RE: [Xen-devel] address mapping between domains

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> > With sane DMA-capable hardware the driver domain never 
> needs to actually
> > map the page into its address space anyhow. However, the grant table
> > stuff will still be required to enable us to configure the IO MMU
> > appropriately to allow the DMA (we expect to see such h/w 
> support become
> > commonplace). 
> 
> True for some kinds of IO.  Network IO needs sorting through
> packets, so no direct DMA will be done.

The headers of network packets are sent out-of-band so that mapping of
the main payload is only required if you have some very fancy iptables
rules that do deep inspection.

I don't believe there's a significant overhead to the protection
provided by grant tables, and they go some way to keeping the security
folks happy.

Anyhow, we can benchmark it in a couple of days...

Ian


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_ide95&alloc_id396&op=click
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel