Support for configurable PCIe endpoint

[Christoph Hellwig]

On Wed, Aug 03, 2016 at 06:03:54PM +0200, Arnd Bergmann wrote:
> drivers/ntb seems like a reasonable start, while an alternative
> approach that we have discussed in the past would be based on top
> of virtio, so we could use the existing front-end drivers (net, block,
> v9fs, console, ...).

I don't really think either is a good aproach for the lowest level
interface.  To be useful the EP driver needs to be able to implement
any (reasonable) thing a PCIe device could do.  Both NTB and virtio
can sit on top of that, though.