> > Given that libxl always passes -nodefaults to QEMU, this patch is going > > to effectively disable xen_platform_pci for all Xen users. It is not a > > good idea. With the patch applied a Xen user would have no way to enable > > xen_platform_pci except for passing some magic command line runes via > > device_model_args_hvm. > > In fact this code only runs for "-M xenfv". If you use "-M pc", the > xen-platform device has to be added manually. Perhaps it would be > worthwhile to do the opposite, i.e. add the xen-platform device to "-M > pc" if not using -nodefaults.
/me looks at the code. Yes, all the differences between xenfv and pc machine types are guarded by if (xen_enabled()) these days, except for adding the platform device. So using the pc machine type should just work on xen, and give you a machine without the platform device. So it can be added via -device, at any slot, if needed. No need to patch qemu at all. Adding or not adding xen-platform can easily handled by libxl then, depending on the xen_platform_pci switch in the config file. cheers, Gerd
