Re: [PATCH 1/2] conf: machine: add BeagleBone Green Eco to KERNEL_DEVICETREE

[Miguel Gazquez <miguel.gazquez@bootlin.com>]

Le 15/07/2025 à 15:52, Ryan Eatmon a écrit :
> 
> 
> On 7/15/2025 6:34 AM, Miguel Gazquez wrote:
>> Add am335x-bonegreen-eco devicetree to KERNEL_DEVICETREE in ti33x.inc
>>
>> Signed-off-by: Miguel Gazquez <miguel.gazquez@bootlin.com>
>> ---
>>   meta-ti-bsp/conf/machine/include/ti33x.inc | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/meta-ti-bsp/conf/machine/include/ti33x.inc b/meta-ti-bsp/ 
>> conf/machine/include/ti33x.inc
>> index 
>> 7e9eb48c52737e74750565e639956334162432e2..0a0730eae104371d65548588b3333839857a3a50 100644
>> --- a/meta-ti-bsp/conf/machine/include/ti33x.inc
>> +++ b/meta-ti-bsp/conf/machine/include/ti33x.inc
>> @@ -28,6 +28,7 @@ KERNEL_DEVICETREE = " \
>>       ti/omap/am335x-boneblack.dtb \
>>       ti/omap/am335x-boneblue.dtb \
>>       ti/omap/am335x-bonegreen-wireless.dtb \
>> +    ti/omap/am335x-bonegreen-eco.dtb \
>>       ti/omap/am335x-bonegreen.dtb \
>>       ti/omap/am335x-chiliboard.dtb \
>>       ti/omap/am335x-cm-t335.dtb \
> 
> NAK.  As has been mentioned several times on this list, we do not update 
> KERNEL_DEVICETREE directly.  As we support multiple kernel versions with 
> each branch, we cannot have a single KERNEL_DEVICETREE that works for 
> all kernel versions.
> 
> To that end we setup the KERNEL_DEVICETREE_PREFIX variable that will 
> pattern match and change the value for KERNEL_DEVICETREE based on the 
> available matching DTBs in the given kernel.  The only kernel version 
> that uses KERNEL_DEVICETREE is the mainline (aka latest stable) kernel. 
> And the value for this variable is automatically updated to include all 
> of the available DTBs in the mainline kernel at the time we update the 
> recipe to that version.
> 
> As the KERNEL_DEVICETREE_PREFIX already has an entry that will pick up 
> this new DTB when it is available, this change is not needed.

When building for the am335x_evm without this patch, the devicetree for 
the beaglebone green eco is not included in the wic image, so the kernel 
can't boot.

As you said, in the linux-ti-staging recipe, KERNEL_DEVICETREE does 
contains the dtb for the bbg eco.

But core-image-minimal (which create the wic image) uses the value of 
KERNEL_DEVICETREE from ti33x.inc, and not the one generated from 
KERNEL_DEVICETREE_PREFIX, so it doesn't contains the devicetree for the 
bbge. This can be checked with `bitbake-getvar -r core-image-minimal 
KERNEL_DEVICETREE`.

It probably works for others boards because, apart from the bbge, there 
isn't any board supported in ti-linux-6.12.y but not in mainline.

If we can't modify KERNEL_DEVICETREE here, what should I do to include 
the devicetree into the final image ?

> 
> Right now this new DTB is only available on linux-next and has not made 
> it into any released kernels.
> 
> 

-- 
Miguel Gazquez, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com