docsrc: build Documentation/ sources

Currently source files in the Documentation/ sub-dir can easily bit-rot
since they are not generally buildable, either because they are hidden in
text files or because there are no Makefile rules for them.  This needs to
be fixed so that the source files remain usable and good examples of code
instead of bad examples.

Add the ability to build source files that are in the Documentation/ dir.
Add to Kconfig as "BUILD_DOCSRC" config symbol.

Use "CONFIG_BUILD_DOCSRC=1 make ..." to build objects from the
Documentation/ sources.  Or enable BUILD_DOCSRC in the *config system.
However, this symbol depends on HEADERS_CHECK since the header files need
to be installed (for userspace builds).

Built (using cross-tools) for x86-64, i386, alpha, ia64, sparc32,
sparc64, powerpc, sh, m68k, & mips.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/DocBook/Makefile

@@ -102,6 +102,13 @@ C-procfs-example = procfs_example.xml
 C-procfs-example2 = $(addprefix $(obj)/,$(C-procfs-example))
 $(obj)/procfs-guide.xml: $(C-procfs-example2)
 
+# List of programs to build
+##oops, this is a kernel module::hostprogs-y := procfs_example
+obj-m += procfs_example.o
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
 notfoundtemplate = echo "*** You have to install docbook-utils or xmlto ***"; \
 		   exit 1
 db2xtemplate = db2TYPE -o $(dir $@) $<

Documentation/Makefile

+obj-m := DocBook/ accounting/ auxdisplay/ connector/ \
+	filesystems/configfs/ ia64/ networking/ \
+	pcmcia/ spi/ video4linux/ vm/ watchdog/src/

Documentation/accounting/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := getdelays
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS_getdelays.o += -I$(objtree)/usr/include

Documentation/auxdisplay/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := cfag12864b-example
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS_cfag12864b-example.o += -I$(objtree)/usr/include

Documentation/connector/Makefile

+ifneq ($(CONFIG_CONNECTOR),)
+obj-m += cn_test.o
+endif
+
+# List of programs to build
+hostprogs-y := ucon
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS_ucon.o += -I$(objtree)/usr/include

Documentation/filesystems/configfs/Makefile

+ifneq ($(CONFIG_CONFIGFS_FS),)
+obj-m += configfs_example_explicit.o configfs_example_macros.o
+endif

Documentation/ia64/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := aliasing-test
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)

Documentation/networking/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := ifenslave
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)

Documentation/pcmcia/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := crc32hash
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS_crc32hash.o += -I$(objtree)/usr/include

Documentation/spi/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := spidev_test spidev_fdx
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS_spidev_test.o += -I$(objtree)/usr/include
+HOSTCFLAGS_spidev_fdx.o += -I$(objtree)/usr/include

Documentation/video4linux/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := v4lgrab
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)

Documentation/vm/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := slabinfo
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)

Documentation/watchdog/src/Makefile

+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := watchdog-simple watchdog-test
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)

Makefile

@@ -821,6 +821,9 @@ ifdef CONFIG_HEADERS_CHECK
 endif
 ifdef CONFIG_SAMPLES
 	$(Q)$(MAKE) $(build)=samples
+endif
+ifdef CONFIG_BUILD_DOCSRC
+	$(Q)$(MAKE) $(build)=Documentation
 endif
 	$(call vmlinux-modpost)
 	$(call if_changed_rule,vmlinux__)
@@ -1166,7 +1169,7 @@ MRPROPER_FILES += .config .config.old include/asm .version .old_version \
 #
 clean: rm-dirs  := $(CLEAN_DIRS)
 clean: rm-files := $(CLEAN_FILES)
-clean-dirs      := $(addprefix _clean_,$(srctree) $(vmlinux-alldirs))
+clean-dirs      := $(addprefix _clean_,$(srctree) $(vmlinux-alldirs) Documentation)
 
 PHONY += $(clean-dirs) clean archclean
 $(clean-dirs):

lib/Kconfig.debug

@@ -735,6 +735,15 @@ config FIREWIRE_OHCI_REMOTE_DMA
 
 	  If unsure, say N.
 
+menuconfig BUILD_DOCSRC
+	bool "Build targets in Documentation/ tree"
+	depends on HEADERS_CHECK
+	help
+	  This option attempts to build objects from the source files in the
+	  kernel Documentation/ tree.
+
+	  Say N if you are unsure.
+
 source "samples/Kconfig"
 
 source "lib/Kconfig.kgdb"