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

Tue Nov 28 10:31:58 CET 2023

Hi Simon,

On 12:05-20231106, Andrew Davis wrote:
> On 11/6/23 11:47 AM, Simon Glass wrote:
> > Hi Andrew,
> > 
> > On Mon, 6 Nov 2023 at 10:27, Andrew Davis <afd at ti.com> wrote:
> > > 
> > > 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)
> > 
> > What does this mean? Can you please be more specific or give an example?
> > 
> 
> Sure, for instance with secure boot we only want to search for FIT images
> and if for each media this fails we do not want to fall back to other
> image types or boot modes (like UART boot or net boot which would bypass
> the signature checks).
> 
> Something similar is needed for searching for EFI compatible boot across
> each enabled boot media first, before trying other methods on each media.
> Basically breadth-first search on each media type not depth-first.
> 
> > >    * fetching and applying FIT overlay/config strings
> > 
> > Re overlays, is this the 'extension' command? What are config strings?
> > 
> 
> When we have DT overlays in our FIT image, we build a string to pass to
> bootm to apply all the selected overlays[0]. If there is now another
> mechanism for this please let me know (building this string today is messy).
> 
> https://source.denx.de/u-boot/u-boot/-/blob/master/include/env/ti/ti_common.env?ref_type=heads#L18
> 
> > >    * remote proc loading
> > 
> > What command can do this?
> > 
> 
> https://source.denx.de/u-boot/u-boot/-/blob/master/include/env/ti/ti_common.env?ref_type=heads#L28
> 
> > >    * 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
> 
> > > 
> > > 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.
> > 
> > I'm happy to help figure this out.
> > 
> 
> Thanks, we are eager to standardize our boot flows and stdboot seems like the
> right way forward, very happy to have your guidance on these last few items :)
> 
> Andrew

Any nudges on the Andrew's response as to where we can look for all
this or how can we maybe move towards all this?

Regards,
Manorit

> 
> > Regards,
> > SImon