[U-Boot] dtb vs. kernel command line arguments

[Simon Glass]

Hi Kim,

On Mon, Mar 4, 2013 at 4:03 PM, Kim Phillips <kim.phillips at freescale.com> wrote:
> On Mon, 4 Mar 2013 10:30:45 -0800
> Curt Brune <curt at cumulusnetworks.com> wrote:
>
>> Hello -
>>
>> I want to pass a number of arguments from u-boot to the booted kernel.
>> The arguments are needed by user space applications, not the kernel.
>>
>> I can think of two ways:
>>
>> 1. append args by setting "bootargs".
>> 2. add nodes to the dtb before booting.
>>
>> Is there a preferred way to pass information like this?
>>
>> Like I said the arguments are not needed by the kernel device drivers,
>> but by user space applications.
>>
>> I like the structure of nodes in the dtb.
>
> please don't dual-purpose device trees as a mechanism of getting
> arguments through the kernel into userspace - device trees strictly
> describe the hardware.

That's certainly the primary purpose, but it is also true that the
device tree is a convenient way to pass things to the kernel. It is in
fact becoming the only way on ARM systems. We certainly use it to pass
general information to the kernel, for example the command line.

Regards,
Simon

>
> btw, this question would be more appropriately posted on
> devicetree-discuss (in case you have more).
>
> Kim
>
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