Technical Reference: Kernel and Subsystems, Volume 1

d_mask Kernel Service

Purpose

Disables a direct memory access (DMA) channel.

Syntax

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/dma.h>

void d_mask ( channel_id) int channel_id;

Parameter

channel_id

Specifies the DMA channel. This parameter is returned by the d_init service.

Description

The d_mask kernel service disables the DMA channel specified by the channel_id parameter.

The d_mask kernel service is typically called by a device driver deallocating the resources associated with its device. Some devices require it to be used during normal device operation to control DMA requests and avoid spurious DMA operations.

Note

The d_mask service, like all DMA services, should not be called unless the d_init service has allocated the DMA channel.

Note

The d_mask kernel service is not supported on the 64-bit kernel.

Execution Environment

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

Return Values

The d_mask service has no return values.

Related Information

The d_init kernel service, d_unmask kernel service.

I/O Kernel Services and Understanding Direct Memory Access (DMA) Transfers in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.