Issues a control command to an open device.
#include <sys/types.h>
#include <sys/errno.h>
#include <fcntl.h>
int fp_ioctlx (fp, cmd, arg, ext, flags, retval)
struct file *fp;
unsigned long cmd;
caddr_t arg;
ext_t ext;
unsigned long flags;
long *retval;The fp_ioctlx kernel service is an internal interface to the function provided by the ioctl subroutine.
The fp_ioctlx kernel service issues a control command to an open device. Some drivers need the return value that is returned by the kernel service if there is no error. This value is not available through the fp_ioctl kernel service. The fp_ioctlx kernel service allows this data to be passed.
| Item | Description |
|---|---|
| fp | Points to a file structure returned by the fp_open or fp_opendev kernel service. |
| cmd | Specifies the specific control command requested. |
| arg | Indicates the data required for the command. |
| ext | Specifies an extension argument required by some device drivers. Its content, form, and use are determined by the individual driver. |
| flags | Indicates the address space of arg parameter. If the arg value is in kernel address space, flags should be specified as FKERNEL. Otherwise, it should be zero (drivers pass data that is in user space). |
| retval | Points to the location where the return value will be stored on successful return from the call. |
The fp_ioctlx kernel service can be called only from the process environment.
Upon successful completion, the fp_ioctlx kernel service returns 0. If unsuccessful, one of the values from the /usr/include/sys/errno.h file is returned. The ioctl subroutine contains valid errno values. This value will be stored in the retval parameter.