Refine reporting of DPDK-related build messages.

As far as the two current build systems go, most optional modules print
a one-line message to stdout if the user did not specifically request
enabling the module and the module could not be detected automatically.
DPDK in this case prints a multi-line message to stderr, which draws
attention from more severe problems.

Make this behaviour consistent with other modules, also make sure that
in all cases the output indicates whether pkg-config was used, and what
the final outcome of the process is.  While at it, remove the QUIET
option from pkg-config detection to make it easier to understand why
pkg-config was used (or not).

Author: infrastation

CMakeLists.txt

@@ -2049,7 +2049,7 @@ pcap and pcapng files, run cmake with -DPCAP_TYPE=null.")
 endif(WIN32)
 message(STATUS "Packet capture mechanism type: ${PCAP_TYPE}")
 
-find_package(PkgConfig QUIET)
+find_package(PkgConfig)
 
 #
 # Do capture-mechanism-dependent tests.
@@ -2476,12 +2476,18 @@ if(NOT DISABLE_DPDK)
             set(CMAKE_EXTRA_INCLUDE_FILES rte_ether.h)
             check_type_size("struct rte_ether_addr" STRUCT_RTE_ETHER_ADDR)
             cmake_pop_check_state()
+
+            #
+            # Same as in Autoconf.
+            #
+            message(STATUS "building with DPDK")
+        else()
+            #
+            # Same as in Autoconf.
+            #
+            message(STATUS "building without DPDK (present, but cannot be used)")
         endif()
-    else()
-      message(WARNING,
-"We couldn't find DPDK with pkg-config.  If you want DPDK support,
-make sure that pkg-config is installed, that DPDK 18.02.2 or later is
-installed, and that DPDK provides a .pc file.")
+    # Else: Finddpdk.cmake has already printed the diagnostics.
     endif()
 endif()
 

cmake/Modules/Finddpdk.cmake

@@ -32,6 +32,17 @@
 # to PKG_CONFIG_PATH, so we look for the .pc file there,
 # first.
 #
+
+#
+# If pkg-config is not available; the last line of the output is:
+# "-- Could NOT find dpdk (missing: dpdk_INCLUDE_DIRS dpdk_LIBRARIES)"
+# More than 20 lines before that there is the root cause:
+# "-- Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE)"
+# Print a message to make the cause and the effect easier to relate,
+# whether the attempt fails or not.
+#
+message(STATUS "Using pkg-config to find DPDK: ${PKG_CONFIG_FOUND}")
+
 if(PKG_CONFIG_FOUND)
   set(save_PKG_CONFIG_PATH $ENV{PKG_CONFIG_PATH})
   if(dpdk_ROOT)

configure.ac

@@ -2620,13 +2620,19 @@ if test "$want_dpdk" != no; then
 		if test $V_PCAP != dpdk ; then
 			MODULE_C_SRC="$MODULE_C_SRC pcap-dpdk.c"
 		fi
+
+		#
+		# The last line of the output is:
+		# "checking for struct rte_ether_addr... yes"
+		# Make it clear what it means for the final result.
+		#
+		AC_MSG_NOTICE([building with DPDK])
 	else
 		#
 		# We didn't find a usable DPDK.
 		# If we required it (with --with-dpdk or --with-pcap=dpdk),
 		# fail with an appropriate message telling the user what
-		# the problem was, otherwise note the problem with a
-		# warning.
+		# the problem was.
 		#
 		if test "$found_dpdk" != yes; then
 			#
@@ -2659,13 +2665,13 @@ DPDK provides .pc file.])
 
 			#
 			# User didn't indicate whether they wanted DPDK
-			# or not; just warn why we didn't find it.
+			# or not; the last line of the output is one of:
+			# "checking for libdpdk with pkg-config... pkg-config not found"
+			# "checking for libdpdk with pkg-config... not found"
+			# This conveys the point and is the right amount of
+			# output when auto-detecting an optional module, so do
+			# not print anything else.
 			#
-			AC_MSG_WARN(
-[We couldn't find DPDK with pkg-config.  If
-you want DPDK support, make sure that pkg-config is installed,
-that DPDK 18.02.2 or later is installed, and that DPDK provides a
-.pc file.])
 		elif test "$ac_cv_func_rte_eth_dev_count_avail" != yes; then
 			#
 			# Found with pkg-config, but we couldn't compile
@@ -2698,11 +2704,11 @@ or later is DPDK is installed.])
 
 			#
 			# User didn't indicate whether they wanted DPDK
-			# or not; just warn why we didn't find it.
+			# or not; the last line of the output is:
+			# "checking for rte_eth_dev_count_avail... no"
+			# Make it clear what it means for the final result.
 			#
-			AC_MSG_WARN(
-[DPDK was found, but we can't compile libpcap with it.
-Make sure that DPDK 18.02.2 or later is installed.])
+			AC_MSG_NOTICE([building without DPDK (present, but cannot be used)])
 		fi
 	fi
 fi