if (cpuFamily == CPUID_FAMILY_686) {
	if (cpuModel == CPUID_MODEL_CORE || cpuModel == CPUID_MODEL_CORE2) {
	uint64_t	prfsts;
	
	prfsts = rdmsr64(IA32_PERF_STS);
	tscGranularity = (uint32_t)(prfsts >> BusRatioShift) & BusRatioMask;
	} else {
	    panic("rtclock_init: unknown CPU model: 0x%X\n",
	      cpuModel);
	}
    } else {
	panic("rtclock_init: unknown CPU family: 0x%X\n",
	      cpuFamily);
    }