bitbake: bitbake: improve descriptions of '-S printdiff'

(Bitbake rev: becf88c2250a47102c8d36ad8b40839e0bfa9137)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 7 insertions, 4 deletions

diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-execution.rst b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-execution.rst
index 4fa3ca4b54..d58fbb32ea 100644
--- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-execution.rst
+++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-execution.rst
@@ -586,10 +586,11 @@ or possibly those defined in the metadata/signature handler itself. The
 simplest parameter to pass is "none", which causes a set of signature
 information to be written out into ``STAMPS_DIR`` corresponding to the
 targets specified. The other currently available parameter is
-"printdiff", which causes BitBake to try to establish the closest
+"printdiff", which causes BitBake to try to establish the most recent
 signature match it can (e.g. in the sstate cache) and then run
-``bitbake-diffsigs`` over the matches to determine the stamps and delta
-where these two stamp trees diverge.
+compare the matched signatures to determine the stamps and delta
+where these two stamp trees diverge. This can be used to determine why
+tasks need to be re-run in situations where that is not expected.
 
 .. note::
 
diff --git a/bitbake/lib/bb/main.py b/bitbake/lib/bb/main.py
index 92d8dc0293..bca8ebfa09 100755
--- a/bitbake/lib/bb/main.py
+++ b/bitbake/lib/bb/main.py
@@ -217,7 +217,9 @@ def create_bitbake_parser():
                              "execution. The SIGNATURE_HANDLER parameter is passed to the "
                              "handler. Two common values are none and printdiff but the handler "
                              "may define more/less. none means only dump the signature, printdiff"
-                             " means compare the dumped signature with the cached one.")
+                             " means recursively compare the dumped signature with the most recent"
+                             " one in a local build or sstate cache (can be used to find out why tasks re-run"
+                             " when that is not expected)")
 
     exec_group.add_argument("--revisions-changed", action="store_true",
                         help="Set the exit code depending on whether upstream floating "