From 54a702f70589926acf687f0cd5df24d07230c80e Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 23 Mar 2018 22:04:39 +0900 Subject: 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 Acked-by: Frank Rowand Acked-by: Ingo Molnar --- arch/arm/crypto/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm/crypto') diff --git a/arch/arm/crypto/Makefile b/arch/arm/crypto/Makefile index 3304e671918d..8de542c48ade 100644 --- a/arch/arm/crypto/Makefile +++ b/arch/arm/crypto/Makefile @@ -67,4 +67,4 @@ $(src)/sha512-core.S_shipped: $(src)/sha512-armv4.pl $(call cmd,perl) endif -.PRECIOUS: $(obj)/sha256-core.S $(obj)/sha512-core.S +targets += sha256-core.S sha512-core.S -- cgit v1.2.3