MAC_REGISTER(9F) Kernel Functions for Drivers MAC_REGISTER(9F)


mac_register, mac_unregister - register and unregister a device driver from
the MAC framework


#include <sys/mac_provider.h>

mac_register(mac_register_t *mregp, mac_handle_t *mhp);

mac_unregister(mac_handle_t mh);


illumos DDI specific


mregp A pointer to a mac_register(9S) structure allocated by
calling mac_alloc(9F) and filled in by the device driver.

mhp A pointer to a driver-backed handle to the MAC framework.

mh The driver-backed handle to the MAC framework.


The mac_register() function is used to register an instance of a device
driver with the mac(9E) framework. Upon successfully calling the
mac_register() function, the device will start having its mac_callbacks(9S)
entry points called. The device driver should call this function during
it's attach(9E) entry point after the device has been configured and is set
up. For a more detailed explanation of the exact steps that the device
driver should take and where in the sequence of a driver's attach(9E) entry
point this function should be called, see the Registering with MAC section
of mac(9E).

The driver should provide a pointer to a mac_handle_t structure as the
second argument to the mac_register() function. This handle will be used
when the device driver needs to interact with the framework in various ways
throughout its life. It is also where the driver gets the mh argument for
calling the mac_unregister() function. It is recommended that the device
driver keep the handle around in its soft state structure for a given

If the call to the mac_register() function fails, the device driver should
unwind its attach(9E) entry point, tear down everything that it
initialized, and ultimately return an error from its attach(9E) entry

If the attach(9E) routine fails for some reason after the call to the
mac_register() function has succeeded, then the driver should call the
mac_unregister() function as part of unwinding all of its state.

When a driver is in its detach(9E) entry point, it should call the
mac_unregister() function immediately after draining any of its transmit
and receive resources that might have been given to the rest of the
operating system through DMA binding. See the MBLKS AND DMA section of
mac(9E) for more information. This should be done before the driver does
any tearing down. The call to the mac_unregister() function may fail.
This may happen because the networking stack is still using the device. In
such a case, the driver should fail the call to detach(9E) and return


The mac_register() function is generally only called from a driver's
attach(9E) entry point. The mac_unregister() function is generally only
called from a driver's attach(9E) and detach(9E) entry point. However,
both functions may be called from either user or kernel context.


Upon successful completion, the mac_register() and mac_unregister()
functions both return 0. Otherwise, they return an error number.


The following example shows how a device driver might call the
mac_register() function.

#include <sys/mac_provider.h>
#include <sys/mac_ether.h>

* The call to mac_register(9F) generally comes from the context of
* attach(9E). This function encapsulates setting up and initializing
* the mac_register_t structure and should be assumed to be called from
* attach.
* The exact set of callbacks and private properties will vary based
* upon the driver.

static char *example_priv_props[] = {

static mac_callbacks_t example_m_callbacks = {
.mc_start = example_m_start,
.mc_stop = example_m_stop,
.mc_setpromisc = example_m_setpromisc,
.mc_multicst = example_m_multicst,
.mc_unicst = example_m_unicst,
.mc_tx = example_m_tx,
.mc_ioctl = example_m_ioctl,
.mc_getcapab = example_m_getcapab,
.mc_getprop = example_m_getprop,
.mc_setprop = example_m_setprop,
.mc_propinfo = example_m_propinfo

static boolean_t
example_register_mac(example_t *ep)
int status;
mac_register_t *mac;

mac = mac_alloc(MAC_VERSION);
if (mac == NULL)
return (B_FALSE);

mac->m_type_ident = MAC_PLUGIN_IDENT_ETHER;
mac->m_driver = ep;
mac->m_dip = ep->ep_dev_info;
mac->m_src_addr = ep->ep_mac_addr;
mac->m_callbacks = &example_m_callbacks;
mac->m_min_sdu = 0;
mac->m_max_sdu = ep->ep_sdu;
mac->m_margin = VLAN_TAGSZ;
mac->m_priv_props = example_priv_props;

status = mac_register(mac, &ep->ep_mac_hdl);

return (status == 0);


The mac_register() function may fail if:

EEXIST A driver with the same name and instance already exists.

EINVAL There was something invalid with the device's
registration information. Some of the following reasons
may apply, this list is not exhaustive:

+o The mac_init_ops(9F) function was not called.

+o The specified mac plugin does not exist.

+o An invalid minor number was used.

+o The default unicast source address was incorrect.

+o The plugin specific private data was incorrect or

+o Plugin specific data was provided when none is

+o Required callback functions are not specified.

+o The system was unable to properly create minor

ENOSPC The mac(9E) framework was unable to allocate a minor
number for the device as they have all been exhausted.

The mac_unregister() function will fail if:

EBUSY The device is still in use.

ENOTEMPTY The flow table is not empty.

Note the set of errors for both the mac_register() and mac_unregister()
functions are not set in stone and may be expanded in future revisions. In
general, all errors should be handled by the device driver in similar ways
for these functions.


attach(9E), detach(9E), mac(9E), mac_alloc(9F), mac_init_ops(9F),
mac_callbacks(9S), mac_register(9S)

OmniOS July 17, 2023 OmniOS