Re: [PATCH 2/2] Documentation: user: barebox: mention generic dt 2nd stage support

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 07.02.22 09:34, Sascha Hauer wrote:
> On Mon, Feb 07, 2022 at 09:14:51AM +0100, Ahmad Fatoum wrote:
>> Hello Sascha,
>>
>> On 07.02.22 09:00, Sascha Hauer wrote:
>>> On Sun, Feb 06, 2022 at 12:19:30AM +0100, Ahmad Fatoum wrote:
>>>> Most users interested in chainloading barebox will probably want to use
>>>> the generic DT format for that: It will pass the checks the boot command
>>>> may have and it will ensure the system is in the correct state, e.g.
>>>> that caches are disabled.
>>>>
>>>> Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
>>>> ---
>>>>  Documentation/user/barebox.rst | 18 +++++++++++++++---
>>>>  1 file changed, 15 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/Documentation/user/barebox.rst b/Documentation/user/barebox.rst
>>>> index 8634d8e48eef..4abcf79c6d2a 100644
>>>> --- a/Documentation/user/barebox.rst
>>>> +++ b/Documentation/user/barebox.rst
>>>> @@ -203,9 +203,21 @@ Starting barebox
>>>>  Bringing barebox to a board for the first time is highly board specific, see your
>>>>  board documentation for initial bringup.
>>>>  
>>>> -barebox binaries are, where possible, designed to be startable second stage from another
>>>> -bootloader. For example, if you have U-Boot running on your board, you can start barebox
>>>> -with U-Boot's ``bootm`` command:
>>>> +For ARM and RISC-V, the barebox build can additionally generate a generic DT image
>>>> +(enable ``CONFIG_BOARD_ARM_GENERIC_DT`` or ``CONFIG_BOARD_RISCV_GENERIC_DT``,
>>>> +respectively). The resulting ``images/barebox-dt-2nd.img`` can be booted just
>>>> +like a Linux kernel that is passed an external device tree. For example:
>>>> +
>>>> +.. code-block:: console
>>>> +
>>>> +  U-Boot: tftp $kernel_addr barebox-dt-2nd.img
>>>> +  U-Boot: tftp $fdt_addr my-board.dtb
>>>> +  U-Boot: booti $kernel_addr - $fdt_addr
>>>> +
>>>> +For non-DT enabled-bootloaders or other architectures, often the normal barebox
>>>> +binaries can also be used as they are designed to be startable second stage
>>>> +from another bootloader, where possible. For example, if you have U-Boot running
>>>> +on your board, you can start barebox with U-Boot's ``bootm`` command:
>>>
>>> Hm, that seems wrong. U-Boot's bootm command starts images generated
>>> with U-Boot's mkimage tool. A raw barebox image cannot be started with
>>> this command, one has to create a uImage from it before.
>>
>> This is what the documentation is saying right now. It only appeared
>> in the diff, because I rephrased the start a bit. I don't have a
>> 32-bit ARM U-Boot here to test, so I'd rather not rewrite that part
>> myself.
> 
> Well you've introduced the part to use the bootm command yourself :)
> 
> commit 3a14fb79153af84323fee8308989011cd05c7d96
> Author: Ahmad Fatoum <a.fatoum@pengutronix.de>
> Date:   Mon Jun 17 16:18:46 2019 +0200
> 
> However, I obviously failed to review this properly. I'll create a patch
> for that.

Aua :D

> 
> Sascha
> 


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