MC_IOCTL(9E) Driver Entry Points MC_IOCTL(9E)


mc_ioctl - device specific I/O control operation


#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

prefix_m_ioctl(void *driver, queue_t *wq, mblk_t *mp);


illumos DDI Specific


driver A pointer to the driver's private data that was passed in via the
m_pdata member of the mac_register(9S) structure to the
mac_register(9F) function.

wq A pointer to a STREAMS write-side queue that the ioctl request was
received upon.

mp A pointer to a message block structure that contains the I/O
control request.


The mc_ioctl() entry point is an optional GLDv3 entry point. It provides a
means for device-specific I/O control operations to be initiated. In
general, this entry point is not recommended for most devices and is

The I/O control interface is not like a traditional character or block
device's ioctl(9E) entry point, rather it is a STREAMS-based I/O control
operation. The data pointer of the mp argument is a iocblk(9S) structure.
After handling the message, the driver will need to reply to the message,
which is usually done by using the miocack(9F) and miocnak(9F) functions to
prepare mp.

The device driver can access its soft state by casting the value pointed to
in driver. The driver should be careful and ensure that it performs any
necessary locking to access members of that structure while processing the
I/O control operation.


Return information is not conveyed by the return value of this function,
rather it is encoded in the iocblk(9S) structure in the mp argument.


The following example shows how a device driver might structure its
mc_ioctl() entry point.

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

* Note, this example merely shows the structure of this function. It does not
* actively handle any device-specific ioctls and instead returns failure for
* every one. This is the most common case. Note, miocnak(9F) takes care of
* calling putnext(9F) for us.
static void
example_m_ioctl(void *arg, queue_t *wq, mblk_t *mp)
miocnak(wq, mp, 0, EINVAL);


ioctl(9E), mac(9E), put(9E), mac_register(9F), miocack(9F), miocnak(9F),
putnext(9F), iocblk(9S), mac_register(9S)

Writing Device Drivers.

STREAMS Programming Guide.

OmniOS May 31, 2016 OmniOS