Hi,
I'm having an issue with a SRIOV device under dom0. I'm running Ubuntu 15.04
with Xen 4.5. There is also Debian Wheezy HVM guest present. The device is
creating 32 virtual functions. If a VF is connected to the guest, it all works fine,
but a VF does not work in dom0. Mode of operation is simple. Two rings
buffers are allocated for DMA, TX and RX. Data is placed in TX buffer and tail is
written to a register. Card then reads data and sets head to match tail. A short
while later it writes data to RX buffer and sets tail. But when RX buffer is
inspected, it comes out empty. Nothing has been written to it.
On the guest, there is data in this buffer which is then read by us.
I tried to debug this for a while, but nothing prints an obvious error message
that would be useful. I tried iommu command line parameters for Xen like
dom0-passthrough, dom0-strict, verbose, debug and nothing helped. I ran
out of ideas really how to poke this issue. I have no access to card's internals
so I cannot check what's doing. Tests were also done on proper Xenserver 6.5
and the behaviour is the same. For Qemu+KVM it works fine.
Kuba
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