QSFP to SFP+ adapter and Chelsio T580 settings

[rogeroger]

When using a QSFP to SFP+ adapter with the Chelsio T580 (as described here) , do I have to use mode 2 or mode 3 (mode 1 being 2x40Gbe)?
Mode 2: SPIDER (4X10G): In this mode, port 0 functions as 4 10Gbps links and port 1 is disabled
Mode 3: QSA (2X10G): This mode adds support for QSA (QSFP to SFP+) modules, enabling smooth,
cost-effective, connections between 40 Gigabit Ethernet adapters and 1 or 10 Gigabit
Ethernet networks using existing SFP+ based cabling. The port farthest from the motherboard
will appear as the first network interface (Port 0).

 

[RTM]

When using a QSFP to SFP+ adapter with the Chelsio T580 (as described here) , do I have to use mode 2 or mode 3 (mode 1 being 2x40Gbe)?
Mode 2: SPIDER (4X10G): In this mode, port 0 functions as 4 10Gbps links and port 1 is disabled
Mode 3: QSA (2X10G): This mode adds support for QSA (QSFP to SFP+) modules, enabling smooth,
cost-effective, connections between 40 Gigabit Ethernet adapters and 1 or 10 Gigabit
Ethernet networks using existing SFP+ based cabling. The port farthest from the motherboard
will appear as the first network interface (Port 0).

This is nothing more than an educated guess, but mode 3 sounds like what you want.