although it builds, it does not work. > > After reading the x86_64 ABI, i found out that on amd64 each > function's args are moved to specific registers and not to the stack > (like on i386). > > Do i need to do something extra to use varargs functions on x86_64? No. Doing a #include of <stdarg.h> should suffice. Note that on x86_64, unlike i386, int and long have different sizes. That means that varargs functions have more chances to make mistakes. If the caller passes a long, you must use va_arg(long), not va_arg(int). Ian
