ConnectX-4 Lx Virtual Function has LnkSta: Speed unknown (downgraded), Width x0 (downgraded)

I have to create 3 VFs devices using SRIOV feature from MLNX by echo 3 > sriov_numvfs
This is VFs devices:
0009:01:00.2 Ethernet controller: Mellanox Technologies MT27710 Family [ConnectX-4 Lx Virtual Function]

But when I check LnkSta, I get “Speed unknown (downgraded), Width x0 (downgraded)”. I would like ask that why Speed unknown and Width x0

# lspci -s 0009:01:00.2 -vvv
0009:01:00.2 Ethernet controller: Mellanox Technologies MT27710 Family [ConnectX-4 Lx Virtual Function]
        Subsystem: Mellanox Technologies Device 0057
        Physical Slot: 1-4
        Control: I/O- Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0
        NUMA node: 1
        IOMMU group: 65
        Region 0: Memory at 640004000000 (64-bit, prefetchable) [virtual] [size=1M]
        Capabilities: [60] Express (v2) Endpoint, MSI 00
                DevCap: MaxPayload 512 bytes, PhantFunc 0, Latency L0s unlimited, L1 unlimited
                        ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset+ SlotPowerLimit 0.000W
                DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
                        RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop- FLReset-
                        MaxPayload 128 bytes, MaxReadReq 128 bytes
                DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
                LnkCap: Port #0, Speed 8GT/s, Width x8, ASPM not supported
                        ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
                LnkCtl: ASPM Disabled; RCB 64 bytes, Disabled- CommClk-
                        ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
                LnkSta: Speed unknown (downgraded), Width x0 (downgraded)
                        TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
                DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR-
                         10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt- EETLPPrefix-
                         EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
                         FRS- TPHComp- ExtTPHComp-
                         AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- OBFF Disabled,
                         AtomicOpsCtl: ReqEn-
                LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
                         EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
                         Retimer- 2Retimers- CrosslinkRes: unsupported
        Capabilities: [9c] MSI-X: Enable+ Count=12 Masked-
                Vector table: BAR=0 offset=00002000
                PBA: BAR=0 offset=00003000
        Kernel driver in use: mlx5_core
        Kernel modules: mlx5_core

Hello @OKOK98,

Thank you for posting your query on our community. This is the expected result for VFs as they have limited PCIe capabilities compared to PFs. They typically use a subset of the PCIe lanes and resources allocated by the PF.


It means that Vfs have link Speed unknown (downgraded), Width x0 (downgraded). Is that right??

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