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Date: Sat, 11 Jun 2011 16:53:04 -0400
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From: Ryan Stone <rysto32@gmail.com>
To: Luigi Rizzo <rizzo@iet.unipi.it>
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Cc: freebsd-net@freebsd.org, "K. Macy" <kmacy@freebsd.org>
Subject: Re: FreeBSD I/OAT (QuickData now?) driver
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On Sat, Jun 11, 2011 at 2:55 PM, Luigi Rizzo <rizzo@iet.unipi.it> wrote:
> I am also looking at other options, eg. a "mixed" mode where
> certain packets (e.g. depending on the MAC address) retain
> the usual path, whereas others stay in the netmap ring.
> Of course when you need to replicate packets (multicast/broadcast)
> you have to pay the price somewhere -- even the 85299 (intel 10G
> controller) can do some replication in hardware but it
> takes some precious PCIe and memory bus cycles to do so.

I've independently implemented something very similar to this at
$(WORK) for the ixgbe driver and I intend on cleaning up the patch
this summer and submitting it to jfv.  My approach is more general
than what you're describing here: my ixgbe driver has the capability
to present multiple virtual interfaces to the rest of the system that
share a single virtual interface.  The main use case I was envisioning
for this was with vnet and/or jails, but it sounds like it would mesh
very well with netmap.  You can create one virtual interface for
netmap and one for the stack, and the driver and hardware take care of
the multiplexing transparently.