---
title: mandatoryFeatures
framework: virtualization
role: symbol
role_heading: Instance Property
path: virtualization/vzcustomvirtiodeviceconfiguration/mandatoryfeatures
---

# mandatoryFeatures

The set of mandatory features that the device offers and the guest must accept.

## Declaration

```swift
var mandatoryFeatures: VZVirtioFeatureSet { get }
```

## Discussion

Discussion The mandatory features are the set of features that the device offers and the guest must accept. The framework won’t successfully initialize the device if the guest driver fails to accept this set of features. The feature bit VIRTIO_F_VERSION_1 is always set to 1 internally by default.