Dell Intel PRO Family of Adapters - Manual (Page 96)

Parameter Name Valid
Range/Settings
Default Description
max_vfs 1 - 63 0 This parameter adds support for SR-IOV. It causes the driver to
spawn up to max_vfs worth of virtual function.
If the value is greater than 0, it will also force the VMDq para-
meter to be 1 or more.
NOTE: When either SR-IOV mode or VMDq mode is
enabled, hardware VLAN filtering and VLAN tag strip-
ping/insertion will remain enabled. Please remove the
old VLAN filter before the new VLAN filter is added. For
example:
ip link set eth0 vf 0 vlan 100
// set vlan 100 for VF 0
ip link set eth0 vf 0 vlan 0 //
Delete vlan 100
ip link set eth0 vf 0 vlan 200
// set a new vlan 200 for VF 0
The parameters for the driver are referenced by position. So, if
you have a dual port 82599-based adapter and you want N vir-
tual functions per port, you must specify a number for each port
with each parameter separated by a comma.
For example: modprobe ixgbe max_vfs=63,63
NOTE: If both 82598 and 82599-based adapters are
installed on the same machine, you must be careful in
loading the driver with the parameters. Depending on
system configuration, number of slots, etc., it is
impossible to predict in all cases where the positions
would be on the command line and the user will have to
specify zero in those positions occupied by an 82598
port.
With kernel 3.6, the driver supports the simultaneous usage of
max_vfs and DCB features, subject to the constraints described
below. Prior to kernel 3.6, the driver did not support the sim-
ultaneous operation of max_vfs > 0 and the DCB features (mul-
tiple traffic classes utilizing Priority Flow Control and Extended
Transmission Selection).
When DCB is enabled, network traffic is transmitted and
received through multiple traffic classes (packet buffers in the
NIC). The traffic is associated with a specific class based on pri-
ority, which has a value of 0 through 7 used in the VLAN tag.
When SR-IOV is not enabled, each traffic class is associated
with a set of RX/TX descriptor queue pairs. The number of
queue pairs for a given traffic class depends on the hardware
configuration. When SR-IOV is enabled, the descriptor queue
pairs are grouped into pools. The Physical Function (PF) and
each Virtual Function (VF) is allocated a pool of RX/TX
descriptor queue pairs. When multiple traffic classes are con-
figured (for example, DCB is enabled), each pool contains a
queue pair from each traffic class. When a single traffic class is
configured in the hardware, the pools contain multiple queue
pairs from the single traffic class.
The number of VFs that can be allocated depends on the num-
ber of traffic classes that can be enabled. The configurable num-
ber of traffic classes for each enabled VF is as follows: