[PATCH] kbuild: Set NOSTDINC_FLAGS late to speed up compile (a little)
Move definition of NOSTDINC_FLAGS below inclusion of arch Makefile, so
any arch specific settings to $(CC) takes effect before looking up the
compiler include directory.
The previous solution that replaced ':=' with '=' caused gcc to be
invoked one additional time for each directory visited.
This decreases kernel compile time with 0.1 second (3.6 -> 3.5 seconds) when
running make on a fully built kernel
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Makefile b/Makefile
index 8da3a30..4899089 100644
--- a/Makefile
+++ b/Makefile
@@ -332,9 +332,7 @@
PERL = perl
CHECK = sparse
-NOSTDINC_FLAGS = -nostdinc -isystem $(shell $(CC) -print-file-name=include)
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__
-CHECKFLAGS += $(NOSTDINC_FLAGS)
MODFLAGS = -DMODULE
CFLAGS_MODULE = $(MODFLAGS)
AFLAGS_MODULE = $(MODFLAGS)
@@ -531,6 +529,10 @@
include $(srctree)/arch/$(ARCH)/Makefile
+# arch Makefile may override CC so keep this after arch Makefile is included
+NOSTDINC_FLAGS := -nostdinc -isystem $(shell $(CC) -print-file-name=include)
+CHECKFLAGS += $(NOSTDINC_FLAGS)
+
# warn about C99 declaration after statement
CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)