Re: [U-Boot] [RFC] Kbuild support for ARM FIT images

Jason Kridner
2013-02-22T07:56:36Z

On Thu, Feb 21, 2013 at 9:22 PM, Jason Gunthorpe
<jgunthorpe@obsidianresearch.com> wrote:
> On Thu, Feb 21, 2013 at 06:19:05PM -0600, Rob Herring wrote:
>
>> The desired FPGA use case is DT updates after booting the kernel. This
>> has nothing to do with FIT images. And if the FPGA tools generate the
>> DTB, then it is certainly not tied to the kernel.
>
> Completely unrelated, but do you have any pointer for how to do this?
> Hot plugging a 'dtb fragment' into the kernel would be really handy..

This doesn't answer the full question on how FPGA tools generate DTB,
but it is a huge problem for BeagleBone add-on hardware that we have
some mechanism to dynamically load DT fragments. Pantelis posted some
work in that direction[1] and has continued development of his patches
and we've been using those extensively with BeagleBone kernel
development[2].

It would be great if the FPGA folks would get on-board in supporting
the dynamically loadable DT overlay fragments by reviewing and
supporting upstream acceptance of the code.

[1] http://lwn.net/Articles/531569/
[2] http://github.com/beagleboard/kernel/tree/3.8

>
> I'm thinking something like adding a tree below a PCI controller
> describing a PCI device and sub nodes, similar to what Thierry was
> doing for his Avionics. How would interrupt maps and phandles be
> managed across the main dtb and the 'hot plugged' dtb?
>
> Regards,
> Jason
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