MMCR0_EBE
val &= ~(MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC | MMCR0_PMAO |
if (!(mmcr0 & MMCR0_EBE))
mmcr0 |= MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC_U6;