A system and method for injecting hardware errors into a microprocessor system is described. In one embodiment, a software interface between system software and system firmware is established. Software test and debug for software error handlers may thus be supported. The software interface may support both a query mode call and a seed mode call. When a query mode call is issued, it may request whether or not the system firmware and hardware support the injection of a specified kind of error. A return from this call may be used to make a list of supported errors for injection. When a seed mode call is issued, the corresponding error may be injected into the hardware.