conf/bitbake.conf: add DISTRO_FEATURES_BACKFILL

When introducing new items to DISTRO_FEATURES that control functionality
that is already enabled, in order to leave existing distro configuration
unchanged we need a way to "backfill" these new feature items onto the
existing DISTRO_FEATURES value.

This introduces a DISTRO_FEATURES_BACKFILL variable whose items will be
added to the end of DISTRO_FEATURES, unless they also appear in
DISTRO_FEATURES_BACKFILL_CONSIDERED which distros can use in their
configuration to prevent specific items from being added.

Fixes [YOCTO #1946].

(From OE-Core rev: 738658d9d5ddef026d2929188744aa225324bf26)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index 90e5f7a3bc..2539ae0f0a 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -694,6 +694,9 @@ MACHINE_ESSENTIAL_EXTRA_RDEPENDS ?= ""
 MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS ?= ""
 IMAGE_FEATURES += "${EXTRA_IMAGE_FEATURES}"
 
+DISTRO_FEATURES_BACKFILL = ""
+DISTRO_FEATURES_append = "${@oe.utils.distro_features_backfill(d)}"
+
 COMBINED_FEATURES = "\
     ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "alsa", d)} \
     ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "bluetooth", d)} \