build: add buildinfo as single Makefile target

The prepare target was added some 11 years ago to build tools and
toolchain and was recently extended to  create buildinfo files for
reproducibility, meaning {feeds,version,config}.buildinfo.

As the buildbot workflow is more complex than the single prepare (kmod
feed insertion), prepare is only used to create those buildinfo files.
Running prepare however runs `target/compile` as well, taking time even
everything is already compiled.

Splitting this allows the buildbot to run only the `buildinfo` target
while others can still use the convenience feature `prepare`.

Signed-off-by: Paul Spooren <mail@aparcar.org>

diff --git a/Makefile b/Makefile
index 65ee10a84b8d57c5bfed7047f0ed114a78190df1..181c33b180f2016f6e1ce33c96b53791980ce940 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -100,9 +100,12 @@ diffconfig: FORCE
        mkdir -p $(BIN_DIR)
        $(SCRIPT_DIR)/diffconfig.sh > $(BIN_DIR)/config.buildinfo
 
-prepare: .config $(tools/stamp-compile) $(toolchain/stamp-compile)
+buildinfo: FORCE
        $(_SINGLE)$(SUBMAKE) -r diffconfig buildversion feedsversion
 
+prepare: .config $(tools/stamp-compile) $(toolchain/stamp-compile)
+       $(_SINGLE)$(SUBMAKE) -r buildinfo
+
 world: prepare $(target/stamp-compile) $(package/stamp-compile) $(package/stamp-install) $(target/stamp-install) FORCE
        $(_SINGLE)$(SUBMAKE) -r package/index
        $(_SINGLE)$(SUBMAKE) -r checksum