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Re: [Xen-devel] RFC -- virtualisable NIC support in Xen

To: Caitlin Bestler <caitlinb@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] RFC -- virtualisable NIC support in Xen
From: Greg Law <glaw@xxxxxxxxxxxxxx>
Date: Fri, 22 Sep 2006 12:04:38 +0100
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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 Law               glaw@xxxxxxxxxxxxxx              +44 1223 518 040

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