86Box/src/cpu/x86_ops_msr.h

static int
opRDTSC(uint32_t fetchdat)
{
    if (!cpu_has_feature(CPU_FEATURE_RDTSC)) {
        cpu_state.pc = cpu_state.oldpc;
        x86illegal();
        return 1;
    }
    if ((cr4 & CR4_TSD) && CPL) {
        x86gpf("RDTSC when TSD set and CPL != 0", 0);
        return 1;
    }
    EAX = tsc & 0xffffffff;
    EDX = tsc >> 32;
    CLOCK_CYCLES(1);
#ifdef USE_DYNAREC
    if (cpu_use_dynarec)
        update_tsc();
#endif
    return 0;
}

static int
opRDPMC(uint32_t fetchdat)
{
    if (ECX > 1 || (!(cr4 & CR4_PCE) && (cr0 & 1) && CPL)) {
        x86gpf("RDPMC not allowed", 0);
        return 1;
    }
    EAX = EDX = 0;
    CLOCK_CYCLES(1);
    return 0;
}