Provides the parameters required to issue a kernel-mode fast-write call.
#include <sys/device.h> #include <sys/comio.h>
int ddioctl (devno, op, parmptr, devflag, chan, ext) dev_t devno; int op; struct status_block *parmptr; ulong devflag; int chan, ext;
The CIO_GET_FASTWRT operation returns the parameters required to issue a kernel-mode fast write for a particular device. Only a kernel-mode process can issue this entry point and use the fast-write function. The parameters returned are located in the cio_get_fastwrt structure in the /usr/include/sys/comio.h file.
Note: This operation should not be called by user-mode processes.
devno | Specifies major and minor device numbers. |
op | Indicates the entry point for the CIO_GET_FASTWRT operation. |
parmptr | Points to a cio_get_fastwrt structure. This structure is defined in the /usr/include/sys/comio.h file. |
devflag | Indicates the DKERNEL flag. This flag must be set, indicating a call by a kernel-mode process. |
chan | Specifies the channel number assigned by the device-handler ddmpx entry point. |
ext | Specifies the extended subroutine parameter. This parameter is device-dependent. |
A CIO_GET_FASTWRT operation can be called from the process environment only.
In general, communication device handlers use the common codes defined for an operation. However, device handlers for specific communication devices may return device-specific codes. The common return codes for the CIO_GET_FASTWRT operation are:
The ddioctl device driver entry point in AIX Version 4.3 Technical Reference: Kernel and Subsystems Volume 1.
The ddwrite entry point, dd_fastwrt entry point.