---
title: "init(header:addr:size:value:trailer:)"
framework: Hypervisor
role: symbol
role_heading: Initializer
path: "hypervisor/hv_ion_message_t/init(header:addr:size:value:trailer:)"
---

# init(header:addr:size:value:trailer:)

Creates a new I/O notifier message with the parameters you provide.

## Declaration

```swift
init(header: mach_msg_header_t, addr: UInt64, size: UInt64, value: UInt64, trailer: mach_msg_trailer_t)
```

## Parameters

- `header`: The Mach message header.
- `addr`: The address of the I/O write.
- `size`: The size of the value written.
- `value`: The value written to addr.
- `trailer`: The Mach message trailer.

## See Also

### Initializers

- [init()](hypervisor/hv_ion_message_t/init().md)