Commit 271225fd authored by Robert Schlabbach's avatar Robert Schlabbach Committed by Tony Nguyen
Browse files

ixgbe: Document how to enable NBASE-T support 

Commit a296d665 ("ixgbe: Add ethtool support to enable 2.5 and 5.0
Gbps support") introduced suppression of the advertisement of NBASE-T
speeds by default, according to Todd Fujinaka to accommodate customers
with network switches which could not cope with advertised NBASE-T
speeds, as posted in the E1000-devel mailing list:

https://sourceforge.net/p/e1000/mailman/message/37106269/



However, the suppression was not documented at all, nor was how to
enable NBASE-T support.

Properly document the NBASE-T suppression and how to enable NBASE-T
support.

Fixes: a296d665 ("ixgbe: Add ethtool support to enable 2.5 and 5.0 Gbps support")
Reported-by: default avatarRobert Schlabbach <robert_s@gmx.net>
Signed-off-by: default avatarRobert Schlabbach <robert_s@gmx.net>
Signed-off-by: default avatarTony Nguyen <anthony.l.nguyen@intel.com>
parent 0182d1f3

Documentation/networking/device_drivers/ethernet/intel/ixgbe.rst

+16 −0
Original line number Diff line number Diff line
@@ -440,6 +440,22 @@ NOTE: For 82599-based network connections, if you are enabling jumbo frames in 
a virtual function (VF), jumbo frames must first be enabled in the physical

function (PF). The VF MTU setting cannot be larger than the PF MTU.



NBASE-T Support

---------------

The ixgbe driver supports NBASE-T on some devices. However, the advertisement

of NBASE-T speeds is suppressed by default, to accommodate broken network

switches which cannot cope with advertised NBASE-T speeds. Use the ethtool

command to enable advertising NBASE-T speeds on devices which support it::



  ethtool -s eth? advertise 0x1800000001028



On Linux systems with INTERFACES(5), this can be specified as a pre-up command

in /etc/network/interfaces so that the interface is always brought up with

NBASE-T support, e.g.::



  iface eth? inet dhcp

       pre-up ethtool -s eth? advertise 0x1800000001028 || true



Generic Receive Offload, aka GRO

--------------------------------

The driver supports the in-kernel software implementation of GRO. GRO has

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

+4 −0
Original line number Diff line number Diff line
@@ -5531,6 +5531,10 @@ static int ixgbe_non_sfp_link_config(struct ixgbe_hw *hw) 
	if (!speed && hw->mac.ops.get_link_capabilities) {

		ret = hw->mac.ops.get_link_capabilities(hw, &speed,

							&autoneg);

		/* remove NBASE-T speeds from default autonegotiation

		 * to accommodate broken network switches in the field

		 * which cannot cope with advertised NBASE-T speeds

		 */

		speed &= ~(IXGBE_LINK_SPEED_5GB_FULL |

			   IXGBE_LINK_SPEED_2_5GB_FULL);

	}