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Re: [Xen-devel] SR-IOV problems - HVM cannot access network

On Wed, 2 Mar 2011, Stefano Stabellini wrote:

> On Wed, 2 Mar 2011, David White wrote:
> > Thanks for your help so far.
> >
> > Ubuntu Maverick is only running in the guest HVM domains.
> >
> > I have two boards I am testing with, both with Intel 5520 chipset.  I'm 
> > using
> > two 82576 nics from two different vendors, one attached to either board.  
> > Both
> > systems have AMI bios.  One system (call it systemA) has bios options for 
> > both
> > VT-d and SR-IOV, and both are enabled, as is I/OAT.  The other system 
> > (systemB)
> > has bios options for VT-d and "Coherency support" (which seemed to help me
> > enumerate the VFs), and both are enabled (no mention of I/OAT).
> >
> > SystemA runs Debian Squeeze and the xen kernel, vmm and tools from that 
> > distro.
> > SystemB runs Fedora14 with the well-known "jeremy" kernel
> > (http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=shortlog;h=xen/stable-2.6.32.x),
> > and xen-4.0.1 hypervisor built from source (unaltered).
> >
> > Both systems are experiencing the same behavior.
> >
> > attached are dom0 and hvm ethregs output for the VF using '-o -m'
> > flags.  This one was taken from the Debian host ("systemA")
> could you please try adding
> acpi=0
> in your VM config file?

Hm, ok that seemed to do the trick, as far as getting the VFs up on the network.

Is this by design or is it a workaround? Must I sacrifice acpi in my guest to
enable sr-iov?  Does this come with a cost to I/O performance, since the guest
isn't using MSI?


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