Re: [dpdk-dev] Having troubles binding an SR-IOV VF to uio_pci_generic on Amazon instance

[Vladislav Zolotarov <vladz@cloudius-systems.com>]

On Sep 27, 2015 12:43 PM, "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> On Sun, Sep 27, 2015 at 10:05:11AM +0300, Vlad Zolotarov wrote:
> > Hi,
> > I was trying to use uio_pci_generic with Intel's 10G SR-IOV devices on
> > Amazon EC2 instances with Enhanced Networking enabled.
> > The idea is to create a DPDK environment that doesn't require compiling
> > kernel modules (igb_uio).
> > However I was surprised to discover that uio_pci_generic refuses to work
> > with EN device on AWS:
> >
> > $ lspci
> > 00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma]
(rev 02)
> > 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton
II]
> > 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE
[Natoma/Triton II]
> > 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 01)
> > 00:02.0 VGA compatible controller: Cirrus Logic GD 5446
> > 00:03.0 Ethernet controller: Intel Corporation 82599 Ethernet
Controller Virtual Function (rev 01)
> > 00:04.0 Ethernet controller: Intel Corporation 82599 Ethernet
Controller Virtual Function (rev 01)
> > 00:1f.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device
(rev 01)
> >
> > $ sudo ./dpdk/tools/dpdk_nic_bind.py -b uio_pci_generic 00:04.0
> > Error: bind failed for 0000:00:04.0 - Cannot bind to driver
uio_pci_generic
>
> > $dmesg
> >
> > --> snip <---
> > [  816.655575] uio_pci_generic 0000:00:04.0: No IRQ assigned to device:
no support for interrupts?
> >
> > $ sudo lspci -s 00:04.0 -vvv
> > 00:04.0 Ethernet controller: Intel Corporation 82599 Ethernet
Controller Virtual Function (rev 01)
> >       Physical Slot: 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-
> >       Region 0: Memory at f3008000 (64-bit, prefetchable) [size=16K]
> >       Region 3: Memory at f300c000 (64-bit, prefetchable) [size=16K]
> >       Capabilities: [70] MSI-X: Enable- Count=3 Masked-
> >               Vector table: BAR=3 offset=00000000
> >               PBA: BAR=3 offset=00002000
> >       Kernel modules: ixgbevf
> >
> > So, as we may see the PCI device doesn't have an INTX interrupt line
> > assigned indeed. It has an MSI-X capability however.
> > Looking at the uio_pci_generic code it seems to require the INTX:
> >
> > uio_pci_generic.c: line 74: probe():
> >
> >       if (!pdev->irq) {
> >               dev_warn(&pdev->dev, "No IRQ assigned to device: "
> >                        "no support for interrupts?\n");
> >               pci_disable_device(pdev);
> >               return -ENODEV;
> >       }
> >
> > Is it a known limitation? Michael, could u, pls., comment on this?
> >
> > thanks,
> > vlad
>
> This is expected. uio_pci_generic forwards INT#x interrupts from device
> to userspace, but VF devices never assert INT#x.
>
> So it doesn't seem to make any sense to bind uio_pci_generic there.
>
> I think that DPDK should be fixed to not require uio_pci_generic
> for VF devices (or any devices without INT#x).
>
> If DPDK requires a place-holder driver, the pci-stub driver should
> do this adequately. See ./drivers/pci/pci-stub.c

Thank for clarification, Michael. I'll take a look.

>
> --
> MST