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RE: [Xen-devel] problem with netfront.c

To: "Ling, Xiaofeng" <xiaofeng.ling@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] problem with netfront.c
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Sun, 3 Apr 2005 14:33:15 +0100
Delivery-date: Sun, 03 Apr 2005 13:33:29 +0000
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Thread-index: AcU39PebD2/thBv+Rdms3itvtFiuwQAPExGgAAL3ilAAA/XnwA==
Thread-topic: [Xen-devel] problem with netfront.c
> Yes, but does it still need hypervisor to modify the 
> phys_to_machine table?
> I just hope to save some page faults or tlb flush vmexit to 
> get high performance and also have less modification to the 
> original netfront.c. So still only one multicall needed each 
> time when gets a net event.

The netfront/backdriver driver needs to be switched over to using the
grant tables interface. 

Chris Clark has already checked in the grant tables implementation, but
no-one has got around to updating netfront/back to use it. There are
patches to switch blkfront/back over to use grant tables, which will be
checked in soon, but since the blk driver use the foreign access rather
than the page transfer mechanism its probably not too much help. 

Using grant tables, the front end doesn't need to know about machine
addresses, and the whole thing ends up rather cleaner, particulary for
domains running with virtualized VMs.

I've attached a document from Chris that gives a rough description of
the grant table interface.

Best,
Ian

Attachment: grant-tables.txt
Description: grant-tables.txt

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