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Re: [Xen-devel] [RFC 00/24] Allow Xen to boot with a raw Device Tree

On 16 August 2013 22:05, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> Hi,
> This is the first patch series to allow Xen to boot with a raw device tree, ie
> without any specific modification for Xen.
> Few months ago, the patch series "Support multiple ARM platform in XEN", has
> added a tree structure to handle easier the device tree. Each node can carry
> metadata to specify if the node can be pass-through to Dom0. Therefore, this
> patch series take advantage of the "new" Device Tree API and get a rid of
> the FDT API that is currently used to build Dom0 dts and in some drivers.
> There is few items that was not added in this series:
>     * Set the correct number of CPUs for Dom0 by editing CPUs node
>     * Remove and create the GIC node
>     * Remove and create the timer node
> I hope to add support for previous items in the next patch series.
> At the beginning of the mail, I a bit lied about Xen is able to raw DTS :).
> The latter, still need to carry Xen and Linux command line until U-Boot/Grub
> will support multiboot2 protocol.
> I have noticed that U-boot has some fdt commands to change on the fly the 
> device
> tree. I think we can use this solution as a workaround for the beginning.
> I will send an email later to explain the procedure.

As promised, I wrote a small U-boot to remove all remaining changes in
the Device Tree (modules and xen/dom0 bootargs). This script requires
Andre's patch (http://osdir.com/ml/general/2013-05/msg68353.html).


The script creates:
   - Xen and Dom0 bootargs
   - the modules node with linux address correctly set up

I think, this script can be used as a workaround to avoid manual
Device Tree modification until U-boot/Grub will support correctly
multiboot. If people are insterested by this script, I can create a
wiki page with all the instructions.


Julien Grall

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