AMDIOMMU_EV_SZ
unit->event_log = kmem_alloc_contig(AMDIOMMU_EV_SZ *
kmem_free(unit->event_log, unit->event_log_size * AMDIOMMU_EV_SZ);
_Static_assert((1 << AMDIOMMU_EV_SZ_SHIFT) == AMDIOMMU_EV_SZ,