Re: [Qemu-devel] Network Passthrough configuration!

[GaoYi]

  So is my command line to start the guest OK? The command line is as:

        qemu-img -boot c -hda readhat.img -device pci-assign,host=XX:00.0

  Why doesn't the network work?

Yi

2012/8/25 Stefan Hajnoczi <address@hidden>

On Sat, Aug 25, 2012 at 5:35 AM, GaoYi <address@hidden> wrote:
> Hi all,
>
>    I am trying to implement pci passthrough for network card according to
> this guideline:
> http://www.linux-kvm.org/page/How_to_assign_devices_with_VT-d_in_KVM.
>    The configuration steps were all ok. However, when I started the guest
> by:
>              qemu-img -boot c -hda readhat.img -device
> pci-assign,host=XX:00.0,
>  the network of the guest failed. And the host shell reported: cannot read
> from host /sys/bus/pci/devices/0000.XXX/rom. I am very sure the PCI is
> rightly selected from commands like "lspci -n". So what is the full command
> line to start a guest with network being OK?

I guess you hit this error message:

pci-assign: Cannot read from host %s.  Device option ROM contents are
probably invalid (check dmesg).  Skip option ROM probe with rombar=0
or load from file with romfile=

This is a warning that the option ROM could not be loaded.  It's not a
fatal error and probably just means you cannot use the PCI NIC's
network boot ROM (PXE) inside the guest.  But the NIC should still
work once your guest OS is booted.

I don't know if there are other implications but it seems to be a
non-fatal warning.

>    Besides, how to configure the libvirt XML file so that passthrough can
> work well from Virsh tools?

Try this guide for PCI device assignment with libvirt:
https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/chap-Virtualization_Host_Configuration_and_Guest_Installation_Guide-PCI_Assignment.html

Stefan