12. Driver for VM Emulated Devices

The DPDK EM poll mode driver supports the following emulated devices:

  • qemu-kvm emulated Intel® 82540EM Gigabit Ethernet Controller (qemu e1000 device)
  • VMware* emulated Intel® 82545EM Gigabit Ethernet Controller
  • VMware emulated Intel® 8274L Gigabit Ethernet Controller.

12.1. Validated Hypervisors

The validated hypervisors are:

  • KVM (Kernel Virtual Machine) with Qemu, version 0.14.0
  • KVM (Kernel Virtual Machine) with Qemu, version 0.15.1
  • VMware ESXi 5.0, Update 1

12.3. Setting Up a KVM Virtual Machine

The following describes a target environment:

  • Host Operating System: Fedora 14
  • Hypervisor: KVM (Kernel Virtual Machine) with Qemu version, 0.14.0
  • Guest Operating System: Fedora 14
  • Linux Kernel Version: Refer to the DPDK Getting Started Guide
  • Target Applications: testpmd

The setup procedure is as follows:

  1. Download qemu-kvm-0.14.0 from http://sourceforge.net/projects/kvm/files/qemu-kvm/ and install it in the Host OS using the following steps:

    When using a recent kernel (2.6.25+) with kvm modules included:

    tar xzf qemu-kvm-release.tar.gz cd qemu-kvm-release
./configure --prefix=/usr/local/kvm
make
sudo make install
sudo /sbin/modprobe kvm-intel

    When using an older kernel or a kernel from a distribution without the kvm modules, you must download (from the same link), compile and install the modules yourself:

    tar xjf kvm-kmod-release.tar.bz2
cd kvm-kmod-release
./configure
make
sudo make install
sudo /sbin/modprobe kvm-intel

    Note that qemu-kvm installs in the /usr/local/bin directory.

    For more details about KVM configuration and usage, please refer to: http://www.linux-kvm.org/page/HOWTO1.

  2. Create a Virtual Machine and install Fedora 14 on the Virtual Machine. This is referred to as the Guest Operating System (Guest OS).

  3. Start the Virtual Machine with at least one emulated e1000 device.

    Note

    The Qemu provides several choices for the emulated network device backend. Most commonly used is a TAP networking backend that uses a TAP networking device in the host. For more information about Qemu supported networking backends and different options for configuring networking at Qemu, please refer to:

    — http://www.linux-kvm.org/page/Networking

    — http://wiki.qemu.org/Documentation/Networking

    — http://qemu.weilnetz.de/qemu-doc.html

    For example, to start a VM with two emulated e1000 devices, issue the following command:

    /usr/local/kvm/bin/qemu-system-x86_64 -cpu host -smp 4 -hda qemu1.raw -m 1024
-net nic,model=e1000,vlan=1,macaddr=DE:AD:1E:00:00:01
-net tap,vlan=1,ifname=tapvm01,script=no,downscript=no
-net nic,model=e1000,vlan=2,macaddr=DE:AD:1E:00:00:02
-net tap,vlan=2,ifname=tapvm02,script=no,downscript=no

    where:

    — -m = memory to assign

    — -smp = number of smp cores

    — -hda = virtual disk image

    This command starts a new virtual machine with two emulated 82540EM devices, backed up with two TAP networking host interfaces, tapvm01 and tapvm02.

    # ip tuntap show
tapvm01: tap
tapvm02: tap

  4. Configure your TAP networking interfaces using ip/ifconfig tools.

  5. Log in to the guest OS and check that the expected emulated devices exist:

    # lspci -d 8086:100e
00:04.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 03)
00:05.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 03)

  6. Install the DPDK and run testpmd.

12.4. Known Limitations of Emulated Devices

The following are known limitations:

  1. The Qemu e1000 RX path does not support multiple descriptors/buffers per packet. Therefore, rte_mbuf should be big enough to hold the whole packet. For example, to allow testpmd to receive jumbo frames, use the following:

    testpmd [options] – –mbuf-size=<your-max-packet-size>

  2. Qemu e1000 does not validate the checksum of incoming packets.

  3. Qemu e1000 only supports one interrupt source, so link and Rx interrupt should be exclusive.

  4. Qemu e1000 does not support interrupt auto-clear, application should disable interrupt immediately when woken up.