---
title: inputSyncCallback
framework: kernel
role: pseudoSymbol
path: kernel/iostream/1809761-inputsynccallback
---

# inputSyncCallback

Input callback function to be implemented by a subclass.

## Declaration

```occ
virtual void inputSyncCallback(
 UInt32token ); 
```

## Parameters

- `token`: A 32-bit token value that can be used by convention to communicate from user space to the stream. The semantics of this value are defined by the IOStream subclass.

## Overview

Overview The inputSyncCallback() method is called as a result of a fast trap from user space. It is called on the same thread as the user request, so no context switch is necessary.

## See Also

### Managing notifications

- [inputCallback](kernel/iostream/1809754-inputcallback.md)