rdr2
pcb->pcb_dbregs->dr[2] = rdr2();
if (rdr2() < (vaddr_t)VM_MAXUSER_ADDRESS)
initdbstate.dr[2] = rdr2();
cpudata->drs[NVMM_X64_DR_DR2] = rdr2();
cpudata->drs[NVMM_X64_DR_DR2] = rdr2();