path: root/scripts/Makefile.lib
diff options
authorMasahiro Yamada <yamada.masahiro@socionext.com>2018-03-23 22:04:39 +0900
committerMasahiro Yamada <yamada.masahiro@socionext.com>2018-04-07 19:04:02 +0900
commit54a702f70589926acf687f0cd5df24d07230c80e (patch)
tree210bc0e7df3f7a73218bafeaac9469f20ebe7914 /scripts/Makefile.lib
parent4fa8bc949de11c99ee2433c602d43f87c452f4f2 (diff)
kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers
GNU Make automatically deletes intermediate files that are updated in a chain of pattern rules. Example 1) %.dtb.o <- %.dtb.S <- %.dtb <- %.dts Example 2) %.o <- %.c <- %.c_shipped A couple of makefiles mark such targets as .PRECIOUS to prevent Make from deleting them, but the correct way is to use .SECONDARY. .SECONDARY Prerequisites of this special target are treated as intermediate files but are never automatically deleted. .PRECIOUS When make is interrupted during execution, it may delete the target file it is updating if the file was modified since make started. If you mark the file as precious, make will never delete the file if interrupted. Both can avoid deletion of intermediate files, but the difference is the behavior when Make is interrupted; .SECONDARY deletes the target, but .PRECIOUS does not. The use of .PRECIOUS is relatively rare since we do not want to keep partially constructed (possibly corrupted) targets. Another difference is that .PRECIOUS works with pattern rules whereas .SECONDARY does not. .PRECIOUS: $(obj)/%.lex.c works, but .SECONDARY: $(obj)/%.lex.c has no effect. However, for the reason above, I do not want to use .PRECIOUS which could cause obscure build breakage. The targets specified as .SECONDARY must be explicit. $(targets) contains all targets that need to include .*.cmd files. So, the intermediates you want to keep are mostly in there. Therefore, mark $(targets) as .SECONDARY. It means primary targets are also marked as .SECONDARY, but I do not see any drawback for this. I replaced some .SECONDARY / .PRECIOUS markers with 'targets'. This will make Kbuild search for non-existing .*.cmd files, but this is not a noticeable performance issue. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Frank Rowand <frowand.list@gmail.com> Acked-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'scripts/Makefile.lib')
1 files changed, 0 insertions, 3 deletions
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 7f5bca0c3b7b..07d07409f16f 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -184,7 +184,6 @@ endef
quiet_cmd_flex = LEX $@
cmd_flex = $(LEX) -o$@ -L $<
-.PRECIOUS: $(obj)/%.lex.c
$(obj)/%.lex.c: $(src)/%.l FORCE
$(call if_changed,flex)
@@ -193,14 +192,12 @@ $(obj)/%.lex.c: $(src)/%.l FORCE
quiet_cmd_bison = YACC $@
cmd_bison = $(YACC) -o$@ -t -l $<
-.PRECIOUS: $(obj)/%.tab.c
$(obj)/%.tab.c: $(src)/%.y FORCE
$(call if_changed,bison)
quiet_cmd_bison_h = YACC $@
cmd_bison_h = bison -o/dev/null --defines=$@ -t -l $<
-.PRECIOUS: $(obj)/%.tab.h
$(obj)/%.tab.h: $(src)/%.y FORCE
$(call if_changed,bison_h)