bitbake: doc: enhance SRCREV_FORMAT description

Adding documentation for having an empty first component for the
SRCREV_FORMAT.

(Bitbake rev: 37ef26cfd5441ce97ff7ec0d5026c92091224c07)

Signed-off-by: Patrick Vogelaar <patrick.vogelaar.dev@mailbox.org>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
index ac8e06392d..d091334a44 100644
--- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
+++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
@@ -1688,6 +1688,12 @@ overview of their function and contents.
       ``AUTOINC`` placeholder is added and if needed. And, this placeholder
       is placed at the start of the returned string.
 
+      The :term:`SRCREV_FORMAT` can also take the form "_component2".
+      This assumes that there is a component in the :term:`SRC_URI` that does not
+      have a name assigned. While this is not considered good practice, it can be
+      usefull if a ``.bbappend`` file needs to extend the :term:`SRC_URI` with
+      an additional repository.
+
    :term:`STAMP`
       Specifies the base path used to create recipe stamp files. The path
       to an actual stamp file is constructed by evaluating this string and