Common Problems and Solutions Activating Virtual Functions

If it fails with the following error, it is most likely because the Link-Virtualization™ Software driver is not loaded.

echo $NUMVF > /sys/bus/pci/devices/$DEV/sriov_numvfs
-bash: echo: write error: No such file or directory

To check whether the Link-Virtualization™ Software driver is loaded, run:

lsmod |grep nt3

Load the driver if it is not loaded.

 /opt/napatech3/bin/ntload.sh
Loading nt3gd driver                                        [Done]
Creating driver device file                                 [Done]
Loading nt3gd_netdev driver                                 [Done]
Creating driver device file                                 [Done]

It may fail with the following error in some old servers or some servers with old BIOS versions.

echo $NUMVF > /sys/bus/pci/devices/$DEV/sriov_numvfs
-bash: echo: write error: Cannot allocate memory

You will find the following error messages in /var/log/dmesg:

nt3gd 0000:03:00.0: sriov configure (res=3)
nt3gd 0000:03:00.0: not enough MMIO resources for SR-IOV
nt3gd 0000:03:00.0: sriov configure (res=-12)

It is because the BIOS is not providing enough MMIO space for VFs. You may have to upgrade BIOS. This issue can also be resolved by adding the kernel parameter, pci=realloc. It enables reallocating PCI bridge resources to accommodate required resource. Edit the /etc/default/grub file and append the following kernel parameter to the existing GRUB_CMDLINE_LINUX line.

pci=realloc

Update grub and reboot the server.

grub2-mkconfig -o /boot/grub2/grub.cfg
reboot

Verify the kernel parameters.

cat /proc/cmdline

It may fail with the following error.

echo $NUMVF > /sys/bus/pci/devices/$DEV/sriov_numvfs
-bash: /sys/bus/pci/devices/<device_ID>/sriov_numvfs: cannot overwrite existing file

It is most likely because the noclobber option is enabled by default. To check this option, run:

set -o | grep noclobber

An output example

noclobber       on

This means that overwriting the contents of a file using shell redirection ( the > and >> operators) is not allowed in a command line interface. To disable the noclobber option, run:

set +o noclobber

Or you can bypass the noclobber restriction by using the >| redirection operator.

echo $NUMVF >| /sys/bus/pci/devices/$DEV/sriov_numvfs