igbvf.txt: Add igbvf Documentation

Adds documentation for the igbvf (igb virtual function driver).

  v2:
   - Removed trailing white space
   - Removed Ethtool version info
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/igbvf.txt

+Linux* Base Driver for Intel(R) Network Connection
+==================================================
+
+Intel Gigabit Linux driver.
+Copyright(c) 1999 - 2010 Intel Corporation.
+
+Contents
+========
+
+- Identifying Your Adapter
+- Additional Configurations
+- Support
+
+This file describes the igbvf Linux* Base Driver for Intel Network Connection.
+
+The igbvf driver supports 82576-based virtual function devices that can only
+be activated on kernels that support SR-IOV. SR-IOV requires the correct
+platform and OS support.
+
+The igbvf driver requires the igb driver, version 2.0 or later. The igbvf
+driver supports virtual functions generated by the igb driver with a max_vfs
+value of 1 or greater. For more information on the max_vfs parameter refer
+to the README included with the igb driver.
+
+The guest OS loading the igbvf driver must support MSI-X interrupts.
+
+This driver is only supported as a loadable module at this time.  Intel is
+not supplying patches against the kernel source to allow for static linking
+of the driver.  For questions related to hardware requirements, refer to the
+documentation supplied with your Intel Gigabit adapter.  All hardware
+requirements listed apply to use with Linux.
+
+Instructions on updating ethtool can be found in the section "Additional
+Configurations" later in this document.
+
+VLANs: There is a limit of a total of 32 shared VLANs to 1 or more VFs.
+
+Identifying Your Adapter
+========================
+
+The igbvf driver supports 82576-based virtual function devices that can only
+be activated on kernels that support SR-IOV.
+
+For more information on how to identify your adapter, go to the Adapter &
+Driver ID Guide at:
+
+    http://support.intel.com/support/go/network/adapter/idguide.htm
+
+For the latest Intel network drivers for Linux, refer to the following
+website.  In the search field, enter your adapter name or type, or use the
+networking link on the left to search for your adapter:
+
+    http://downloadcenter.intel.com/scripts-df-external/Support_Intel.aspx
+
+Additional Configurations
+=========================
+
+  Ethtool
+  -------
+  The driver utilizes the ethtool interface for driver configuration and
+  diagnostics, as well as displaying statistical information.
+
+  http://sourceforge.net/projects/gkernel.
+
+Support
+=======
+
+For general information, go to the Intel support website at:
+
+    http://support.intel.com
+
+or the Intel Wired Networking project hosted by Sourceforge at:
+
+    http://sourceforge.net/projects/e1000
+
+If an issue is identified with the released source code on the supported
+kernel with a supported adapter, email the specific information related
+to the issue to e1000-devel@lists.sf.net