glauxosdever wrote:
Do you think there is much point restricting your support to P2 machines and rejecting everything that is newer than that?
Why would getting an old PC to test on prevent you from supporting newer hardware? I've used an old P4 system for real hardware testing of my OS, one thing that makes it more useful than a newer system is the presence of a serial port, allowing me to see debugging output. I have done basic testing (i.e. booting the OS from CD) on more modern hardware, but I certainly don't have the funds to dedicate expensive hardware to OS testing.
Also, it's a good idea to test on every available emulator/virtualiser before testing on real hardware. They each have their own "quirks" and bugs, just like real systems. I do most of my development with QEMU, but I tested on Bochs, VirtualBox and VMWare before real hardware. The kind of differences you see between emulators are similar to the kinds of differences you see between real systems.
If something as fundamental as IRQs aren't working, you're doing something wrong and it's highly likely you'll be able to replicate the issue on a different emulator/virtualiser.