ref-manual: SYSTEMD_SERVICE overrides depend on SYSTEMD_PACKAGES

Add detail that package overrides are only available if
specified in SYSTEMD_PACKAGES.

(From yocto-docs rev: 9466c0b79348e68b1db7aefd3d95f8e7c903f1d4)

Signed-off-by: Paulo Neves <ptsneves@gmail.com>
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 42178d556d..e31f0ed886 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -7664,6 +7664,10 @@ system and gives an overview of their function and contents.
 
          SYSTEMD_SERVICE:${PN} = "connman.service"
 
+      The package overrides that can be specified are directly related to the value of
+      term:`SYSTEMD_PACKAGES`. Overrides not included in term:`SYSTEMD_PACKAGES`
+      will be silently ignored.
+
    :term:`SYSVINIT_ENABLED_GETTYS`
       When using
       :ref:`SysVinit <dev-manual/common-tasks:enabling system services>`,