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xen-devel
RE: [Xen-devel] [RFC][PATCH 0/6] HVM PCI Passthrough (non-IOMMU)
Hi Jhon,
Thanks for testing out our patches!
My comments below.
> -----Original Message-----
> From: John Byrne [mailto:john.l.byrne@xxxxxx]
> Sent: Friday, June 08, 2007 5:53 AM
> To: Guy Zana
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [RFC][PATCH 0/6] HVM PCI Passthrough
> (non-IOMMU)
>
>
> Guy,
>
> I tried your patches with a bnx2 NIC on SLES10 and they didn't work.
>
> The first reason was that you mask off the capabilities bit
> in the PCI status. If I got rid of this, I could at least get
> the NIC to configure, but it didn't work and the dropped
> packets looked to be random garbage, so I don't think it was
> talking to the device properly. (But I understand almost
> nothing about PCI device configuration, so I don't know what
> to look for.)
>
The released patches are considered to be "developmental", there are still work
needed to be done (not too much though :) ) in order to make it usable for
everyone. Are you sure you mapped the right IRQ? Please post the qemu-dm log
file / xm dmesg. The capabilities bits are masked-off so we won't need to
handle MSIs yet and power management (ACPI) related stuff, that could be quite
a pain when trying to do pass-through for integrated devices.
Another thing,
Does this NIC card has an expansion ROM?
> I haven't noticed the merge tree springing into existence
> into on xenbits, so is there any progress on making into a
> real feature? It sounds like most of the work needs to be
> done between you and Intel, but I could certainly help with testing.
>
That would be great!
I think that both patches (ours' and Intel's) need some more work before we can
start merging.
Neocleus already merged some parts from the Intel patches (mmio & pio
handling). We are also aiming for 64bits (x86) support on the next release.
> One thing I am interested in is, with the 1:1 mapping, could
> we disable the VT page-fault handling? I've found that the
> page-fault overhead for VT is horrible and would probably
> affect fork-exec benchmarks significantly.
Cool idea! Our CTO thought about it as well :)
It's kind of hard not to use the VT page-fault handler at all, there are some
issues with memory protection (security), and memory-remapping that we would
want to do in the future (In order to support bios & expansion ROM
duplication). I agree that you can make it faster though! it may require some
drastic changes in the hypervisor.
Thanks,
Guy.
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