[U-Boot] u-boot - raspberry pi

[Stephen Warren]

On 08/26/2016 08:39 AM, Simon Glass wrote:
> +Stephen
>
> On 25 August 2016 at 22:12,  <dh at synoia.com> wrote:
>>  We have u-boot working on a raspberry pi, but need to append our kernel
>>  parms to those built by the firmware.
>>
>> is there a version of u-boot for the pi 3, with this support, and some doc
>> (the variable name for the firmware built kernel parms), a github link would
>> be perfect.
>>
>> We have an order of 400 PIs for a hospital in S America, and want to supply
>> net boot, including kernels. Duncan Hare

The current port of U-Boot to the Pi is intended to replace the 
operations that the binary FW performs rather than add to them. As such, 
there's currently no easy way to do what you need with U-Boot.

Two potential options exist:

1) Update U-Boot so that it saves the DTB pointer the binary FW passes 
at boot, parses this DTB, and exposes various properties (its address, 
the command-line embodied within it) as environment variables. U-Boot 
scripts could then use those environment variables as they see fit (e.g. 
ignore them to be compatible with current U-Boot behaviour, or set 
$bootargs by appending the extracted cmdline to whatever you want to add).

2) The binary FW recently grew a network boot feature itself. Perhaps 
this will fulfil your network boot needs by itself, so you don't need to 
use U-Boot.

> https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/net.md

I haven't tried this yet, but it sounds good.