Re: [OE-core] [PATCH v2] kernel-fit-image: enable compatible string for kernel built-in DTBs

["Antonin Godard" <antonin.godard@bootlin.com>]

On Mon Oct 13, 2025 at 7:53 AM CEST, Kavinaya S via lists.openembedded.org wrote:
> At present, the kernel-fit-image bbclass is adding compatible strings only
> for external DTBs, omitting them for DTBs built from the kernel tree. This
> behavior is limiting the ability to clearly identify the DTBs in FIT image
> that includes multiple kernel built-in DTBs and possibly mix of in tree and
> external ones, due to lack of consistent compatible strings.
>
> To fix this, introduce a new BitBake variable, FIT_DTB_ADD_COMPATIBLE
> when set to "True", the bbclass will extract and include the compatible
> string from kernel-built DTBs also in the .its file, just like it does
> for external DTBs.
>
> Signed-off-by: Kavinaya S <kavinaya@qti.qualcomm.com>
> ---
>  meta/classes-recipe/kernel-fit-image.bbclass | 3 ++-
>  meta/conf/image-fitimage.conf                | 3 +++
>  2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/meta/classes-recipe/kernel-fit-image.bbclass b/meta/classes-recipe/kernel-fit-image.bbclass
> index f04aee1807..3aa7a2e75a 100644
> --- a/meta/classes-recipe/kernel-fit-image.bbclass
> +++ b/meta/classes-recipe/kernel-fit-image.bbclass
> @@ -85,7 +85,8 @@ python do_compile() {
>              # Copy the dtb or dtbo file into the FIT image assembly directory
>              shutil.copyfile(os.path.join(kernel_deploydir, dtb_name), dtb_name)
>              root_node.fitimage_emit_section_dtb(dtb_name, dtb_name,
> -                d.getVar("UBOOT_DTB_LOADADDRESS"), d.getVar("UBOOT_DTBO_LOADADDRESS"))
> +                d.getVar("UBOOT_DTB_LOADADDRESS"), d.getVar("UBOOT_DTBO_LOADADDRESS"),
> +                add_compatible = bb.utils.to_boolean(d.getVar("FIT_DTB_ADD_COMPATIBLE"), False))
>  
>      if external_kernel_devicetree:
>          # iterate over all .dtb and .dtbo files in the external kernel devicetree directory
> diff --git a/meta/conf/image-fitimage.conf b/meta/conf/image-fitimage.conf
> index 090ee148f4..35e0459d09 100644
> --- a/meta/conf/image-fitimage.conf
> +++ b/meta/conf/image-fitimage.conf
> @@ -47,6 +47,9 @@ FIT_LINUX_BIN ?= "linux.bin"
>  # Allow user to select the default DTB for FIT image when multiple dtb's exists.
>  FIT_CONF_DEFAULT_DTB ?= ""
>  
> +# Allow user to choose if DTB in FIT image can have compatible strings.
> +FIT_DTB_ADD_COMPATIBLE ?= "False"

Hi,

If this is merged can you please send a patch documenting this variable, on
docs@lists.yoctoproject.org?

This should be added to the glossary:
https://git.yoctoproject.org/yocto-docs/tree/documentation/ref-manual/variables.rst

Thanks!
Antonin

-- 
Antonin Godard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com