Re: [Qemu-devel] Using virtio-net and vhost_net on an ARM machine using qemu-system-arm & KVM

[Peter Maydell]

On 9 January 2014 12:25, Barak Wasserstrom <address@hidden> wrote:
> Hi,
> I would like to utilize virtio-net and vhost_net on an ARM Cortex A15
> machine using qemu-system-arm & KVM.
> I have few questions:
> 1. Do i need to build qemu-system-arm myself, or apt-get install it? When i
> apt-get install it i get "KVM not supported for this target. "kvm"
> accelerator does not exist. No accelerator found!".

This sounds like either:
 (1) you're using too old a version of QEMU and need a newer one
 (2) you configured QEMU without KVM support

Provided you have QEMU 1.6 or later it shouldn't matter whose
version you're using.

> 2. Do i need to execute qemu-system-arm directly or through virsh? Does it
> matter?

I know nothing about virsh but I don't expect it matters. It's
probably easier to get things working by running qemu-system-arm
directly first, before you try to work out how to get virsh to start
qemu with the correct arguments.

> 3. Must i use a machine that supports PCI controller or not? And if so,
> which machine supports it? I saw that 'virt' and 'vexpress' don't support
> it.

No. For KVM to work you need to use an A15 guest CPU; there
are no A15 boards in QEMU which have a PCI controller. So
instead you have to use the vexpress-a15 or virt machine's
virtio-mmio support. Note that generally the command line syntax
for this is different from that used by x86: you need to create
virtio-*-device devices, not virtio-* or virtio-*-pci devices, and you
can't rely on shorthands like if=virtio. So for instance for a block
device you need
  -drive if=none,file=root,id=foo -device virtio-blk-device,drive=foo

thanks
-- PMM