[Xen-devel] About passing through USB devices in HVM domain

["陈诚" <concretechen@xxxxxxxxx>]

HI,
    We are currently trying to pass through the USB controller (OHCI)
using 1-to-1 mapping domain (mainly based on the Neo-1-to-1 patch) on
a Non-VT-d machine. If we do not plug in any devices, the HVM works
fine, but as long as we plug in one USB device, the HVM domain
crashes.
    From the serial output we find that interrupts keep firing at the
IRQ line that was passed through. The Neo-1-to-1 patch uses a so
called CPA (change polarity algorithm) to handle interrupt pass
through, we are not very clear about this idea and even why it should
be done. Should any body explain it to us, that will be very helpful.
    We are also trying to pass through an IEEE 1394 OHCI Controller,
under FC6 HVM domain, it keeps on firing interrupts after the boot
process goes to udev step, which crashes the system. It is even worse
under WinXP, it crashes the system and makes permanent damage to the
QEMU disk image, we have know idea why this happens.
    By the way, we are using an AMD processor with SVM support.
    Thank you.

Cheers

ConcreteChen@xxxxxxxxx

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