Makefiles: new targets to build & install just software or just docs

This is mostly to help the debian packaging build just the
architecture-dependent parts (the software, via `dpkg-buildpackage -B`) or
just the architecture-independent parts (the docs, via `dpkg-buildpackage
-A`).

Author: SebKuzminsky

docs/src/Submakefile

@@ -28,7 +28,7 @@ MAN_SRCS = $(sort \
 	./config.status --file=$@:$<
 
 ifneq ($(MANDB),)
-default: $(DOC_DIR)/man/index.db
+docs: $(DOC_DIR)/man/index.db
 $(DOC_DIR)/man/index.db: $(MAN_SRCS)
 	@echo "Updating 'whatis' database"
 	$(Q)$(MANDB) $(DOC_DIR)/man
@@ -722,7 +722,6 @@ $(patsubst %.adoc,$(DOC_SRCDIR)/%.html,$(DOC_SRCS_ZH_CN_SMALL)): $(DOC_SRCDIR)/%
 		 -a stylesheet=linuxcnc.css \
 		 -d book -a toc -a numbered -b xhtml11 $< || (X=$$?; rm -f $@; exit $$X)
 
-default: docs
 $(DOC_DIR)/html/de/xref.html: objects/xref_de.xml $(DOC_SRCDIR)/xref.xsl $(DOC_SRCDIR)/docs.xml $(DOC_SRCDIR)/terms.xml
 	$(ECHO) Converting $< to HTML
 	@xsltproc --stringparam docname "xref_de" --stringparam language spanish --path objects -o $@ $(DOC_SRCDIR)/xref.xsl $<
@@ -756,7 +755,6 @@ install-doc-pdf:
 install-doc-html:
 	$(DIR) $(DESTDIR)$(docsdir)
 	cp -a $(DOC_DIR)/html $(DESTDIR)$(docsdir)
-install-kernel-indep: install-doc
 
 docclean:
 	-rm -f $(DOC_DIR)/LinuxCNC_Getting_Started.pdf

src/Makefile

@@ -1,3 +1,31 @@
+# Some useful targets:
+#
+#     default (if no make target is specified): Build the software and
+#         the docs (if enabled via configure).
+#
+#     build-software: Build all the realtime and non-realtime software
+#         libraries & executables.
+#
+#     docs: Build all the documentation that's enabled through configure.
+#
+#
+#     install: Install everything (realtime software, non-realtime
+#         software, and docs).
+#
+#     install-software: Install all architecture-specific things (realtime
+#         and non-realtime libraries and executables).
+#
+#     install-docs: Install all enabled documentation into $(DESTDIR).
+#
+
+
+default: build-software
+
+install: install-software install-docs
+
+install-software: install-kernel-dep install-kernel-indep install-menu
+
+
 # buster gcc (Debian 8.3.0-6) emits many warnings
 # use at your own risk
 ifeq ($(origin SUPPRESS_WARNINGS), undefined)
@@ -32,7 +60,7 @@ endif
 
 # Delete the default suffix rules
 .SUFFIXES:
-.PHONY: default userspace modules clean modclean depclean install python pythonclean cscope cscopeclean
+.PHONY: default build-software userspace modules clean modclean depclean install install-software install-docs python pythonclean cscope cscopeclean
 
 # A "trivial build" is one which should not include dependency information
 # either because it should be usable before dependency information can be
@@ -113,7 +141,7 @@ cxx-option = $(shell if $(CXX) $(CXXFLAGS) $(1) -S -o /dev/null -xc++ /dev/null
 ifeq ($(origin KERNELRELEASE),undefined)
 # When KERNELRELEASE is not defined, this is the userspace build.
 # The "modules" target is the gateway to the kernel module build.
-default: userspace modules
+build-software: userspace modules
 ifeq ($(RUN_IN_PLACE),yes)
 ifneq ($(BUILD_SYS),uspace)
 	@if [ -f ../bin/linuxcnc_module_helper ]; then if ! [ `id -u` = 0 -a -O ../bin/linuxcnc_module_helper -a -u ../bin/linuxcnc_module_helper ]; then $(VECHO) "You now need to run 'sudo make setuid' in order to run in place."; fi; fi
@@ -310,7 +338,7 @@ INFILES = \
 $(INFILES): %: %.in config.status
 	@./config.status --file=$@
 
-default: $(INFILES)
+build-software: $(INFILES)
 
 # For each file to be copied to ../include, its location in the source tree
 # is listed here.  Note that due to $(INCLUDE), defined above, the include
@@ -607,7 +635,7 @@ You configured run-in-place, but are trying to install.
 For an installable version, run configure without --enable-run-in-place
 and rebuild
 endef
-install:
+install install-software install-docs:
 	$(error $(ERROR_MESSAGE))
 
 MENUS = ../share/menus/CNC.menu \
@@ -626,13 +654,6 @@ NC_FILES=$(filter-out %/butterfly.ngc,$(call GLOB,../nc_files/*))
 TCL=$(call GLOB,../tcl/*.tcl)
 TCL_BIN=$(call GLOB,../tcl/bin/*.tcl) ../tcl/bin/popimage
 
-install:
-	$(MAKE) install-docs || echo "Ignored."
-	$(MAKE) install-kernel-dep || echo "Ignored."
-	$(MAKE) install-kernel-indep || echo "Ignored."
-	$(MAKE) install-menu
-	$(ECHO) "Installed in DESTDIR='$(DESTDIR)' with prefix $(prefix)"
-
 install-docs:
 	$(DIR) $(DESTDIR)$(docsdir)
 	$(FILE) $(addprefix ../docs/,$(DOCS)) $(DESTDIR)$(docsdir)