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

[Ryan Harkin]

On 10 January 2017 at 16:35, Alexander Graf <agraf at suse.de> wrote:
> On 01/10/2017 05:31 PM, york sun wrote:
>>
>> On 01/10/2017 05:02 AM, Alexander Graf wrote:
>>>
>>> On 01/10/2017 01:58 PM, Michal Simek wrote:
>>>>
>>>> U-Boot configured via DTB can use the same DTB for booting the kernel.
>>>> When OF_CONTROL is used fdtcontroladdr is setup and can be use for boot.
>>>>
>>>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>>>> ---
>>>>
>>>> Didn't check if there is any side effect or not but it looks weird when
>>>> you have DT driver u-boot that you have to load dtb again.
>>>
>>> I agree, and I think it's very reasonable to try and use the same device
>>> tree for U-Boot and Linux.
>>>

Would this prevent the user loading a DTB into ram and using bootm to
over-ride the built-in DTB?

I have a background task to refactor u-boot support for ARM Ltd
boards. One of many options I was considering was to have a minimal
DTB to configure the platform with only the nodes needed for u-boot.
The ARM Ltd device trees fluctuate so much, I wouldn't be able to
commit to one DTB that will work forever...


>> Size is a concern. U-Boot only uses a small portion of the device tree.
>> If the complete device tree is embedded into U-Boot, the size increases
>> quite a bit.
>
>
> Is size really a concern? At the end of the day we only care about the full
> dt for non-SPL U-Boot which is reasonably big anyway. And if it's a real
> problem, we can always compress.
>
>
> Alex
>
>
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