Back in the day you used to be able to set DEBUG_IOPORT in ioport.c and get qemu to dump what (x86) I/O ports were being accessed by the guest. This was rather useful for finding out what closed source device drivers were up to.
Now you're supposed to use cpu_in/cpu_out tracepoints instead. However for the majority of guests these tracepoints will never be called. So this patch tries to rationalize all of that. It: - replaces cpu_in/cpu_out with ioport_in/ioport_out tracepoints - moves them down in the stack, so they actually get called - fixes various details like address size It turns out this is still not particularly useful for debugging because (a) it creates massive amounts of log messages and (b) there's no way to select a range of addresses or a device of interest. For example, if you have a serial port, everything else gets swamped by I/O access to the serial port. Maybe using a different tracing backend (eg. stap) would help? Anyway, it still seems to me to be an improvement over the current situation. Rich.
