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[1/2] bitbake-setup: clarify configuration merging

Message ID 20260529-bb-setup-notes-v1-1-a251ef1c5af4@toradex.com
State New
Headers show
Series bitbake-setup: clarify configuration merging and add a notes property | expand

Commit Message

Ernest Van Hoecke May 29, 2026, 3 p.m. UTC
From: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>

When nested configurations are used and the same key is present in both
configs being merged, the Python "+" behaviour is used. This leads to
lists being appended and strings being concatenated. The first is an
intuitive behaviour when specifying a tree of configs, the latter might
not be.

Clarify the configuration merging behaviour explicitly in the docs.

Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>
---
 doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Alexander Kanavin May 29, 2026, 4:47 p.m. UTC | #1
Thanks, this lgtm!

Alex

On Fri, 29 May 2026 at 17:00, Ernest Van Hoecke via
lists.openembedded.org
<ernestvanhoecke=gmail.com@lists.openembedded.org> wrote:
>
> From: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>
>
> When nested configurations are used and the same key is present in both
> configs being merged, the Python "+" behaviour is used. This leads to
> lists being appended and strings being concatenated. The first is an
> intuitive behaviour when specifying a tree of configs, the latter might
> not be.
>
> Clarify the configuration merging behaviour explicitly in the docs.
>
> Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>
> ---
>  doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst b/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
> index 77fc4c3dcba0..1252f22c823a 100644
> --- a/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
> +++ b/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
> @@ -1068,6 +1068,12 @@ They contain the following sections:
>        configuration choices by putting together information from a leaf
>        configuration and all of its ancestors.
>
> +      When the same keyword is present in a nested configuration and in one of
> +      its ancestors, the values are merged with Python ``+`` semantics. For
> +      example, lists are appended and strings are concatenated directly. String
> +      values such as ``description`` should include any needed separators in
> +      the configuration data.
> +
>     -  ``bb-env-passthrough-additions`` (*optional*): List of environment
>        variables to include in :term:`BB_ENV_PASSTHROUGH_ADDITIONS`.
>
>
> --
> 2.43.0
>
>
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diff mbox series

Patch

diff --git a/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst b/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
index 77fc4c3dcba0..1252f22c823a 100644
--- a/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
+++ b/doc/bitbake-user-manual/bitbake-user-manual-environment-setup.rst
@@ -1068,6 +1068,12 @@  They contain the following sections:
       configuration choices by putting together information from a leaf
       configuration and all of its ancestors.
 
+      When the same keyword is present in a nested configuration and in one of
+      its ancestors, the values are merged with Python ``+`` semantics. For
+      example, lists are appended and strings are concatenated directly. String
+      values such as ``description`` should include any needed separators in
+      the configuration data.
+
    -  ``bb-env-passthrough-additions`` (*optional*): List of environment
       variables to include in :term:`BB_ENV_PASSTHROUGH_ADDITIONS`.