RE: [Xen-devel] address mapping between domains

[Rik van Riel <riel@xxxxxxxxxx>]

On Tue, 8 Mar 2005, Ian Pratt wrote:

> At the expense of protection, yes.

Protection against mistakes, which can be mitigated by having the
full physical memory map at a different address from where the
kernel usually accesses its memory.

I suspect we won't have to try protecting against a malicious
domain 0 ;)

> 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.

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan


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