diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 71c602d61680..ab8689b94d65 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -502,6 +502,18 @@ more details, with real examples. gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used. Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options + cc-disable-warning + cc-disable-warning checks if gcc supports a given warning and returns + the commandline switch to disable it. This special function is needed, + because gcc 4.4 and later accept any unknown -Wno-* option and only + warn about it if there is another warning in the source file. + + Example: + KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) + + In the above example, -Wno-unused-but-set-variable will be added to + KBUILD_CFLAGS only if gcc really accepts it. + cc-version cc-version returns a numerical version of the $(CC) compiler version. The format is where both are two digits. So for example diff --git a/Makefile b/Makefile index e9fafd059cc1..92da47363333 100644 --- a/Makefile +++ b/Makefile @@ -549,7 +549,7 @@ endif # This warning generated too much noise in a regular build. # Use make W=1 to enable this warning (see scripts/Makefile.build) -KBUILD_CFLAGS += $(call cc-option, -Wno-unused-but-set-variable) +KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls @@ -579,7 +579,7 @@ CHECKFLAGS += $(NOSTDINC_FLAGS) KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,) # disable pointer signed / unsigned warnings in gcc 4.0 -KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,) +KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign) # disable invalid "can't wrap" optimizations for signed / pointers KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow) diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index ed2773edfe71..ba25c440f9f6 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -118,6 +118,11 @@ cc-option-yn = $(call try-run,\ cc-option-align = $(subst -functions=0,,\ $(call cc-option,-falign-functions=0,-malign-functions=0)) +# cc-disable-warning +# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable) +cc-disable-warning = $(call try-run,\ + $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -xc /dev/null -o "$$TMP",-Wno-$(strip $(1))) + # cc-version # Usage gcc-ver := $(call cc-version) cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))