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

[Andrew Davis]

On 11/6/23 9:31 AM, Tom Rini wrote:
> On Mon, Nov 06, 2023 at 11:23:51AM +0530, Manorit Chawdhry wrote:
>> Hi Simon,
>>
>> On 11:22-20231005, Simon Glass wrote:
>>> Hi Nishanth,
>>>
>>> On Thu, 5 Oct 2023 at 11:16, Nishanth Menon <nm at ti.com> wrote:
>>>>
>>>> On 12:10-20231005, Nishanth Menon wrote:
>>>>> On 12:36-20231005, Tom Rini wrote:
>>>>>> On Thu, Oct 05, 2023 at 09:19:48AM -0500, Andrew Davis wrote:
>>>>>>> On 10/4/23 8:54 AM, Nishanth Menon wrote:
>>>>>>>> On 08:48-20231004, Andrew Davis wrote:
>>>>>>>>> On 10/4/23 8:23 AM, Roger Quadros wrote:
>>>>>>>>>> ti_mmc is not a valid boot_target for standard boot flow so
>>>>>>>>>
>>>>>>>>> Is there some way to make it into a valid boot_target? Otherwise
>>>>>>>>> how do we use uEnv.txt files, or boot from FIT images with overlays?
>>>>>>>>
>>>>>>>> envboot takes care of uEnv.txt file (see
>>>>>>>> https://lore.kernel.org/all/20231004132324.44198-3-rogerq@kernel.org/)
>>>>>>>>
>>>>>>>> Early remote proc loading and FIT image is a question for stdboot itself.
>>>>>>>>
>>>>>>>
>>>>>>> If stdboot is missing these features then we shouldn't switch until it
>>>>>>> has them. I'm all for switching to this, but only if it is complete.
>>>>>>
>>>>>> Depends on what you mean?  Did you mean an option to run scripts
>>>>>> (exists) or an option to do what TI needs done, via
>>>>>> boot/bootmeth_something.c ?  If the latter, someone from TI needs to
>>>>>> figure out what that should be and do (but plumbing-wise everything it
>>>>>> needs should exist).
>>>>>
>>>>> Andrew is generalizing here (on the wrong patch though).
>>>>>
>>>>> On am62x platforms, there is nothing regressing with this series. The
>>>>> challenge is early remote_proc loading which is done for J7* platforms.
>>>>>
>>>>> How that is initiated as part of bootmethods is something of a gap.
>>>>>
>>>>> The other gap has been support for uEnv.txt -> which we can workaround
>>>>> at the moment by using CONFIG_BOOTCOMMAND="run envboot; bootflow scan
>>>>> -lb" in defconfig (This series from Roger already does that - hence I am
>>>>> saying that Andrew is complaining on the wrong series).
>>>>>
>>>>> Ideally, we should just have CONFIG_BOOTCOMMAND="bootflow scan -lb" and
>>>>> uEnv.txt remoteproc loads and the various standard bootmethods should
>>>>> "just work".
>>>>
>>>>
>>>> I forgot to add: FIT image authenticated boot flow. That is really what
>>>> ti_mmc distroboot method was trying to solve.
>>>>
>>>> Maybe Simon or someone know how the stdboot flow handles authenticated
>>>> kernel image and dtb boot flow with FIT image?
>>>
>>> Yes you can use FIT configuration verification and things should work as normal.
>>>
>>
>> Could you give any reference documentation for this?
> 
> I suspect you should start with doc/usage/fit/beaglebone_vboot.rst
> 

 From that doc:

```
Boot the board using the commands below::

     setenv bootargs console=ttyO0,115200n8 quiet root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait
     ext2load mmc 0:2 82000000 /boot/image.fit
     bootm 82000000
```

This is very much not stdboot :( This doc has some good and current info on building
a secure FIT image, but much of it is showing its age. Stdboot is still missing

  * ability to limit boot mode search to only one image (FIT)
  * fetching and applying FIT overlay/config strings
  * remote proc loading
  * uEnv.txt processing

Last two can be solved by adding to CONFIG_BOOTCOMMAND before calling `bootflow scan`
as suggested above. Until we figure out the first two I don't see us ready to switch.

Andrew