1.\" 2.\" This file and its contents are supplied under the terms of the 3.\" Common Development and Distribution License ("CDDL"), version 1.0. 4.\" You may only use this file in accordance with the terms of version 5.\" 1.0 of the CDDL. 6.\" 7.\" A full copy of the text of the CDDL should have accompanied this 8.\" source. A copy of the CDDL is also available via the Internet at 9.\" http://www.illumos.org/license/CDDL. 10.\" 11.\" 12.\" Copyright 2016 Joyent, Inc. 13.\" 14.Dd June 02, 2016 15.Dt MAC_MAXSDU_UPDATE 9F 16.Os 17.Sh NAME 18.Nm mac_maxsdu_update 19.Nd indicate that a device's maximum data size has changed 20.Sh SYNOPSIS 21.In sys/mac_provider.h 22.Ft int 23.Fo mac_maxsdu_update 24.Fa "mac_handle_t mh" 25.Fa "uint_t sdu" 26.Fc 27.Sh INTERFACE LEVEL 28illumos DDI specific 29.Sh PARAMETERS 30.Bl -tag -width Fa 31.It Fa mh 32The MAC handle obtained from a call to 33.Xr mac_register 9F . 34.It Fa sdu 35An integer representing the maximum size data payload. 36.El 37.Sh DESCRIPTION 38The 39.Fn mac_maxsdu_update 40function is used to inform the MAC layer that the device represented by 41the handle 42.Fa mh 43has changed the largest size frame that it can transmit, also known as 44its Send Data Unit (SDU). 45This should be called when the device's MTU has been requested to be changed 46when a driver's 47.Xr mc_setprop 9E 48entry point has been called with the property 49.Sy MAC_PROP_MTU 50or some other device-related event occurring. 51.Pp 52The 53.Fa sdu 54represents the size of the largest payload ignoring the size of its own 55headers or any margin. 56For example, for an Ethernet-based device, this size should not include the 57Ethernet header or any VLAN tags. 58.Pp 59Through VNICs and other virtual data links, many different devices may 60be using a single physical device and have their own MTUs. 61The system takes care of those concerns and will not ask a device driver to 62update the MTU without verifying this. 63.Sh RETURN VALUES 64Upon successful completion, the 65.Fn mac_maxsdu_update 66function returns 67.Sy 0 . 68Otherwise, a non-negative error is returned. 69.Sh EXAMPLES 70For an example of how a device driver should use the 71.Fn mac_maxsdu_update 72function, see the 73.Sx EXAMPLES 74section in 75.Xr mc_setprop 9E . 76.Sh ERRORS 77The 78.Fn max_maxsdu_update 79function may fail if: 80.Bl -tag -width Er 81.It Er EINVAL 82The specified 83.Fa sdu 84is lower than the minimum SDU of the device. 85.El 86.Sh SEE ALSO 87.Xr mac 9E , 88.Xr mc_setprop 9E , 89.Xr mac_register 9F 90