kbuild: Add "make help" support

Added the new target "help" that list the most common targets
Calls down to Documentation/Makefile to list documentation targets.
Furthermore calls down to the architecture specific Makefile
to list architecture specific targets.
So far only i386 is supporting this.

Documentation/DocBook/Makefile

@@ -15,6 +15,10 @@ C-procfs-example = procfs_example.sgml
 $(TOPDIR)/scripts/docgen $(TOPDIR)/scripts/gen-all-syms \
 $(TOPDIR)/scripts/kernel-doc $(TOPDIR)/scripts/docproc: doc-progs ;
 
+dochelp:
+	@echo  '  Linux kernel internal documentation in different formats:'
+	@echo  '  sgmldocs (SGML), psdocs (Postscript), pdfdocs (PDF), htmldocs (HTML)'
+
 .PHONY: doc-progs
 doc-progs:
 	@$(MAKE) -C $(TOPDIR)/scripts doc-progs

Makefile

@@ -3,6 +3,12 @@ PATCHLEVEL = 5
 SUBLEVEL = 23
 EXTRAVERSION =
 
+# *DOCUMENTATION*
+# Too see a list of typical targets execute "make help"
+# More info can be located in ./Documentation/kbuild
+# Comments in this file is targeted only to the developer, do not
+# expect to learn how to build the kernel reading this file.
+
 # We are using a recursive build, so we need to do a little thinking
 # to get the ordering right.
 #
@@ -156,7 +162,7 @@ SUBDIRS		:= init kernel mm fs ipc lib drivers sound net
 noconfig_targets := xconfig menuconfig config oldconfig randconfig \
 		    defconfig allyesconfig allnoconfig allmodconfig \
 		    clean mrproper distclean \
-		    tags TAGS sgmldocs psdocs pdfdocs htmldocs \
+		    help tags TAGS sgmldocs psdocs pdfdocs htmldocs \
 		    checkconfig checkhelp checkincludes
 
 ifeq ($(filter $(noconfig_targets),$(MAKECMDGOALS)),)
@@ -673,6 +679,43 @@ tags: FORCE
 	find include -type d \( -name "asm-*" -o -name config \) -prune -o -name '*.h' -print | xargs ctags $$CTAGSF -a && \
 	find $(SUBDIRS) init -name '*.[ch]' | xargs ctags $$CTAGSF -a
 
+# Brief documentation of the typical targets used
+# ---------------------------------------------------------------------------
+
+help:
+	@echo  'Cleaning targets:'
+	@echo  '  clean		- remove most generated files but keep the config'
+	@echo  '  mrproper	- remove all generated files including the config'
+	@echo  '  distclean	- mrproper + remove files generated by editors and patch'
+	@echo  ''
+	@echo  'Configuration targets:'
+	@echo  '  oldconfig	- Update current config utilising a line-oriented program'
+	@echo  '  menuconfig	- Update current config utilising a menu based program'
+	@echo  '  xconfig	- Update current config utilising a X-based program'
+	@echo  '  defconfig	- New config with default answer to all options'
+	@echo  '  allmodconfig	- New config selecting modules when possible'
+	@echo  '  allyesconfig	- New config where all options are accepted with yes'
+	@echo  '  allnoconfig	- New minimal config'
+	@echo  ''
+	@echo  'Other generic targets:'
+	@echo  '  all		- Build all targets marked with [*]'
+	@echo  '  dep           - Create module version information'
+	@echo  '* vmlinux	- Build the bare kernel'
+	@echo  '* modules	- Build all modules'
+	@echo  '  dir/file.[ois]- Build specified target only'
+	@echo  '  rpm		- Build a kernel as an RPM package'
+	@echo  '  tags/TAGS	- Generate tags file for editors'
+	@echo  ''
+	@echo  'Documentation targets:'
+	@$(MAKE) --no-print-directory -f Documentation/DocBook/Makefile dochelp
+	@echo  ''
+	@echo  'Architecture specific targets ($(ARCH)):'
+	@$(MAKE) --no-print-directory -f arch/$(ARCH)/boot/Makefile archhelp
+	@echo  ''
+	@echo  'Execute "make" or "make all" to build all targets marked with [*] '
+	@echo  'For further info browse Documentation/kbuild/*'
+ 
+
 # Documentation targets
 # ---------------------------------------------------------------------------
 

arch/i386/boot/Makefile

@@ -30,6 +30,10 @@ EXTRA_TARGETS	:= vmlinux.bin bvmlinux.bin bootsect bootsect.o \
 
 host-progs	:= tools/build
 
+# 	Default
+
+boot: bzImage
+
 include $(TOPDIR)/Rules.make
 
 # ---------------------------------------------------------------------------
@@ -79,3 +83,11 @@ clean:
 	@rm -f setup bootsect zImage compressed/vmlinux.out
 	@rm -f bsetup bbootsect bzImage compressed/bvmlinux.out
 	@$(MAKE) -C compressed clean
+
+archhelp:
+	@echo  '* bzImage	- Compressed kernel image (arch/$(ARCH)/boot/bzImage)'
+	@echo  '  install	- Install kernel using'
+	@echo  '                  (your) ~/bin/installkernel or'
+	@echo  '                  (distribution) /sbin/installkernel or'
+	@echo  '        	  install to $$(INSTALL_PATH) and run lilo'
+