Re: [OE-core] [PATCH v7] kernel-fit-image: allow overriding DTB compatible string

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

On Wed Oct 15, 2025 at 10:05 AM 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 override the compatible string
> using a BitBake variable:
> FIT_DTB_COMPATIBLE_OVERRIDE[<dtb_name>] = "<compatible_string>"
>
> This overrides the compatible string generated resulting in unique entries in the
> generated .its file. For example:
> FIT_DTB_COMPATIBLE_OVERRIDE[qcs6490-rb3gen2-vision-mezzanine] = "qcom,qcs6490-rb3gen2-vision"
> FIT_DTB_COMPATIBLE_OVERRIDE[qcs6490-rb3gen2-vision-mezzanine] = "qcom,qcs6490-rb3gen2-vision qcom,qcm6490"
>
> Results in:
>
> compatible = "qcom,qcs6490-rb3gen2-vision";
> compatible = "qcom,qcs6490-rb3gen2-vision", "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,

Thanks for the new version. However, I still got a similar issue:

ERROR: linux-yocto-6.16.9+git-r0 do_compile: Execution of '/srv/pokybuild/yocto-worker/oe-selftest-armhost/build/build-st-1723335/tmp/work/qemuarm64-poky-linux/linux-yocto/6.16.9+git/temp/run.do_compile.365769' failed with exit code 1
...
| make[2]: *** No rule to make target 'arch/arm64/boot/dts/am335x-bonegreen-ext.dtb'.  Stop.

https://autobuilder.yoctoproject.org/valkyrie/#/builders/23/builds/2701
https://autobuilder.yoctoproject.org/valkyrie/#/builders/35/builds/2549
https://autobuilder.yoctoproject.org/valkyrie/#/builders/48/builds/2463

Can you have a look at this please?

Thanks,
Mathieu

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