ioctl Processing

User space applications can send an ioctl command after obtaining a valid file descriptor and attaching itself to a specific PPA with which it needs to communicate. To send an ioctl command, you can use the I_STR ioctl.

You can create the I_STR ioctl by passing the following to the ioctl()(2) system call:

The strioctl structure contains the following members:

struct strioctl {
int ic_cmd;
int ic_timout;
int ic_len;
char *ic_dp;
};

The description of the members of the strioctl structure is as follows:

ic_cmd

ic_timout

ic_len

ic_dp

The I_STR ioctl causes the stream head to create an M_IOCTL message that includes the associated information (passed in ic_dp) required by DLPI or the device driver to process the command (passed in ic_cmd). The associated information is passed as the second message block following the M_IOCTL message block.

All the ioctl commands with an I_STR request are passed to the driver instance and DLPI through the ioc_cmd field (present in iocblk structure).

The STREAMS kernel modules that reside on top of DLPI (transport layer) can generate ioctl by constructing an M_IOCTL message block that contains the iocblk structure.

	NOTE: The ioc_cmd field of the iocblk structure is set to appropriate command supported by device driver or DLPI. The b_cont of the M_IOCTL message block can point to the associated information required by the driver or DLPI.

For more information, see STREAMS/UX for the HP 9000 Reference Manual.