---
title: mbuf_datastart
framework: Kernel
role: symbol
role_heading: Function
platforms: [macOS 10.4+]
path: kernel/1535666-mbuf_datastart
---

# mbuf_datastart

## Declaration

```occ
void * mbuf_datastart(mbuf_t mbuf);
```

## Parameters

- `mbuf`: The mbuf.

## Return Value

Return Value A pointer to smallest possible value for data.

## Discussion

Discussion Returns the start of the space set aside for storing data in an mbuf. An mbuf's data may come from a cluster or be embedded in the mbuf structure itself. The data pointer retrieved by mbuf_data may not be at the start of the data (mbuf_leadingspace will be non-zero). This function will return a pointer that matches mbuf_data() - mbuf_leadingspace().