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Commit e8e6993178344eb348f60f05b16d9dc30db3b9cf

Authored by Sam Ravnborg
Committed by Linus Torvalds
1 parent b3d9ae4b98
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[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>

Showing 1 changed file with 4 additions and 2 deletions Side-by-side Diff

... ... @@ -332,9 +332,7 @@
332 332 PERL = perl
333 333 CHECK = sparse
334 334  
335   -NOSTDINC_FLAGS = -nostdinc -isystem $(shell $(CC) -print-file-name=include)
336 335 CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__
337   -CHECKFLAGS += $(NOSTDINC_FLAGS)
338 336 MODFLAGS = -DMODULE
339 337 CFLAGS_MODULE = $(MODFLAGS)
340 338 AFLAGS_MODULE = $(MODFLAGS)
... ... @@ -530,6 +528,10 @@
530 528 endif
531 529  
532 530 include $(srctree)/arch/$(ARCH)/Makefile
  531 +
  532 +# arch Makefile may override CC so keep this after arch Makefile is included
  533 +NOSTDINC_FLAGS := -nostdinc -isystem $(shell $(CC) -print-file-name=include)
  534 +CHECKFLAGS += $(NOSTDINC_FLAGS)
533 535  
534 536 # warn about C99 declaration after statement
535 537 CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)