Tribblix: manual page: mac_maxsdu

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

NAME

mac_maxsdu_update - indicate that a device's maximum data size has
changed

SYNOPSIS

#include <sys/mac_provider.h>

int
mac_maxsdu_update(mac_handle_t mh, uint_t sdu);

INTERFACE LEVEL

illumos DDI specific

PARAMETERS

mh The MAC handle obtained from a call to mac_register(9F).

sdu An integer representing the maximum size data payload.

DESCRIPTION

The mac_maxsdu_update() function is used to inform the MAC layer that
the device represented by the handle mh has changed the largest size
frame that it can transmit, also known as its Send Data Unit (SDU).
This should be called when the device's MTU has been requested to be
changed when a driver's mc_setprop(9E) entry point has been called with
the property MAC_PROP_MTU or some other device-related event occurring.

The sdu represents the size of the largest payload ignoring the size of
its own headers or any margin. For example, for an Ethernet-based
device, this size should not include the Ethernet header or any VLAN
tags.

Through VNICs and other virtual data links, many different devices may
be using a single physical device and have their own MTUs. The system
takes care of those concerns and will not ask a device driver to update
the MTU without verifying this.

RETURN VALUES

Upon successful completion, the mac_maxsdu_update() function returns 0.
Otherwise, a non-negative error is returned.

EXAMPLES

For an example of how a device driver should use the
mac_maxsdu_update() function, see the EXAMPLES section in
mc_setprop(9E).

ERRORS

The max_maxsdu_update() function may fail if:

EINVAL The specified sdu is lower than the minimum SDU of
the device.