6. Known Issues and Limitations
This section describes known issues with the DPDK software.
6.1. Unit Test for Link Bonding may fail at test_tlb_tx_burst()
Title |
Unit Test for Link Bonding may fail at test_tlb_tx_burst() |
Reference # |
IXA00390304 |
Description |
Unit tests will fail at test_tlb_tx_burst function with error for uneven distribution
of packets. |
Implication |
Unit test link_bonding_autotest will fail |
Resolution/ Workaround |
There is no workaround available. |
Affected Environment/ Platform |
Fedora 20 |
Driver/Module |
Link Bonding |
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) |
6.7. 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) |
6.14. Twinpond and Ironpond NICs do not report link status correctly
Title |
Twinpond and Ironpond NICs do not report link status correctly |
Reference # |
IXA00378800 |
Description |
Twin Pond/Iron Pond NICs do not bring the physical link down when shutting down the
port. |
Implication |
The link is reported as up even after issuing “shutdown” command unless the cable is
physically disconnected. |
Resolution/ Workaround |
None. |
Affected Environment/ Platform |
Twin Pond and Iron Pond NICs |
Driver/Module |
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) |
6.23. Cannot set link speed on Intel® 40G ethernet controller
Title |
Cannot set link speed on Intel® 40G ethernet controller |
Reference # |
IXA00386379 |
Description |
On Intel® 40G Ethernet Controller:
It cannot set the link to specific speed.
|
Implication |
The link speed cannot be changed forcedly, though it can be configured by
application. |
Resolution/ Workaround |
None |
Affected Environment/ Platform |
All |
Driver/Module |
Poll Mode Driver (PMD) |
6.24. Stopping the port does not down the link on Intel® 40G ethernet controller
Title |
Stopping the port does not down the link on Intel® 40G ethernet controller |
Reference # |
IXA00386380 |
Description |
On Intel® 40G Ethernet Controller:
Stopping the port does not really down the port link.
|
Implication |
The port link will be still up after stopping the port. |
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.
|
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 |