MIPS_SR_UX
tf->tf_regs[_R_SR] |= MIPS_SR_UX;
pcb->pcb_context.val[_L_SR] |= MIPS_SR_KX | MIPS_SR_UX;
l->l_md.md_utf->tf_regs[_R_SR] = MIPS_SR_KX | MIPS_SR_UX;