IOMMU_MAP_ENTRY_FAKE
KASSERT(((a->flags | b->flags) & IOMMU_MAP_ENTRY_FAKE) != 0 ||
entry->flags |= IOMMU_MAP_ENTRY_FAKE;
entry->flags &= ~IOMMU_MAP_ENTRY_FAKE;
fentry.flags = IOMMU_MAP_ENTRY_FAKE;