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-rw-r--r--Documentation/kbuild/makefiles.txt15
1 files changed, 9 insertions, 6 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 54bbfd37f157..1ca535bcc8c7 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -294,7 +294,7 @@ more details, with real examples.
294 294
295 295
296 This variable is necessary because the top Makefile owns the 296 This variable is necessary because the top Makefile owns the
297 variable $(CFLAGS) and uses it for compilation flags for the 297 variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
298 entire tree. 298 entire tree.
299 299
300 $(EXTRA_AFLAGS) is a similar string for per-directory options 300 $(EXTRA_AFLAGS) is a similar string for per-directory options
@@ -437,6 +437,7 @@ more details, with real examples.
437 -march=pentium-mmx if supported by $(CC), otherwise -march=i586. 437 -march=pentium-mmx if supported by $(CC), otherwise -march=i586.
438 The second argument to cc-option is optional, and if omitted, 438 The second argument to cc-option is optional, and if omitted,
439 cflags-y will be assigned no value if first option is not supported. 439 cflags-y will be assigned no value if first option is not supported.
440 Note: cc-option uses KBUILD_CFLAGS for $(CC) options
440 441
441 cc-option-yn 442 cc-option-yn
442 cc-option-yn is used to check if gcc supports a given option 443 cc-option-yn is used to check if gcc supports a given option
@@ -452,6 +453,7 @@ more details, with real examples.
452 option. When $(biarch) equals 'y', the expanded variables $(aflags-y) 453 option. When $(biarch) equals 'y', the expanded variables $(aflags-y)
453 and $(cflags-y) will be assigned the values -a32 and -m32, 454 and $(cflags-y) will be assigned the values -a32 and -m32,
454 respectively. 455 respectively.
456 Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options
455 457
456 cc-option-align 458 cc-option-align
457 gcc versions >= 3.0 changed the type of options used to specify 459 gcc versions >= 3.0 changed the type of options used to specify
@@ -463,10 +465,11 @@ more details, with real examples.
463 cc-option-align = -falign 465 cc-option-align = -falign
464 466
465 Example: 467 Example:
466 CFLAGS += $(cc-option-align)-functions=4 468 KBUILD_CFLAGS += $(cc-option-align)-functions=4
467 469
468 In the above example, the option -falign-functions=4 is used for 470 In the above example, the option -falign-functions=4 is used for
469 gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used. 471 gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used.
472 Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options
470 473
471 cc-version 474 cc-version
472 cc-version returns a numerical version of the $(CC) compiler version. 475 cc-version returns a numerical version of the $(CC) compiler version.
@@ -825,17 +828,17 @@ When kbuild executes, the following steps are followed (roughly):
825 #arch/sparc64/Makefile 828 #arch/sparc64/Makefile
826 AFLAGS += -m64 -mcpu=ultrasparc 829 AFLAGS += -m64 -mcpu=ultrasparc
827 830
828 CFLAGS $(CC) compiler flags 831 KBUILD_CFLAGS $(CC) compiler flags
829 832
830 Default value - see top level Makefile 833 Default value - see top level Makefile
831 Append or modify as required per architecture. 834 Append or modify as required per architecture.
832 835
833 Often, the CFLAGS variable depends on the configuration. 836 Often, the KBUILD_CFLAGS variable depends on the configuration.
834 837
835 Example: 838 Example:
836 #arch/i386/Makefile 839 #arch/i386/Makefile
837 cflags-$(CONFIG_M386) += -march=i386 840 cflags-$(CONFIG_M386) += -march=i386
838 CFLAGS += $(cflags-y) 841 KBUILD_CFLAGS += $(cflags-y)
839 842
840 Many arch Makefiles dynamically run the target C compiler to 843 Many arch Makefiles dynamically run the target C compiler to
841 probe supported options: 844 probe supported options:
@@ -847,7 +850,7 @@ When kbuild executes, the following steps are followed (roughly):
847 -march=pentium2,-march=i686) 850 -march=pentium2,-march=i686)
848 ... 851 ...
849 # Disable unit-at-a-time mode ... 852 # Disable unit-at-a-time mode ...
850 CFLAGS += $(call cc-option,-fno-unit-at-a-time) 853 KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time)
851 ... 854 ...
852 855
853 856