[dpdk-dev] [PATCH 2/2] uio: new driver to support PCI MSI-X

[Stephen Hemminger]

On Thu, 1 Oct 2015 16:40:10 -0700
Alexander Duyck <alexander.duyck at gmail.com> wrote:

> Do you really need to map IORESOURCE bars?  Most drivers I can think of 
> don't use IO BARs anymore.  Maybe we could look at just dropping the 
> code and adding it back later if we have a use case that absolutely 
> needs it.
Mapping is not strictly necessary, but for virtio it acts a way to communicate
the regions.

> Also how many devices actually need resources beyond BAR 0?  I'm just 
> curious as I know BAR 2 on many of the Intel devices is the register 
> space related to MSI-X so now we have both the PCIe subsystem and user 
> space with access to this region.

VMXNet3 needs 2 bars. Most use only one.