SR_NOEXEC
pm->pm_sr[k] = (seg + k) | SR_NOEXEC;
pmap_kernel()->pm_sr[i] = (PPC_KERNEL_SEG0 + i) | SR_NOEXEC;
pmap_kernel()->pm_sr[0] &= ~SR_NOEXEC;
if (pm->pm_sr[sn] & SR_NOEXEC)
pm->pm_sr[sn] &= ~SR_NOEXEC;
pm->pm_sr[sn] |= SR_NOEXEC;
if (pm->pm_sr[sn] & SR_NOEXEC)
pm->pm_sr[sn] &= ~SR_NOEXEC;