kbuild: make V=2 tell why a target is rebuild
tell why a a target got build
enabled by make V=2
Output (listed in the order they are checked):
(1) - due to target is PHONY
(2) - due to target missing
(3) - due to: file1.h file2.h
(4) - due to command line change
(5) - due to missing .cmd file
(6) - due to target not in $(targets)
(1) We always build PHONY targets
(2) No target, so we better build it
(3) Prerequisite is newer than target
(4) The command line stored in the file named dir/.target.cmd
differed from actual command line. This happens when compiler
options changes
(5) No dir/.target.cmd file (used to store command line)
(6) No dir/.target.cmd file and target not listed in $(targets)
This is a good hint that there is a bug in the kbuild file
This patch is inspired by a patch from: Milton Miller <miltonm@bga.com>
Cc: Milton Miller <miltonm@bga.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Makefile b/Makefile
index 22451c2..440a133 100644
--- a/Makefile
+++ b/Makefile
@@ -1101,6 +1101,7 @@
echo '')
@echo ' make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
+ @echo ' make V=2 [targets] 2 => give reason for rebuild of target'
@echo ' make O=dir [targets] Locate all output files in "dir", including .config'
@echo ' make C=1 [targets] Check all c source with $$CHECK (sparse by default)'
@echo ' make C=2 [targets] Force check of all c source with $$CHECK'