6. Known Issues and Limitations

This section describes known issues with the DPDK software.

6.2. Pause Frame Forwarding does not work properly on igb

Title Pause Frame forwarding does not work properly on igb
Reference # IXA00384637
Description For igb devices rte_eth_flow_ctrl_set is not working as expected. Pause frames are always forwarded on igb, regardless of the RFCE, MPMCF and DPF registers.
Implication Pause frames will never be rejected by the host on 1G NICs and they will always be forwarded.
Resolution/ Workaround There is no workaround available.
Affected Environment/ Platform All
Driver/Module Poll Mode Driver (PMD)

6.3. In packets provided by the PMD, some flags are missing

Title In packets provided by the PMD, some flags are missing
Reference # 3
Description In packets provided by the PMD, some flags are missing. The application does not have access to information provided by the hardware (packet is broadcast, packet is multicast, packet is IPv4 and so on).
Implication The “ol_flags” field in the “rte_mbuf” structure is not correct and should not be used.
Resolution The application has to parse the Ethernet header itself to get the information, which is slower.
Affected Environment/ Platform All
Driver/Module Poll Mode Driver (PMD)

6.4. The rte_malloc library is not fully implemented

Title The rte_malloc library is not fully implemented
Reference # 6
Description The rte_malloc library is not fully implemented.
Implication All debugging features of rte_malloc library described in architecture documentation are not yet implemented.
Resolution No workaround available.
Affected Environment/ Platform All
Driver/Module rte_malloc

6.5. HPET reading is slow

Title HPET reading is slow
Reference # 7
Description Reading the HPET chip is slow.
Implication An application that calls “rte_get_hpet_cycles()” or “rte_timer_manage()” runs slower.
Resolution The application should not call these functions too often in the main loop. An alternative is to use the TSC register through “rte_rdtsc()” which is faster, but specific to an lcore and is a cycle reference, not a time reference.
Affected Environment/ Platform All
Driver/Module Environment Abstraction Layer (EAL)

6.6. HPET timers do not work on the Osage customer reference platform

Title HPET timers do not work on the Osage customer reference platform
Reference # 17
Description HPET timers do not work on the Osage customer reference platform which includes an Intel® Xeon® processor 5500 series processor) using the released BIOS from Intel.
Implication On Osage boards, the implementation of the “rte_delay_us()” function must be changed to not use the HPET timer.
Resolution This can be addressed by building the system with the “CONFIG_RTE_LIBEAL_USE_HPET=n” configuration option or by using the –no-hpet EAL option.
Affected Environment/ Platform

The Osage customer reference platform.

Other vendor platforms with Intel® Xeon® processor 5500 series processors should work correctly, provided the BIOS supports HPET.

Driver/Module lib/librte_eal/common/include/rte_cycles.h

6.7. Not all variants of supported NIC types have been used in testing

Title Not all variants of supported NIC types have been used in testing
Reference # 28
Description

The supported network interface cards can come in a number of variants with different device ID’s. Not all of these variants have been tested with the Intel® DPDK.

The NIC device identifiers used during testing:

  • Intel® Ethernet Controller XL710 for 40GbE QSFP+ [8086:1584]
  • Intel® Ethernet Controller XL710 for 40GbE QSFP+ [8086:1583]
  • Intel® Ethernet Controller X710 for 10GbE SFP+ [8086:1572]
  • Intel® 82576 Gigabit Ethernet Controller [8086:10c9]
  • Intel® 82576 Quad Copper Gigabit Ethernet Controller [8086:10e8]
  • Intel® 82580 Dual Copper Gigabit Ethernet Controller [8086:150e]
  • Intel® I350 Quad Copper Gigabit Ethernet Controller [8086:1521]
  • Intel® 82599 Dual Fibre 10 Gigabit Ethernet Controller [8086:10fb]
  • Intel® Ethernet Server Adapter X520-T2 [8086: 151c]
  • Intel® Ethernet Controller X540-T2 [8086:1528]
  • Intel® 82574L Gigabit Network Connection [8086:10d3]
  • Emulated Intel® 82540EM Gigabit Ethernet Controller [8086:100e]
  • Emulated Intel® 82545EM Gigabit Ethernet Controller [8086:100f]
  • Intel® Ethernet Server Adapter X520-4 [8086:154a]
  • Intel® Ethernet Controller I210 [8086:1533]
Implication Risk of issues with untested variants.
Resolution Use tested NIC variants. For those supported Ethernet controllers, additional device IDs may be added to the software if required.
Affected Environment/ Platform All
Driver/Module Poll-mode drivers

6.8. Multi-process sample app requires exact memory mapping

Title Multi-process sample app requires exact memory mapping
Reference # 30
Description The multi-process example application assumes that it is possible to map the hugepage memory to the same virtual addresses in client and server applications. Occasionally, very rarely with 64-bit, this does not occur and a client application will fail on startup. The Linux “address-space layout randomization” security feature can sometimes cause this to occur.
Implication A multi-process client application fails to initialize.
Resolution See the “Multi-process Limitations” section in the Intel® DPDK Programmer’s Guide for more information.
Affected Environment/ Platform All
Driver/Module Multi-process example application

6.9. Packets are not sent by the 1 GbE/10 GbE SR-IOV driver when the source MAC address is not the MAC address assigned to the VF NIC

Title Packets are not sent by the 1 GbE/10 GbE SR-IOV driver when the source MAC address is not the MAC address assigned to the VF NIC
Reference # IXA00168379
Description The 1 GbE/10 GbE SR-IOV driver can only send packets when the Ethernet header’s source MAC address is the same as that of the VF NIC. The reason for this is that the Linux “ixgbe” driver module in the host OS has its anti-spoofing feature enabled.
Implication Packets sent using the 1 GbE/10 GbE SR-IOV driver must have the source MAC address correctly set to that of the VF NIC. Packets with other source address values are dropped by the NIC if the application attempts to transmit them.
Resolution/ Workaround Configure the Ethernet source address in each packet to match that of the VF NIC.
Affected Environment/ Platform All
Driver/Module 1 GbE/10 GbE VF Poll Mode Driver (PMD)

6.10. SR-IOV drivers do not fully implement the rte_ethdev API

Title SR-IOV drivers do not fully implement the rte_ethdev API
Reference # 59
Description

The SR-IOV drivers only supports the following rte_ethdev API functions:

  • rte_eth_dev_configure()
  • rte_eth_tx_queue_setup()
  • rte_eth_rx_queue_setup()
  • rte_eth_dev_info_get()
  • rte_eth_dev_start()
  • rte_eth_tx_burst()
  • rte_eth_rx_burst()
  • rte_eth_dev_stop()
  • rte_eth_stats_get()
  • rte_eth_stats_reset()
  • rte_eth_link_get()
  • rte_eth_link_get_no_wait()
Implication Calling an unsupported function will result in an application error.
Resolution/ Workaround Do not use other rte_ethdev API functions in applications that use the SR-IOV drivers.
Affected Environment/ Platform All
Driver/Module VF Poll Mode Driver (PMD)

6.11. PMD does not work with –no-huge EAL command line parameter

Title PMD does not work with –no-huge EAL command line parameter
Reference # IXA00373461
Description Currently, the DPDK does not store any information about memory allocated by malloc() (for example, NUMA node, physical address), hence PMD drivers do not work when the –no-huge command line parameter is supplied to EAL.
Implication Sending and receiving data with PMD will not work.
Resolution/ Workaround Use huge page memory or use VFIO to map devices.
Affected Environment/ Platform Systems running the DPDK on Linux
Driver/Module Poll Mode Driver (PMD)

6.12. Some hardware off-load functions are not supported by the VF Driver

Title Some hardware off-load functions are not supported by the VF Driver
Reference # IXA00378813
Description

Currently, configuration of the following items is not supported by the VF driver:

  • IP/UDP/TCP checksum offload
  • Jumbo Frame Receipt
  • HW Strip CRC
Implication Any configuration for these items in the VF register will be ignored. The behavior is dependant on the current PF setting.
Resolution/ Workaround For the PF (Physical Function) status on which the VF driver depends, there is an option item under PMD in the config file. For others, the VF will keep the same behavior as PF setting.
Affected Environment/ Platform All
Driver/Module VF (SR-IOV) Poll Mode Driver (PMD)

6.13. Kernel crash on IGB port unbinding

Title Kernel crash on IGB port unbinding
Reference # 74
Description Kernel crash may occur when unbinding 1G ports from the igb_uio driver, on 2.6.3x kernels such as shipped with Fedora 14.
Implication Kernel crash occurs.
Resolution/ Workaround Use newer kernels or do not unbind ports.
Affected Environment/ Platform 2.6.3x kernels such as shipped with Fedora 14
Driver/Module IGB Poll Mode Driver (PMD)

6.15. Discrepancies between statistics reported by different NICs

Title Discrepancies between statistics reported by different NICs
Reference # IXA00378113
Description Gigabit Ethernet devices from Intel include CRC bytes when calculating packet reception statistics regardless of hardware CRC stripping state, while 10-Gigabit Ethernet devices from Intel do so only when hardware CRC stripping is disabled.
Implication There may be a discrepancy in how different NICs display packet reception statistics.
Resolution/ Workaround None
Affected Environment/ Platform All
Driver/Module Poll Mode Driver (PMD)

6.16. Error reported opening files on DPDK initialization

Title Error reported opening files on DPDK initialization
Reference # 91
Description On DPDK application startup, errors may be reported when opening files as part of the initialization process. This occurs if a large number, for example, 500 or more, or if hugepages are used, due to the per-process limit on the number of open files.
Implication The DPDK application may fail to run.
Resolution/ Workaround If using 2 MB hugepages, consider switching to a fewer number of 1 GB pages. Alternatively, use the “ulimit” command to increase the number of files which can be opened by a process.
Affected Environment/ Platform All
Driver/Module Environment Abstraction Layer (EAL)

6.17. Intel® QuickAssist Technology sample application does not work on a 32-bit OS on Shumway

Title Intel® QuickAssist Technology sample applications does not work on a 32- bit OS on Shumway
Reference # 93
Description The Intel® Communications Chipset 89xx Series device does not fully support NUMA on a 32-bit OS. Consequently, the sample application cannot work properly on Shumway, since it requires NUMA on both nodes.
Implication The sample application cannot work in 32-bit mode with emulated NUMA, on multi-socket boards.
Resolution/ Workaround There is no workaround available.
Affected Environment/ Platform Shumway
Driver/Module All

6.18. IEEE1588 support possibly not working with an Intel® Ethernet Controller I210 NIC

Title IEEE1588 support may not work with an Intel® Ethernet Controller I210 NIC
Reference # IXA00380285
Description IEEE1588 support is not working with an Intel® Ethernet Controller I210 NIC.
Implication IEEE1588 packets are not forwarded correctly by the Intel® Ethernet Controller I210 NIC.
Resolution/ Workaround There is no workaround available.
Affected Environment/ Platform All
Driver/Module IGB Poll Mode Driver

6.19. Differences in how different Intel NICs handle maximum packet length for jumbo frame

Title Differences in how different Intel NICs handle maximum packet length for jumbo frame
Reference # 96
Description 10 Gigabit Ethernet devices from Intel do not take VLAN tags into account when calculating packet size while Gigabit Ethernet devices do so for jumbo frames.
Implication When receiving packets with VLAN tags, the actual maximum size of useful payload that Intel Gigabit Ethernet devices are able to receive is 4 bytes (or 8 bytes in the case of packets with extended VLAN tags) less than that of Intel 10 Gigabit Ethernet devices.
Resolution/ Workaround Increase the configured maximum packet size when using Intel Gigabit Ethernet devices.
Affected Environment/ Platform All
Driver/Module Poll Mode Driver (PMD)

6.20. Binding PCI devices to igb_uio fails on Linux* kernel 3.9 when more than one device is used

Title Binding PCI devices to igb_uio fails on Linux* kernel 3.9 when more than one device is used
Reference # 97
Description A known bug in the uio driver included in Linux* kernel version 3.9 prevents more than one PCI device to be bound to the igb_uio driver.
Implication The Poll Mode Driver (PMD) will crash on initialization.
Resolution/ Workaround Use earlier or later kernel versions, or apply the following patch .
Affected Environment/ Platform Linux* systems with kernel version 3.9
Driver/Module igb_uio module

6.21. GCC might generate Intel® AVX instructions forprocessors without Intel® AVX support

Title Gcc might generate Intel® AVX instructions for processors without Intel® AVX support
Reference # IXA00382439
Description When compiling Intel® DPDK (and any DPDK app), gcc may generate Intel® AVX instructions, even when the processor does not support Intel® AVX.
Implication Any DPDK app might crash while starting up.
Resolution/ Workaround Either compile using icc or set EXTRA_CFLAGS=’-O3’ prior to compilation.
Affected Environment/ Platform Platforms which processor does not support Intel® AVX.
Driver/Module Environment Abstraction Layer (EAL)

6.22. Ethertype filter could receive other packets (non-assigned) in Niantic

Title Ethertype filter could receive other packets (non-assigned) in Niantic
Reference # IXA00169017
Description

On Intel® Ethernet Controller 82599EB:

When Ethertype filter (priority enable) was set, unmatched packets also could be received on the assigned queue, such as ARP packets without 802.1q tags or with the user priority not equal to set value.

Launch the testpmd by disabling RSS and with multiply queues, then add the ethertype filter like: “add_ethertype_filter 0 ethertype 0x0806 priority enable 3 queue 2 index 1”, and then start forwarding.

When sending ARP packets without 802.1q tag and with user priority as non-3 by tester, all the ARP packets can be received on the assigned queue.

Implication The user priority comparing in Ethertype filter cannot work probably. It is the NIC’s issue due to the response from PAE: “In fact, ETQF.UP is not functional, and the information will be added in errata of 82599 and X540.”
Resolution/ Workaround None
Affected Environment/ Platform All
Driver/Module Poll Mode Driver (PMD)

6.25. Devices bound to igb_uio with VT-d enabled do not work on Linux* kernel 3.15-3.17

Title Devices bound to igb_uio with VT-d enabled do not work on Linux* kernel 3.15-3.17
Description
When VT-d is enabled (iommu=pt intel_iommu=on), devices are 1:1 mapped. In the Linux* kernel unbinding devices from drivers removes that mapping which result in IOMMU errors.
Introduced in Linux kernel 3.15 commit, solved in Linux kernel 3.18 commit.
Implication
Devices will not be allowed to access memory, resulting in following kernel errors:
dmar: DRHD: handling fault status reg 2
dmar: DMAR:[DMA Read] Request device [02:00.0] fault addr a0c58000
DMAR:[fault reason 02] Present bit in context entry is clear
Resolution/ Workaround
Use earlier or later kernel versions, or avoid driver binding on boot by blacklisting the driver modules.
ie. in the case of ixgbe, we can pass the kernel command line option:
modprobe.blacklist=ixgbe
This way we do not need to unbind the device to bind it to igb_uio.
Affected Environment/ Platform Linux* systems with kernel versions 3.15 to 3.17
Driver/Module igb_uio module

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