ACPI vs DT at runtime

[Pantelis Antoniou]

Hi

On Nov 22, 2013, at 12:43 PM, Catalin Marinas wrote:

> On 21 November 2013 20:47, Grant Likely <grant.likely at secretlab.ca> wrote:
>> On Thu, 21 Nov 2013 19:21:36 +0000, Russell King - ARM Linux <linux at arm.linux.org.uk> wrote:
>>> On Wed, Nov 20, 2013 at 07:40:57AM +0100, Richard Cochran wrote:
>>>> Now, I never saw any proclamation or discussion about "DT is in flux"
>>>> on the arm list. If I had, I surely would have complained, and loudly.
>>>> AFAICT, this decision was made in rather private circles, but you talk
>>>> as if this was abundantly clear. *It was not.*
>>> 
>>> DT has been discussed several times over this year alone, which
>>> included discussions about the stability of bindings.  Various
>>> people in those threads (including myself) have put their views
>>> forward.
>>> 
>>> My position has been that if an interface ends up being published in a
>>> -final kernel, then it is part of the ABI, because a -final kernel is
>>> an end-product.  It's a final release which says "we've done the
>>> development, it's finished for users use."  If it's not then it shouldn't
>>> be in a -final kernel, or if it has to be there for development purposes,
>>> it needs to be hidden behind a "this is in development" label.
> 
> +1
> 
>>> I've said that several times in the DT discussions and I believe
>>> basically been ignored.  Frankly, I've said my bit and I've given up
>>> caring.
>> 
>> Umm. Not sure why you feel ignored. We're absolutely going for stability
>> now.
> 
> What I was hoping for is a better way to enforce this by taking the
> dts files out of the kernel. I think that's the point where the
> bindings can become ABI. In the meantime we rely on contributors and
> reviewers making sure backwards compatibility is preserved. But I
> guess we'll eventually get there.
> 

As one that's going to be dealing with this, please don't take the DTS
files from the kernel.

If you do this, I can guarantee that within a year almost no ARM board using DT
will boot a mainline kernel.

The reason is that vendors have enough trouble (and failing) tracking a single
tree, adding yet another will just end to the vendor trees as far as the eye can see.

Maybe, maybe, EVMs from silicon vendors will still boot, but I doubt any other
customer board will work.

> -- 
> Catalin
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Regards

-- Pantelis