Re: [OE-core] [PATCH v6] kernel-fit-image: allow extending compatible string property for DTBs

["Mathieu Dubois-Briand" <mathieu.dubois-briand@bootlin.com>]

On Sun Oct 12, 2025 at 6:24 PM CEST, Kavinaya S via lists.openembedded.org wrote:
> The Linux kernel allows multiple DTBs to share the same compatible string.
> For example:
> qcs6490-rb3gen2.dtb
> qcs6490-rb3gen2-vision-mezzanine.dtb
> qcs6490-rb3gen2-industrial-mezzanine.dtb
>
> All of these use the same base compatible string:
> compatible = "qcom,qcs6490-rb3gen2", "qcom,qcm6490";
>
> Since the latter two DTBs are overlays on top of the base DTB and do not
> modify platform properties, they retain the same compatible string.
>
> When these DTBs are bundled into a single fitImage, the bootloader cannot
> distinguish between them due to identical compatible strings.
>
> To address this, introduce a mechanism to extend the compatible string
> using a OE build variable:
> FIT_DTB_COMPATIBLE_EXTENSION[dtb_name] = "extension"
>
> This appends the extension to the first compatible string in the DTB,
> resulting in unique entries in the generated .its file. For example:
> FIT_DTB_COMPATIBLE_EXTENSION[qcs6490-rb3gen2-vision-mezzanine] = "vision"
> FIT_DTB_COMPATIBLE_EXTENSION[qcs6490-rb3gen2-industrial-mezzanine] = "industrial"
>
> Generates:
> compatible = "qcom,qcs6490-rb3gen2-vision", "qcom,qcm6490";
> compatible = "qcom,qcs6490-rb3gen2-industrial", "qcom,qcm6490";
>
> Suggested-By: Alexander Kanavin <alex.kanavin@gmail.com>
> Suggested-By: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Signed-off-by: Kavinaya S <kavinaya@qti.qualcomm.com>
> ---

Hi Kavinaya,

We suspect this series is responsible for a break on Richard master-next
branch. This seems either a bit intermittent or a bad interaction with
something else, as I don't have a similar issue here. Still, dropping
the patch fixes the issue, so there is probably something bad in there.

ERROR: linux-yocto-6.16.9+git-r0 do_compile: Execution of '/srv/pokybuild/yocto-worker/oe-selftest-debian/build/build-st-1431372/tmp/work/qemux86_64-poky-linux/linux-yocto/6.16.9+git/temp/run.do_compile.555534' failed with exit code 1
...
| make[1]: *** No rule to make target 'am335x-bonegreen.dtb'.  Stop.

https://autobuilder.yoctoproject.org/valkyrie/#/builders/35/builds/2530

Can you have a look at this error please?

Thanks,
Mathieu

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com