[Xen-devel] [Question] Do we need to support devices that do not strictly follow the PCI-e specification?

["Shan, Haitao" <haitao.shan@xxxxxxxxx>]

Hi, Keir,

 

When debugging recently, I found some devices that did not follow the PCI-e specification strictly. Below is an example.

 

From PCI-e spec, PCI-e capability occupies 0x3c bytes of configuration space. Unimplemented registers are reserved and hardwired to zero. But for device listed below, PCI-e capability should begin at 0x4C and end at 0x88. But this device implements MSI, VPD, MSI-X capabilities in the reserved spaces. Current code can not handle this.

 

My question is do we need to add hacks to handle such kinds of devices?

 

Here is the output of lspci:

 

03:00.0 Fibre Channel: QLogic Corp. ISP2432-based 4Gb Fibre Channel to PCI Express HBA (rev 03)

        Subsystem: QLogic Corp. Unknown device 0138

        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-

        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-

        Interrupt: pin A routed to IRQ 18

        Region 0: I/O ports at 3000 [disabled] [size=256]

        Region 1: Memory at d8500000 (64-bit, non-prefetchable) [disabled] [size=16K]

        [virtual] Expansion ROM at d8800000 [disabled] [size=256K]

        Capabilities: [44] Power Management version 2

                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)

                Status: D0 PME-Enable- DSel=0 DScale=0 PME-

        Capabilities: [4c] Express Endpoint IRQ 0

                Device: Supported: MaxPayload 1024 bytes, PhantFunc 0, ExtTag-

                Device: Latency L0s <4us, L1 <1us

                Device: AtnBtn+ AtnInd+ PwrInd+

                Device: Errors: Correctable- Non-Fatal- Fatal- Unsupported-

                Device: RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+

                Device: MaxPayload 128 bytes, MaxReadReq 512 bytes

                Link: Supported Speed 2.5Gb/s, Width x4, ASPM L0s, Port 0

                Link: Latency L0s <4us, L1 unlimited

                Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-

                Link: Speed 2.5Gb/s, Width x4

        Capabilities: [64] Message Signalled Interrupts: 64bit+ Queue=0/4 Enable-

                Address: 00000000fee00000  Data: 40b9

        Capabilities: [74] Vital Product Data

        Capabilities: [7c] MSI-X: Enable- Mask- TabSize=16

                Vector table: BAR=1 offset=00002000

                PBA: BAR=1 offset=00003000

00: 77 10 32 24 00 00 10 00 03 00 04 0c 08 00 80 00

10: 01 30 00 00 04 00 50 d8 00 00 00 00 00 00 00 00

20: 00 00 00 00 00 00 00 00 00 00 00 00 77 10 38 01

30: 00 00 00 00 44 00 00 00 00 00 00 00 0a 01 00 00

40: 00 00 00 00 01 4c 02 00 00 00 00 00 10 64 01 00

50: 83 71 00 00 10 28 00 00 41 e4 03 00 00 00 41 10

60: 00 00 00 00 05 74 88 00 00 00 e0 fe 00 00 00 00

70: b9 40 00 00 03 7c 00 80 82 2e 00 50 11 00 0f 00

80: 01 20 00 00 01 30 00 00 00 00 00 00 00 00 00 00

90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

 

Best Regards

Shan Haitao

 

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