Commit 4a5838ad authored by Borislav Petkov's avatar Borislav Petkov Committed by Michal Marek
Browse files

kbuild: Add extra gcc checks 

Add a 'W=1' Makefile switch which adds additional checking per build
object.

The idea behind this option is targeted at developers who, in the
process of writing their code, want to do the occasional

make W=1 [target.o]

and let gcc do more extensive code checking for them. Then, they
could eyeball the output for valid gcc warnings about various
bugs/discrepancies which are not reported during the normal build
process.

For more background information and a use case, read through this
thread: http://marc.info/?l=kernel-janitors&m=129802065918147&w=2



Cc: Michal Marek <mmarek@suse.cz>
Cc: linux-kbuild@vger.kernel.org
Acked-by: default avatarSam Ravnborg <sam@ravnborg.org>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarBorislav Petkov <bp@alien8.de>
Signed-off-by: default avatarMichal Marek <mmarek@suse.cz>
parent de933bd8

Documentation/kbuild/kbuild.txt

+5 −0
Original line number Diff line number Diff line
@@ -196,3 +196,8 @@ to be included in the databases, separated by blank space. E.g.: 
To get all available archs you can also specify all. E.g.:



    $ make ALLSOURCE_ARCHS=all tags



KBUILD_ENABLE_EXTRA_GCC_CHECKS

--------------------------------------------------

If enabled over the make command line with "W=1", it turns on additional

gcc -W... options for more extensive build-time checking.

Makefile

+5 −0
Original line number Diff line number Diff line
@@ -102,6 +102,10 @@ ifeq ("$(origin O)", "command line") 
  KBUILD_OUTPUT := $(O)

endif



ifeq ("$(origin W)", "command line")

  export KBUILD_ENABLE_EXTRA_GCC_CHECKS := 1

endif



# That's our default target when none is given on the command line

PHONY := _all

_all:
@@ -1262,6 +1266,7 @@ 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  ''

	@echo  'Execute "make" or "make all" to build all targets marked with [*] '

	@echo  'For further info see the ./README file'

scripts/Makefile.build

+34 −1
Original line number Diff line number Diff line
@@ -49,6 +49,40 @@ ifeq ($(KBUILD_NOPEDANTIC),) 
                $(error CFLAGS was changed in "$(kbuild-file)". Fix it to use EXTRA_CFLAGS)

        endif

endif



#

# make W=1 settings

#

# $(call cc-option... ) 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)

endif



include scripts/Makefile.lib



ifdef host-progs
@@ -403,7 +437,6 @@ ifneq ($(cmd_files),) 
  include $(cmd_files)

endif





# Declare the contents of the .PHONY variable as phony.  We keep that

# information in a variable se we can use it in if_changed and friends.

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