PPC_KERNEL_SEG0
#define PPC_KERNEL_SEGMENT (PPC_KERNEL_SEG0 + PPC_KERNEL_SR)
pmap_kernel()->pm_sr[i] = (PPC_KERNEL_SEG0 + i) | SR_NOEXEC;
ppc_mtsrin(PPC_KERNEL_SEG0 + i, i << ADDR_SR_SHIFT);