mk: add "make examples" target in root makefile

It is now possible to build all projects from the examples/ directory
using one command from root directory.

Some illustration of what is possible:

- build examples in the DPDK tree for one target

  # install the x86_64-default-linuxapp-gcc in
  # ${RTE_SDK}/x86_64-default-linuxapp-gcc directory
  user@droids:~/dpdk.org$ make install T=x86_64-default-linuxapp-gcc
  # build examples for this new installation in
  # ${RTE_SDK}/examples directory
  user@droids:~/dpdk.org$ make examples T=x86_64-default-linuxapp-gcc

- build examples outside DPDK tree for several targets

  # install all targets matching x86_64-*-linuxapp-gcc in
  # ${RTE_SDK}/x86_64-*-linuxapp-gcc directories
  user@droids:~/dpdk.org$ make install T=x86_64-*-linuxapp-gcc
  # build examples for these installations in /tmp/foobar
  user@droids:~/dpdk.org$ make examples T=x86_64-*-linuxapp-gcc O=/tmp/foobar

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>

doc/build-sdk-quick.txt

@@ -1,12 +1,14 @@
 Basic build
 	make config T=x86_64-default-linuxapp-gcc && make
 Build commands
-	config      get configuration from target template (T=)
-	all         same as build (default rule)
-	build       build in a configured directory
-	clean       remove files but keep configuration
-	install     build many targets (wildcard allowed) and install in DESTDIR
-	uninstall   remove all installed targets
+	config           get configuration from target template (T=)
+	all              same as build (default rule)
+	build            build in a configured directory
+	clean            remove files but keep configuration
+	install          build many targets (wildcard allowed) and install in DESTDIR
+	uninstall        remove all installed targets
+	examples         build examples for given targets (T=)
+	examples_clean   clean examples for given targets (T=)
 Build variables
 	EXTRA_CPPFLAGS   preprocessor options
 	EXTRA_CFLAGS     compiler options

mk/rte.sdkexamples.mk

@@ -0,0 +1,77 @@
+#   BSD LICENSE
+#
+#   Copyright(c) 2014 6WIND S.A.
+#
+#   Redistribution and use in source and binary forms, with or without
+#   modification, are permitted provided that the following conditions
+#   are met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in
+#       the documentation and/or other materials provided with the
+#       distribution.
+#     * Neither the name of 6WIND S.A. nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# examples application are seen as external applications which are
+# not part of SDK.
+BUILDING_RTE_SDK :=
+export BUILDING_RTE_SDK
+
+# Build directory is given with O=
+O ?= $(RTE_SDK)/examples
+
+# Target for which examples should be built.
+T ?= *
+
+# list all available configurations
+EXAMPLES_CONFIGS := $(patsubst $(RTE_SRCDIR)/config/defconfig_%,%,\
+	$(wildcard $(RTE_SRCDIR)/config/defconfig_$(T)))
+EXAMPLES_TARGETS := $(addsuffix _examples,\
+	$(filter-out %~,$(EXAMPLES_CONFIGS)))
+
+.PHONY: examples
+examples: $(EXAMPLES_TARGETS)
+
+%_examples:
+	@echo ================== Build examples for $*
+	$(Q)if [ ! -d "${RTE_SDK}/${*}" ]; then \
+		echo "Target ${*} does not exist in ${RTE_SDK}/${*}." ; \
+		echo -n "Please install DPDK first (make install) or use another " ; \
+		echo "target argument (T=target)." ; \
+		false ; \
+	else \
+		$(MAKE) -C examples O=$(abspath $(O)) RTE_TARGET=$(*); \
+	fi
+
+EXAMPLES_CLEAN_TARGETS := $(addsuffix _examples_clean,\
+	$(filter-out %~,$(EXAMPLES_CONFIGS)))
+
+.PHONY: examples_clean
+examples_clean: $(EXAMPLES_CLEAN_TARGETS)
+
+%_examples_clean:
+	@echo ================== Clean examples for $*
+	$(Q)if [ ! -d "${RTE_SDK}/${*}" ]; then \
+		echo "Target ${*} does not exist in ${RTE_SDK}/${*}." ; \
+		echo -n "Please install DPDK first (make install) or use another " ; \
+		echo "target argument (T=target)." ; \
+		false ; \
+	else \
+		$(MAKE) -C examples O=$(abspath $(O)) RTE_TARGET=$(*) clean; \
+	fi

mk/rte.sdkroot.mk

@@ -115,6 +115,10 @@ depdirs depgraph:
 gcov gcovclean:
 	$(Q)$(MAKE) -f $(RTE_SDK)/mk/rte.sdkgcov.mk $@
 
+.PHONY: examples examples_clean
+examples examples_clean:
+	$(Q)$(MAKE) -f $(RTE_SDK)/mk/rte.sdkexamples.mk $@
+
 # all other build targets
 %:
 	$(Q)$(MAKE) -f $(RTE_SDK)/mk/rte.sdkconfig.mk checkconfig