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AIX Version 4.3 Kernel and Subsystems Technical Reference, Volume 1

io_att Kernel Service


Selects, allocates, and maps a region in the current address space for I/O access.


#include <sys/types.h>
#include <sys/errno.h>
#include <sys/vmuser.h>
#include <sys/adspace.h>
caddr_t io_att (iohandle, offset)
vmhandle_t iohandle;
caddr_t offset;


iohandle Specifies a handle for the I/O object to be mapped in the current address space.
offset Specifies the address offset in both the I/O space and the virtual memory region to be mapped.


Attention: The io_att service will crash the kernel if there are no more free regions.

The io_att kernel service performs these four tasks:

The io_att kernel service assumes an address space model of fixed-size I/O objects and virtual memory address space regions.

Execution Environment

The io_att kernel service can be called from either the process or interrupt environment.

Return Values

The io_att kernel service returns an address for the offset in the virtual memory address space.

Implementation Specifics

The io_att kernel service is part of Base Operating System (BOS) Runtime.

Related Information

The io_det kernel service.

Memory Kernel Services and Understanding Virtual Memory Manager Interfaces in AIX Kernel Extensions and Device Support Programming Concepts.

Virtual Memory Manager Overview.

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