[dpdk-dev] [Question] How pmd virtio works without UIO?

[Yuanhan Liu]

On Tue, Dec 22, 2015 at 11:50:41AM +0800, Peter Xu wrote:
> Hi,
> 
> I got a question related to how virtio pmd driver work without
> UIO layer.
> 
> I see that in virtio PMD driver, DPDK will first try to init the
> device using UIO interfaces. If it fails, it will try to init by
> manipulating IO ports directly (see virtio_resource_init()).
> 
> For the ioport case, is it okay to do it like this? E.g., in
> eth_virtio_dev_init(), we are resetting the virtio device, however,
> this device should still be owned by virtio-pci driver in the
> kernel.
> 
> How is that working? Did I miss anything?

That's for configuration part: as far as we can read/write the right
PCI port, virtio pmd configuration will work. Note that on this case,
uio just provides another way to tell you where the port is.

	--yliu