Re: [Xen-devel] [PATCH v4 5/8] xen/arm: assign devices to boot domains

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 9/24/19 5:52 PM, Stefano Stabellini wrote:
> On Wed, 11 Sep 2019, Julien Grall wrote:
> > It also raises the question what should we do if the size passed in not
> > page-aligned? Shall we just blindly round up/down? Should we warn?
> >
> > This was not important for dom0, but is potentially critical for domU as you
> > may happen to inadvertently to export more than you hope to a guest.
> A warning or even a panic would be OK because it is a static misconfiguration.
Yes and no, there are platforms where devices are sharing the same pages 
(see the UART on Sunxi SoC for instance). So this is a valid 
configuration, but we don't support it.
The problem does not arise for domU created by the toolstack because we 
request a frame. Note that I would not want to use a frame for Dom0less 
assignment as I think this is buggy.
Anyway, I would rather not add a panic in this code and let the upper 
layer deciding what to do.
Cheers,

--
Julien Grall

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