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

[Peter Xu]

On Wed, Dec 23, 2015 at 10:09:49AM +0800, Yuanhan Liu wrote:
> Why can't we simply quit at pci_scan_one, once finding that it's not
> bond to uio (or similar stuff)? That would be generic enough, that we
> don't have to do similar checks for each new pmd driver.
> 
> Or, am I missing something?

It seems that ioport way to play with virtio devices do not require
any PCI wrapper layer like UIO/VFIO? Please check
virtio_resource_init().

> 
> 
> > I guess there might be two problems? Which are:
> > 
> > 1. How user avoid DPDK taking over virtio devices that they do not
> >    want for IO (chooses which device to use)
> 
> Isn't that what's the 'binding/unbinding' for?
> 
> > 2. Driver conflict between virtio PMD in DPDK, and virtio-pci in
> >    kernel (happens on every virtio device that DPDK uses)
> 
> If you unbinded the kernel driver first, which is the suggested (or
> must?) way to use DPDK, that will not happen.

Yes, maybe we should unbind it first. I am just not sure what will
happen if not.

Peter