rdr3
pcb->pcb_dbregs->dr[3] = rdr3();
if (rdr3() < (vaddr_t)VM_MAXUSER_ADDRESS)
initdbstate.dr[3] = rdr3();
cpudata->drs[NVMM_X64_DR_DR3] = rdr3();
cpudata->drs[NVMM_X64_DR_DR3] = rdr3();