From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frank Rowand <frowand.list-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: Re: Virtualization difficulty -- phandles
Date: Mon, 24 Jul 2017 09:27:44 -0700
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To: Cyril Novikov <cnovikov-wte42BQEg7M@public.gmane.org>, devicetree-spec-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

Hi Cyril,

On 07/11/17 23:15, Cyril Novikov wrote:
> Hi, all!
> 
> The product that I work on supports physical device assignment (aka
> "pass-through") to virtual machines, which means we need to take
> portions of the physical FDT and include them in the guest FDT. This
> needs to happen automatically in software.

Is this for Linux, or some other OS?

If Linux, do you get the FDT from /sys/firmware/fdt or some other
method?

-Frank

> The problem is phandles, because we cannot identify them in the blob
> and therefore can't find any dependent devices/nodes that also need
> to be included in the guest FDT. So the process cannot be fully
> automated. We can't even advise the user what other devices should be
> assigned to the VM. The hypervisor runs or bare metal, so having to
> parse the source DTS files for this is very inconvenient.
> 
> Would it be possible to add metadata properties to the binary FDT
> format, which would identify other property cells that are in fact
> phandles? It could be a per-node property or a single root node
> property, up to you guys. DTC would then automatically generate the
> metadata property along with the phandle property when compiling the
> DTS.
> 
> -- Cyril
> 
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