Re: [Xen-devel] [PATCH V2 24/33] xen/arm: WORKAROUND 1:1 memory mapping for dom0

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-05-08 at 03:33 +0100, Julien Grall wrote:
> Currently xen doesn't implement SYS MMU. When a device will talk with dom0
> with DMA request the domain will use GFN instead of MFN.
> For instance on the arndale board, without this patch the network doesn't
> work.
> 
> The 1:1 mapping is a workaround and MUST be remove as soon as a SYS MMU is
> implemented in XEN.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

(Somewhat reluctantly) Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

I consider this to be a temporary workaround and at some point (possibly
even as soon as 4.4) I intend to push for its removal, even if this
breaks some platforms which have not by then implemented SYS MMU support
for whatever reason.

Vendors who care about support for their platform under Xen need to sort
out SYS MMU support for them sooner rather than later (which probably
means patches, but documentation would be at least a tolerable
alternative).

> + * Usefull on platform where System MMU is not yet implemented

"Useful"

Ian.


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