From mboxrd@z Thu Jan  1 00:00:00 1970
From: Greg Law <glaw@solarflare.com>
Subject: Re: RFC -- virtualisable NIC support in Xen
Date: Fri, 22 Sep 2006 12:04:38 +0100
Message-ID: <4513C346.6070209@solarflare.com>
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To: Caitlin Bestler <caitlinb@broadcom.com>
Cc: xen@solarflare.com, xen-devel@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

Caitlin Bestler wrote:
> When the App/DomU posts a buffer (for TX or RX),
> what address does it use, and how does the hardware
> understand it?

It uses a "buffer address".  This is essentially an index into a 
"buffer-table" which is stored on the NIC.  This table is used to lookup 
physical addresses that the NIC will DMA to/from.

The buffer-table is programmed from Dom0.

The buffer-table is effectively our IOMMU/page-tables.

Hope this helps,

Greg

-- 
Greg Law               glaw@solarflare.com              +44 1223 518 040