Re: [PATCH] Bugfix for handling of shadow doorbell buffer.

[Christoph Hellwig]

On Tue, Aug 14, 2018 at 06:35:16PM -0700, Michal Wnukowski wrote:
> 
> The other side in this case is not actual controller hardware, but 
> virtual one (the regular hardware should rely on normal MMIO 
> doorbells).

There could very much be real hardware there.  We've made it clear
in the spec that while a typical use case is a virtualized controller
there is nothing peventing hardware implementations.  There have
been previous hardware prototypes to use very similar tricks, e.g.:

https://www.usenix.org/node/179878