[U-Boot] [PATCH v3 00/12] cmd: fdt: Add device tree overlays support

[Maxime Ripard]

Hi David,

On Mon, Jun 27, 2016 at 01:37:19AM +1000, David Gibson wrote:
> On Fri, Jun 24, 2016 at 04:27:45PM +0200, Maxime Ripard wrote:
> > Hi,
> > 
> > The device tree overlays are a great solution to the issue raised by
> > the bunch expandable boards we find everywhere these days, like the
> > Beaglebone, Raspberry Pi or CHIP.
> > 
> > However, most of the time, the overlays are applied through a
> > mechanism involving the firmware request interface in Linux, that is
> > only fully functional once the userspace has been mounted and is
> > running.
> > 
> > Some expansion boards might need to be enabled before that, because
> > they simply need to patch the DT early on, or need to be initialized
> > early in order to be fully functional, or because they provide access
> > to the root filesystem.
> > 
> > In these cases, having the bootloader applying the overlay before
> > Linux starts seems like the easiest solution.
> > 
> > This implementation doesn't provide all the Linux fancyness though,
> > there's no transactional application, which means that if the overlay
> > cannot be applied for a reason while you're still halfway through the
> > application, you're probably screwed. It also cannot remove an
> > overlay, but I don't think that it is currently a use-case.
> > 
> > There's still a bunch of work to extend the libfdt unit tests to test
> > the new functions introduced, but these patches will be submitted
> > in a near future.
> 
> Are you planning to send a new version of (the relevant portions of)
> these against upstream libfdt?

Of course, I just only have to work on the test cases now.

Simon wanted to merge this in U-Boot for the next merge window, and
then sync with libfdt when it would be merged, hence why I posted it
first.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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