Re: [PATCH v3.1] kbuild: implement several W= levels

[Michal Marek <mmarek@suse.cz>]

On 22.4.2011 19:50, Borislav Petkov wrote:
> From: Sam Ravnborg <sam@ravnborg.org>
> 
> Building a kernel with "make W=1" produce far too much noise
> to be usefull.
> 
> Divide the warning options in three groups:
> 
>     W=1 - warnings that may be relevant and does not occur too often
>     W=2 - warnings that occur quite often but may still be relevant
>     W=3 - the more obscure warnings, can most likely be ignored
> 
> When building init/ on my box the levels produces:
> 
> W=1 - 46 warnings
> W=2 - 863 warnings
> W=3 - 6496 warnings

I guess these numbers are not valid after your changes? Not that the
exact numbers are important, but maybe the distribution change?
Otherwise the patch looks good, thanks a lot to both of you!

Michal
> 
> Many warnings occur from .h files so fixing one file may have a nice
> effect on the total number of warnings.
> 
> With these changes I am actually tempted to try W=1 now and then.
> Previously there were just too much noise.
> 
> Borislav:
> 
> - make the W= levels exclusive
> - move very noisy and making little sense for the kernel warnings to W=3
> - drop -Woverlength-strings due to useless warning message
> - copy explanatory text for the different warning levels to 'make help'
> 
> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> Signed-off-by: Borislav Petkov <bp@alien8.de>
> Cc: Dave Jones <davej@redhat.com>
> ---
>  Makefile               |    8 ++++-
>  scripts/Makefile.build |   65 ++++++++++++++++++++++++++++--------------------
>  2 files changed, 44 insertions(+), 29 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index b967b96..17ce5d5 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -103,7 +103,7 @@ ifeq ("$(origin O)", "command line")
>  endif
>  
>  ifeq ("$(origin W)", "command line")
> -  export KBUILD_ENABLE_EXTRA_GCC_CHECKS := 1
> +  export KBUILD_ENABLE_EXTRA_GCC_CHECKS := $(W)
>  endif
>  
>  # That's our default target when none is given on the command line
> @@ -1267,7 +1267,11 @@ help:
>  	@echo  '  make O=dir [targets] Locate all output files in "dir", including .config'
>  	@echo  '  make C=1   [targets] Check all c source with $$CHECK (sparse by default)'
>  	@echo  '  make C=2   [targets] Force check of all c source with $$CHECK'
> -	@echo  '  make W=1   [targets] Enable extra gcc checks'
> +	@echo  '  make W=n   [targets] Enable extra gcc checks, n=1,2,3 where'
> +	@echo  '		1: warnings which may be relevant and do not occur too often'
> +	@echo  '		2: warnings which occur quite often but may still be relevant'
> +	@echo  '		3: more obscure warnings, can most likely be ignored'
> +
>  	@echo  ''
>  	@echo  'Execute "make" or "make all" to build all targets marked with [*] '
>  	@echo  'For further info see the ./README file'
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index d5f925a..ffb383c 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -51,36 +51,47 @@ ifeq ($(KBUILD_NOPEDANTIC),)
>  endif
>  
>  #
> -# make W=1 settings
> +# make W=... settings
>  #
> -# $(call cc-option... ) handles gcc -W.. options which
> +# W=1 - warnings that may be relevant and does not occur too often
> +# W=2 - warnings that occur quite often but may still be relevant
> +# W=3 - the more obscure warnings, can most likely be ignored
> +#
> +# $(call cc-option, -W...) handles gcc -W.. options which
>  # are not supported by all versions of the compiler
>  ifdef KBUILD_ENABLE_EXTRA_GCC_CHECKS
> -KBUILD_EXTRA_WARNINGS := -Wextra
> -KBUILD_EXTRA_WARNINGS += -Wunused -Wno-unused-parameter
> -KBUILD_EXTRA_WARNINGS += -Waggregate-return
> -KBUILD_EXTRA_WARNINGS += -Wbad-function-cast
> -KBUILD_EXTRA_WARNINGS += -Wcast-qual
> -KBUILD_EXTRA_WARNINGS += -Wcast-align
> -KBUILD_EXTRA_WARNINGS += -Wconversion
> -KBUILD_EXTRA_WARNINGS += -Wdisabled-optimization
> -KBUILD_EXTRA_WARNINGS += -Wlogical-op
> -KBUILD_EXTRA_WARNINGS += -Wmissing-declarations
> -KBUILD_EXTRA_WARNINGS += -Wmissing-format-attribute
> -KBUILD_EXTRA_WARNINGS += $(call cc-option, -Wmissing-include-dirs,)
> -KBUILD_EXTRA_WARNINGS += -Wmissing-prototypes
> -KBUILD_EXTRA_WARNINGS += -Wnested-externs
> -KBUILD_EXTRA_WARNINGS += -Wold-style-definition
> -KBUILD_EXTRA_WARNINGS += $(call cc-option, -Woverlength-strings,)
> -KBUILD_EXTRA_WARNINGS += -Wpacked
> -KBUILD_EXTRA_WARNINGS += -Wpacked-bitfield-compat
> -KBUILD_EXTRA_WARNINGS += -Wpadded
> -KBUILD_EXTRA_WARNINGS += -Wpointer-arith
> -KBUILD_EXTRA_WARNINGS += -Wredundant-decls
> -KBUILD_EXTRA_WARNINGS += -Wshadow
> -KBUILD_EXTRA_WARNINGS += -Wswitch-default
> -KBUILD_EXTRA_WARNINGS += $(call cc-option, -Wvla,)
> -KBUILD_CFLAGS += $(KBUILD_EXTRA_WARNINGS)
> +warning-1 := -Wextra -Wunused -Wno-unused-parameter
> +warning-1 += -Wmissing-declarations
> +warning-1 += -Wmissing-format-attribute
> +warning-1 += -Wmissing-prototypes
> +warning-1 += -Wold-style-definition
> +warning-1 += $(call cc-option, -Wmissing-include-dirs)
> +
> +warning-2 := -Waggregate-return
> +warning-2 += -Wcast-align
> +warning-2 += -Wdisabled-optimization
> +warning-2 += -Wnested-externs
> +warning-2 += -Wshadow
> +warning-2 += $(call cc-option, -Wlogical-op)
> +
> +warning-3 := -Wbad-function-cast
> +warning-3 += -Wcast-qual
> +warning-3 += -Wconversion
> +warning-3 += -Wpacked
> +warning-3 += -Wpadded
> +warning-3 += -Wpointer-arith
> +warning-3 += -Wredundant-decls
> +warning-3 += -Wswitch-default
> +warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
> +warning-3 += $(call cc-option, -Wvla)
> +
> +warning := $(warning-$(KBUILD_ENABLE_EXTRA_GCC_CHECKS))
> +
> +ifeq ("$(warning)","")
> +        $(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
> +endif
> +
> +KBUILD_CFLAGS += $(warning)
>  endif
>  
>  include scripts/Makefile.lib