Copyright 2007 Sun Microsystems

1. Introduction
   1.1. New Max Frame Size Property For NIU Hybrid IO

   1.2. Name of Document Author/Supplier: Michael Speer

   1.3. Date of This Document: 08/26/2008

   1.4. Email Aliases:
    	1.5.2. Responsible Engineer: Michael.Speer@Sun.COM, 
	1.5.3. Interest List: Raghuram.Kothakota@Sun.COM, Sriharsha.Basavapatna@Sun.COM

2. Project Summary
   2.1. Project Description:
	This project updates the NIU device binding and MD properties to add a new
        property which will allow a guest domain hybyrid NIU (nxge) device to enable
        jumbo frame operation.

3. Technical Description:

    3.1. Details:

	3.1.1 Introduction:
        The hybrid mode nxge device can be dynamically assigned to a guest
        domain.  It consists of a Virtual Region and a set of RX and TX channels.
        It is plugged directly into the vnet device that is operating in the
        hybrid I/O mode. The traditional interfaces GLDv3 layer to configure,
        operate and move data between the vnet and the hybrid nxge device are
        not utilized.  Instead, the interface in [1] is utilized.  To configure,
        the hybrid NIU device properly for jumbo frames, it must be done at
        driver attach time. Additionally, when the hybrid NIU's device is created
        and graphted onto the Solaris device tree, the vnet's DDS[2] service knows
        whether to add to the device node the property to configure jummbo frame
        operation or not.
        
        3.1.2 Problem Statement:
        The nxge driver configures operational parameters such as jumbo frames
        today as a device property from the device's .conf file or via the
        Brussels m_setop/m_getop interface.  In the guest domain none of these
        interfaces are available to the guest domain Hybrid NIU (nxge) device
        driver.  Hence, a solution is needed to enable proper jumbo frame
        operation that does not require large changes and is portable to Solaris
        10 Update as well (some interfaces e.g. Brussels is not available in
        Solaris 10 Update).
        
        3.1.3 Proposal:
        In order to support jumbo frames in the guest domain via the Hybrid mode
        nxge device, the device needs the information about the maxframesize that
        is currently programmed in the MAC.  To provide this information to the
        hybrid mode nxge device node, we are proposing an optional property named
        max-frame-size that reflects the currently programmed value.  At the time
        the vnet's DDS creates the device node for nxge before it is attached
        in the guest domain, it will add this property to the device node.  Then,
        the driver will attach and configure properly.

    
    3.2. Interfaces:

	3.2.2 Exported Interfaces:

	Interface	 Classification		Comment
	=====================================================================

	"max-frame-size" Uncommitted		Optional encoded integer
                                                property of the NIU device



5. Reference Documents:

        [1] PSARC 2008/247 and associated materials

        [2] FWARC 2008/246 and associated materials

        [3] NIU Device Tree Bindings and Machine Description Definition

            niu-binding.txt

        [2] Initial N2 NIU binding case

            http://sac.eng/Archives/CaseLog/arc/FWARC/2006/556/materials/