Re: [PATCH 1/2] board: ti: am62x: am62x.env: Fix boot_targets

[Jon Humphreys <j-humphreys@ti.com>]

Andrew Davis <afd@ti.com> writes:

>>>>>>>>      * uEnv.txt processing
>>>>>>>
>>>>>>> What command can do this?
>>>>>>>
>>>>>>
>>>>>> run envboot;
>>>>>>
>>>>>> https://source.denx.de/u-boot/u-boot/-/blob/master/include/env/ti/mmc.env?ref_type=heads#L20
>>>>>
>>>>> This could be a new bootmeth which looks for uenv.txt on available
>>>>> devices. It might be better to put the env in a FIT or something with
>>>>> a checksum.
>> 
>> We use non-FIT boot as well for our non HS platforms, I think the new
>> bootmeth might be helpful as you mentioned, would have to look at this
>> more as I thought bootmeth is supposed to boot a platform at the end
>> only but it seems like here we'll be combining this bootmeth ( that'll
>> just import the env ) and then other bootmeth will actually boot Linux.
>> 
>
> As long as bootmeths can perform an action then continue with other
> bootmeths that could work. This might require complex logic though.
> For instance the uenv.txt bootmeth would only need run on some subset
> of available bootdevs, and it should scan all those devs for uenv.txt
> first, before the Linux finding bootmeths start.
>

It doesn't make sense to treat envboot as a bootmeth because it's really
not about a way of booting but more often just used to modify
environment variables before going through another boot flow (although
you could define/run env variables that performs it's own boot).  It may be
better to think of it as a preprocessing step before a bootflow scan.

Some other thoughts - envboot is more of a hacky way to solve things:
1) As we move more towards secure boot as the standard, we should
   understand what use cases the hacks are working around and properly
   support those use cases.
2) But I don't think we should just remove it altogether because it is a
   very powerful 'feature' during the development phases to try out
   changes without modifying/rebuilding/reflashing u-boot.
3) This is a TI feature.  Are others solving this need in a better way?

Jon