Use the VFIO driver instead of the UIO driver - Elastic Compute Service

Replace the UIO driver with the VFIO driver on ECS and ECS Bare Metal Instance (EBM) to fix DPDK runtime errors.

Prerequisites

Huge pages are configured on the instance.
DPDK is installed on the instance.

Background

DPDK applications on sixth-generation instance types (such as g6, c6, and r6) and later may encounter runtime errors. For example, pktgen-dpdk may fail to detect the NIC bound to the igb_uio driver. If you see the following error, replace the UIO driver with the VFIO driver.

EAL: eal_parse_sysfs_value(): cannot open sysfs value /sys/bus/pci/devices/0000:00:06.0/uio/uio0/portio/port0/start

Procedure

Connect to your ECS or EBM instance. See Log on to a Linux instance using Workbench.
Check the GRUB configuration.
```
cat /proc/cmdline
```
- If the output includes intel_iommu=on but not iommu=pt, skip to Step 4.
- Otherwise, go to Step 3 to add the parameter.
  
  In the following example, the output includes neither intel_iommu=on nor iommu=pt, so intel_iommu=on must be added.
Add intel_iommu=on to /etc/default/grub.
1. Open the file.
```
sudo vim /etc/default/grub
```
2. Press i to enter insert mode. Add intel_iommu=on to the GRUB_CMDLINE_LINUX parameter. Save and close the file.
  
  Example of the modified configuration:
3. Apply the configuration.
```
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
```
4. Restart the instance and reconnect after it starts.
```
reboot
```
  Warning
  The restart operation stops the instance for a short period of time and may interrupt services that are running on the instance. We recommend that you restart the instance during off-peak hours.

Load the VFIO and VFIO-PCI drivers.

sudo modprobe vfio && \
sudo modprobe vfio-pci

Enable noiommu_mode.

sudo bash -c 'echo 1 > /sys/module/vfio/parameters/enable_unsafe_noiommu_mode'

Get the bus-info value of the NIC.
```
ethtool -i ethX
```
Replace ethX with the target NIC ID. Example for eth1:
Bind the NIC to the vfio-pci driver. Navigate to the usertools directory in your DPDK installation directory and run:
```
sudo ./dpdk-devbind.py -b vfio-pci 0000:00:06.0
```
Note
Replace 0000:00:06.0 with the actual bus-info value of your NIC.

Run ./dpdk-devbind.py --status to verify. The following output shows 0000:00:06.0 bound to vfio-pci:
Start the DPDK application. Navigate to the build/app directory in your DPDK installation directory and run the command for your version.
- For DPDK 18.02 and later:
```
sudo ./testpmd -w 0000:00:06.0 -c 0x3 -- --total-num-mbufs=2048 -ai
```
- For versions earlier than DPDK 18.02:
```
sudo ./testpmd -w 0000:00:06.0 -c 0x3 -- --total-num-mbufs=2048 --disable-hw-vlan -ai
```
Note
-w 0000:00:06.0 specifies the NIC. total-num-mbufs=2048 must match your huge page size. Replace both with your actual values.

Example of a running DPDK application: