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Re: [Xen-devel] [PATCH] xen: arm: remove /xen-core-devices node from dom0 dtb

On Fri, 2013-11-22 at 14:18 +0000, Julien Grall wrote:
> On 11/22/2013 01:47 PM, Ian Campbell wrote:
> > The intention of adding this node to contain the GIC, timer and memory nodes
> > (in 1c08d6004ea7) was to allow us to control the #address-cells and
> >
> > However in the case of the memory node the #*-cells are always taken from 
> > the
> > root node (see ePAPR 3.1, "the following nodes shall be present at the 
> > root...
> > memory node"). This caused breakage on the arndale platform.
> >
> > In addition it is not valid to just create sub-nodes like this. Unless they
> > declare themselves as a bus then they will not necessarily be enumerated
> > (although Linux currently does so in practice).
> >
> > Therefore:
> >   - Move the memory node back to the top level.
> >   - Insert the timer and gic nodes in the same location as in the host DTB,
> >     replacing the originals. Note that the nodes here may be marked as in 
> > use
> >     by Xen and therefore the check must be before we discard nodes used by 
> > Xen.
> If you insert the GIC and timer nodes at the same location you need to 
> make sure the use the right value. For instance it may happen to have 
> multiple GIC in the device tree.
> Actually, Xen skips all the GIC nodes and create just one. Here, you 
> replace all the possible GIC nodes by the same value (I'm not sure how 
> Linux will deal with that).

Damn, I forgot about this case. I'm not sure how relevant it is to us
today though -- do we support any such systems and/or would they be
likely to just work, I would expect not?

> For now, I think the best the solution is to check if we are the main 
> interrupt controller. If not, the function just need to return 0.

Means checking dt_interrupt_controller->phandle against the node in
hand, right?

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