---
title: ioRead8
framework: kernel
role: pseudoSymbol
path: kernel/iopcidevice/1811039-ioread8
---

# ioRead8

Reads a 8-bit value from an I/O space aperture.

## Declaration

```occ
virtual UInt8 ioRead8(
 UInt16 offset,
 IOMemoryMap *map = 0 ); 
```

## Parameters

- `offset`: An offset into a bus or device's I/O space aperture.
- `map`: If the offset is relative to the beginning of a device's aperture, an IOMemoryMap object for that object should be passed in. Otherwise, passing zero will write the value relative to the beginning of the bus' I/O space.

## Return Value

Return Value The value read.

## Overview

Overview This method will read a 8-bit value from an offset in an I/O space aperture. If a map object is passed in, the value is read relative to it, otherwise to the value is read relative to the I/O space aperture for the bus. This function encapsulates the differences between architectures in generating I/O space operations. An eieio instruction is included on PPC.

## See Also

### Miscellaneous

- [configRead16](kernel/iopcidevice/1810221-configread16.md)
- [configRead32](kernel/iopcidevice/1810249-configread32.md)
- [configRead8](kernel/iopcidevice/1810282-configread8.md)
- [configWrite16](kernel/iopcidevice/1810325-configwrite16.md)
- [configWrite32](kernel/iopcidevice/1810356-configwrite32.md)
- [configWrite8](kernel/iopcidevice/1810381-configwrite8.md)
- [enablePCIPowerManagement](kernel/iopcidevice/1810420-enablepcipowermanagement.md)
- [extendedConfigRead16](kernel/iopcidevice/1810448-extendedconfigread16.md)
- [extendedConfigRead32](kernel/iopcidevice/1810495-extendedconfigread32.md)
- [extendedConfigRead8](kernel/iopcidevice/1810539-extendedconfigread8.md)
- [extendedConfigWrite16](kernel/iopcidevice/1810577-extendedconfigwrite16.md)
- [extendedConfigWrite32](kernel/iopcidevice/1810617-extendedconfigwrite32.md)
- [extendedConfigWrite8](kernel/iopcidevice/1810659-extendedconfigwrite8.md)
- [extendedFindPCICapability](kernel/iopcidevice/1810707-extendedfindpcicapability.md)
- [findPCICapability](kernel/iopcidevice/1810749-findpcicapability.md)
- [getBusNumber](kernel/iopcidevice/1810790-getbusnumber.md)
- [getDeviceMemoryWithRegister](kernel/iopcidevice/1810831-getdevicememorywithregister.md)
- [getDeviceNumber](kernel/iopcidevice/1810861-getdevicenumber.md)
- [getFunctionNumber](kernel/iopcidevice/1810892-getfunctionnumber.md)
- [hasPCIPowerManagement](kernel/iopcidevice/1810931-haspcipowermanagement.md)
- [ioDeviceMemory](kernel/iopcidevice/1810959-iodevicememory.md)
- [ioRead16](kernel/iopcidevice/1810986-ioread16.md)
- [ioRead32](kernel/iopcidevice/1811005-ioread32.md)
- [ioWrite16](kernel/iopcidevice/1811083-iowrite16.md)
- [ioWrite32](kernel/iopcidevice/1811113-iowrite32.md)
- [ioWrite8](kernel/iopcidevice/1811151-iowrite8.md)
- [mapDeviceMemoryWithRegister](kernel/iopcidevice/1811470-mapdevicememorywithregister.md)
- [setBusMasterEnable](kernel/iopcidevice/1811490-setbusmasterenable.md)
- [setConfigBits](kernel/iopcidevice/1811511-setconfigbits.md)
- [setIOEnable](kernel/iopcidevice/1811528-setioenable.md)
- [setMemoryEnable](kernel/iopcidevice/1811543-setmemoryenable.md)