38. Known Issues and Limitations in Legacy Releases

This section describes known issues with the DPDK software that aren’t covered in the version specific release notes sections.

38.2. Pause Frame Forwarding does not work properly on igb

Description:

For igb devices rte_eth_flow_ctrl_set does not work 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).

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

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/Workaround:

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).

38.4. The rte_malloc library is not fully implemented

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/Workaround:

No workaround available.

Affected Environment/Platform:

All.

Driver/Module:

rte_malloc.

38.5. HPET reading is slow

Description:

Reading the HPET chip is slow.

Implication:

An application that calls rte_get_hpet_cycles() or rte_timer_manage() runs slower.

Resolution/Workaround:

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).

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

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/Workaround:

This can be addressed by building the system with RTE_LIBEAL_USE_HPET unset 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/eal/include/rte_cycles.h

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

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 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/Workaround:

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

38.8. Multi-process sample app requires exact memory mapping

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/Workaround:

See the “Multi-process Limitations” section in the DPDK Programmer’s Guide for more information.

Affected Environment/Platform:

All.

Driver/Module:

Multi-process example application

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

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).

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

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).

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

Description:

Currently, the DPDK does not store any information about memory allocated by malloc() (for example, NUMA node, physical address), hence PMDs do not work when the --no-huge command line parameter is supplied to EAL. This happens when using non-IOMMU based UIO drivers (i.e. igb_uio or uio_pci_generic) or when IOVA mode is explicitly set to use physical addresses (via the --iova-mode=pa EAL parameter).

Implication:

Sending and receiving data with PMD will not work. Unit tests checking --no-huge operation will fail if there is a device bound to the PMD (eal_flags_n_opt_autotest, eal_flags_no_huge_autotest, eal_flags_vdev_opt_autotest, eal_flags_misc_autotest).

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).

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

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 dependent 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).

38.13. Kernel crash on IGB port unbinding

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).

38.15. Discrepancies between statistics reported by different NICs

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).

38.16. Error reported opening files on DPDK initialization

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).

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

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.

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

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).

38.19. GCC might generate Intel® AVX instructions for processors without Intel® AVX support

Description:

When compiling 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).

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

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 the following and then start forwarding:

add_ethertype_filter 0 ethertype 0x0806 priority enable 3 queue 2 index 1

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 a NIC’s issue due to the following: “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).

38.22. 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. I.e., 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.

38.23. VM power manager may not work on systems with more than 64 cores

Description:

When using VM power manager on a system with more than 64 cores, VM(s) should not use cores 64 or higher.

Implication:

VM power manager should not be used with VM(s) that are using cores 64 or above.

Resolution/Workaround:

Do not use cores 64 or above.

Affected Environment/Platform:

Platforms with more than 64 cores.

Driver/Module:

VM power manager application.

38.24. DPDK may not build on some Intel CPUs using clang < 3.7.0

Description:

When compiling DPDK with an earlier version than 3.7.0 of clang, CPU flags are not detected on some Intel platforms such as Intel Broadwell/Skylake (and possibly future CPUs), and therefore compilation fails due to missing intrinsics.

Implication:

DPDK will not build when using a clang version < 3.7.0.

Resolution/Workaround:

Use clang 3.7.0 or higher, or gcc.

Affected Environment/Platform:

Platforms with Intel Broadwell/Skylake using an old clang version.

Driver/Module:

Environment Abstraction Layer (EAL).

38.25. The last EAL argument is replaced by the program name in argv[]

Description:

The last EAL argument is replaced by program name in argv[] after eal_parse_args is called. This is the intended behavior but it causes the pointer to the last EAL argument to be lost.

Implication:

If the last EAL argument in argv[] is generated by a malloc function, changing it will cause memory issues when freeing the argument.

Resolution/Workaround:

An application should not consider the value in argv[] as unchanged.

Affected Environment/Platform:

ALL.

Driver/Module:

Environment Abstraction Layer (EAL).

38.26. I40e VF may not receive packets in the promiscuous mode

Description:

Promiscuous mode is not supported by the DPDK i40e VF driver when using the i40e Linux kernel driver as host driver.

Implication:

The i40e VF does not receive packets when the destination MAC address is unknown.

Resolution/Workaround:

Use a explicit destination MAC address that matches the VF.

Affected Environment/Platform:

All.

Driver/Module:

Poll Mode Driver (PMD).

38.27. uio_pci_generic module bind failed in X710/XL710/XXV710

Description:

The uio_pci_generic module is not supported by XL710, since the errata of XL710 states that the Interrupt Status bit is not implemented. The errata is the item #71 from the xl710 controller spec. The hw limitation is the same as other X710/XXV710 NICs.

Implication:

When use --bind=uio_pci_generic, the uio_pci_generic module probes device and check the Interrupt Status bit. Since it is not supported by X710/XL710/XXV710, it return a failed value. The statement that these products don’t support INTx masking, is indicated in the related linux kernel commit.

Resolution/Workaround:

Do not bind the uio_pci_generic module in X710/XL710/XXV710 NICs.

Affected Environment/Platform:

All.

Driver/Module:

Poll Mode Driver (PMD).

38.28. virtio tx_burst() function cannot do TSO on shared packets

Description:

The standard TX function of virtio driver does not manage shared packets properly when doing TSO. These packets should be read-only but the driver modifies them.

When doing TSO, the virtio standard expects that the L4 checksum is set to the pseudo header checksum in the packet data, which is different than the DPDK API. The driver patches the L4 checksum to conform to the virtio standard, but this solution is invalid when dealing with shared packets (clones), because the packet data should not be modified.

Implication:

In this situation, the shared data will be modified by the driver, potentially causing race conditions with the other users of the mbuf data.

Resolution/Workaround:

The workaround in the application is to ensure that the network headers in the packet data are not shared.

Affected Environment/Platform:

Virtual machines running a virtio driver.

Driver/Module:

Poll Mode Driver (PMD).

38.29. igb_uio legacy mode can not be used in X710/XL710/XXV710

Description:

X710/XL710/XXV710 NICs lack support for indicating INTx is asserted via the interrupt bit in the PCI status register. Linux deleted them from INTx support table. The related commit.

Implication:

When insmod igb_uio with intr_mode=legacy and test link status interrupt. Since INTx interrupt is not supported by X710/XL710/XXV710, it will cause Input/Output error when reading file descriptor.

Resolution/Workaround:

Do not bind igb_uio with legacy mode in X710/XL710/XXV710 NICs, or do not use kernel version >4.7 when you bind igb_uio with legacy mode.

Affected Environment/Platform:

ALL.

Driver/Module:

Poll Mode Driver (PMD).

38.30. igb_uio can not be used when running l3fwd-power

Description:

Link Status Change(LSC) interrupt and packet receiving interrupt are all enabled in l3fwd-power APP. Because of UIO only support one interrupt, so these two kinds of interrupt need to share one, and the receiving interrupt have the higher priority, so can’t get the right link status.

Implication:

When insmod igb_uio and running l3fwd-power APP, link status getting doesn’t work properly.

Resolution/Workaround:

Use vfio-pci when LSC and packet receiving interrupt enabled.

Affected Environment/Platform:

ALL.

Driver/Module:

igb_uio module.

38.31. Linux kernel 4.10.0 iommu attribute read error

Description:

When VT-d is enabled (iommu=pt intel_iommu=on), reading IOMMU attributes from /sys/devices/virtual/iommu/dmarXXX/intel-iommu/cap on Linux kernel 4.10.0 error. This bug is fixed in Linux commit a7fdb6e648fb, This bug is introduced in Linux commit 39ab9555c241,

Implication:

When binding devices to VFIO and attempting to run testpmd application, testpmd (and other DPDK applications) will not initialize.

Resolution/Workaround:

Use other linux kernel version. It only happens in linux kernel 4.10.0.

Affected Environment/Platform:

ALL OS of linux kernel 4.10.0.

Driver/Module:

vfio-pci module.

38.32. Netvsc driver and application restart

Description:

The Linux kernel uio_hv_generic driver does not completely shutdown and clean up resources properly if application using Netvsc PMD exits.

Implication:

When application using Netvsc PMD is restarted it can not complete initialization handshake sequence with the host.

Resolution/Workaround:

Either reboot the guest or remove and reinsert the uio_hv_generic module.

Affected Environment/Platform:

Linux Hyper-V.

Driver/Module:

uio_hv_generic module.

38.34. Restricted vdev ethdev operations supported in secondary process

Description

In current virtual device sharing model, Ethernet device data structure will be shared between primary and secondary process. Only those Ethernet device operations which based on it are workable in secondary process.

Implication

Some Ethernet device operations like device start/stop will be failed on virtual device in secondary process.

Affected Environment/Platform:

ALL.

Driver/Module:

Virtual Device Poll Mode Driver (PMD).

38.35. Kernel crash when hot-unplug igb_uio device while DPDK application is running

Description:

When device has been bound to igb_uio driver and application is running, hot-unplugging the device may cause kernel crash.

Reason:

When device is hot-unplugged, igb_uio driver will be removed which will destroy UIO resources. Later trying to access any UIO resource will cause kernel crash.

Resolution/Workaround:

If using DPDK for PCI HW hot-unplug, prefer to bind device with VFIO instead of IGB_UIO.

Affected Environment/Platform:

ALL.

Driver/Module:

igb_uio module.

38.36. AVX-512 support disabled

Description:

AVX-512 support has been disabled on some conditions.

On DPDK v18.11 AVX-512 is disabled for all GCC builds which reported to cause a performance drop.

On DPDK v19.02 AVX-512 disable scope is reduced to GCC and binutils version 2.30 based on information accrued from the GCC community defect.

Reason:

Generated AVX-512 code cause crash: https://bugs.dpdk.org/show_bug.cgi?id=97 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88096

Resolution/Workaround:

  • Update binutils to newer version than 2.30.

OR

  • Use different compiler, like clang for this case.

Affected Environment/Platform:

GCC and binutils version 2.30.

Driver/Module:

ALL.

38.37. Unsuitable IOVA mode may be picked as the default

Description

Not all kernel drivers and not all devices support all IOVA modes. EAL will attempt to pick a reasonable default based on a number of factors, but there may be cases where the default may be unsuitable (for example, hotplugging devices using igb_uio driver while having picked IOVA as VA mode on EAL initialization).

Implication

Some devices (hotplugged or otherwise) may not work due to incompatible IOVA mode being automatically picked by EAL.

Resolution/Workaround:

It is possible to force EAL to pick a particular IOVA mode by using the –iova-mode command-line parameter. If conflicting requirements are present (such as one device requiring IOVA as PA and one requiring IOVA as VA mode), there is no workaround.

Affected Environment/Platform:

Linux.

Driver/Module:

ALL.

38.38. Vhost multi-queue reconnection failed with QEMU version 4.2.0 to 5.1.0

Description

It’s a QEMU regression bug (bad commit: c6beefd674ff). QEMU only saves acked features for one vhost-net when vhost quits. When vhost reconnects to virtio-net/virtio-pmd in multi-queue situations, the features been set multiple times are not consistent. QEMU-5.2.0 fixes this issue in commit f66337bdbfda (“vhost-user: save features of multiqueues if chardev is closed”).

Implication

Vhost cannot reconnect back to virtio-net/virtio-pmd normally.

Resolution/Workaround:

It is possible to filter the incorrect acked features at vhost-user side.

Affected Environment/Platform:

ALL.

Driver/Module:

Virtual Device Poll Mode Driver (PMD).