[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-users] PCI Passthrough - Write-back to unknown field

Hi all!

I'm trying to passthrough a NI PCI-6025E card from Xen version 4.8.0 (Ubuntu 4.8.0-1ubuntu2.2) to HVM Windows 2000. The pass through itself is done accordingly to documentation. Guest OS determines the card as unknown PCI device. Installing the driver allows to recognize device as Data Acquisition Device / PCI-6028E in Windows Device Manager and in NI software. However, running tests from NI test panels fails with "The device is not responding to the selected base address" (in fact it seems to be "overFlowError" with detailed description "Because of system and/or bus-bandwidth limitations, the driver could not read data from the device fast enough to keep up with the device throughput; the onboard device memory reported an overflow error"). QEMU log file contains an error "Write-back to unknown field 0x08 (partially) inhibited (0x000000), If the device doesn't work, try enabling permissive mode (unsafe) and if it helps report the problem to xen-devel". Adding permissive=1 to the pci section of the domain configuration file makes the error from the QEMU log disappear, but the card itself still can not pass the test in the guest system.

I don't have a deep knowledge in device passthroughing, but as far as I understand passthrough means that everything from the virtual machine is just passed to the real one. This leads to a conclusion that the main trouble is to pass the device to the guest, once device is seen by the guest everything should be fine. Am I understanding something wrong?

The device shows in xl pci-assignable-list in Dom0
Relevant part from xl dmesg

(XEN) Initing memory sharing.
(XEN) Intel VT-d iommu 1 supported page sizes: 4kB.
(XEN) Intel VT-d iommu 0 supported page sizes: 4kB.
(XEN) Intel VT-d iommu 2 supported page sizes: 4kB.
(XEN) Intel VT-d Snoop Control not enabled.
(XEN) Intel VT-d Dom0 DMA Passthrough not enabled.
(XEN) Intel VT-d Queued Invalidation not enabled.
(XEN) Intel VT-d Interrupt Remapping not enabled.
(XEN) Intel VT-d Posted Interrupt not enabled.
(XEN) Intel VT-d Shared EPT tables not enabled.
(XEN) I/O virtualisation enabled
(XEN)  - Dom0 mode: Relaxed
(XEN) Interrupt remapping disabled

Can you help me to solve/debug this issue, please? Any ideas, guesses or suggestions are welcome.

Thank you in advance


Xen-users mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.