kbuild: correct and clarify versioning info in Makefile
The attached patch clarifies the creation of KERNELRELEASE and
corrects an error regarding the use of $(LOCALVERSION).
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Makefile b/Makefile
index 13bc589..241fed3 100644
--- a/Makefile
+++ b/Makefile
@@ -760,12 +760,34 @@
$(Q)$(MAKE) $(build)=$@
# Build the kernel release string
-# The KERNELRELEASE is stored in a file named include/config/kernel.release
-# to be used when executing for example make install or make modules_install
#
-# Take the contents of any files called localversion* and the config
-# variable CONFIG_LOCALVERSION and append them to KERNELRELEASE.
-# LOCALVERSION from the command line override all of this
+# The KERNELRELEASE value built here is stored in the file
+# include/config/kernel.release, and is used when executing several
+# make targets, such as "make install" or "make modules_install."
+#
+# The eventual kernel release string consists of the following fields,
+# shown in a hierarchical format to show how smaller parts are concatenated
+# to form the larger and final value, with values coming from places like
+# the Makefile, kernel config options, make command line options and/or
+# SCM tag information.
+#
+# $(KERNELVERSION)
+# $(VERSION) eg, 2
+# $(PATCHLEVEL) eg, 6
+# $(SUBLEVEL) eg, 18
+# $(EXTRAVERSION) eg, -rc6
+# $(localver-full)
+# $(localver)
+# localversion* (all localversion* files)
+# $(CONFIG_LOCALVERSION) (from kernel config setting)
+# $(localver-auto) (only if CONFIG_LOCALVERSION_AUTO is set)
+# ./scripts/setlocalversion (SCM tag, if one exists)
+# $(LOCALVERSION) (from make command line if provided)
+#
+# Note how the final $(localver-auto) string is included *only* if the
+# kernel config option CONFIG_LOCALVERSION_AUTO is selected. Also, at the
+# moment, only git is supported but other SCMs can edit the script
+# scripts/setlocalversion and add the appropriate checks as needed.
nullstring :=
space := $(nullstring) # end of line