On Wed, Aug 19, 2009 at 1:37 PM, Avi Kivity<avi@xxxxxxxxxx> wrote: > > Well I'm not an Infiniband expert. But from what I understand VMM bypass > means avoiding the call to the VMM entirely by exposing hardware registers > directly to the guest. > It enables clients to talk directly to the hardware. Whether or not that involves registers would be model specific. But frequently the queues being written were in the client's memory, and only a "doorbell ring" involved actual device resources. But whatever the mechanism, it enables the client to provide buffer addresses directly to the hardware in a manner that cannot damage another client. The two key requirements are a) client cannot enable access to pages that it does not already have access to, and b) client can delegate that authority to the Adapter without needing to invoke OS or Hypervisor on a per message basis. Traditionally that meant that memory maps ("Regions") were created on the privileged path to enable fast/non-privileged references by the client. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html