3 files changed, 44 insertions, 1 deletions

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 4a990317b84a..376538c984ce 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -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.
diff --git a/Makefile b/Makefile
index abb49bf8596e..2b1e37da2bb5 100644
--- a/Makefile
+++ b/Makefile
@@ -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'
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 4eb99ab34053..d5f925abe4d2 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -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.