From: David Howells <dhowells@xxxxxxxxxx> Date: Thu, 15 Apr 2010 00:52:14 +0100 > David VomLehn <dvomlehn@xxxxxxxxx> wrote: > >> > Can the use of va_start() clobber lots of registers, thereby rendering the >> > exercise pointless on some arches? >> > >> >> The implementations I'm familiar with only need one or two registers. What >> it *does* do is to force the contents of registers being used to pass >> argument values onto the stack. This is roughly what gcc does for asm() >> statements when you tell it registers are clobbered. > > How about something like Sparc, where you can pass up to 8 arguments (if I > remember correctly) in registers. I'm not sure how Sparc handles varargs > functions, though. 6 arguments, and all arguments get popped onto the stack into the argument save area when doing varargs so you can access them as an array. Stack looks like: struct register_window window; unsigned long args[...]; -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html