[U-Boot] [RFC PATCH] arm: bootm: Boot kernel with U-Boot's FDT blob

[Ryan Harkin]

On 12 January 2017 at 12:25, Mark Rutland <mark.rutland at arm.com> wrote:
> On Tue, Jan 10, 2017 at 06:50:19PM +0000, Jon Medhurst (Tixy) wrote:
>> On Tue, 2017-01-10 at 18:34 +0000, Mark Rutland wrote:
>> > Looking at the git log for arch/arm64/boot/dts/arm, most updates are
>> > simply adding new descriptions, so a DTB from a year ago should work
>> > just fine with mainline (modulo the Juno PCI window issue, which was a
>> > DTB bug). Upgrading kernel shouldn't require a DTB upgrade to see
>> > equivalent functionality.
>>
>> But if you want the new functionality in the kernel, why should you be
>> forced to wait for the bootloader to catch up (or do that work yourself)
>> then upgrade to that new bootloader version? And what about the poor
>> devs working on that new functionality, they're going to need to use not
>> upstream device-trees. Then there's all the firmware and system
>> configuration stuff that's in device-tree.
>
> Developers working on low-level stuff will always need to be able to
> override/upgrade/etc. I am certainly not arguing to remove those
> capabilities.
>
> The key point is that it is possible to provide a baseline DTB that is
> good enough for most users, and will work with future kernels.
>
> We're unlikely to get to a state where DTBs are perfect and complete
> from day one. We can have something that remains usable.
>

I hope it stays that way. Most of my users are either on 3.18 or 4.4.
And they are incompatible with each other w.r.t. DTBs to the point
where one won't even post a banner message with the other's DTB.

> Thanks,
> Mark.