diff --git a/Pmodules/libpbuild.bash b/Pmodules/libpbuild.bash
index f2ff936..cdcdb66 100644
--- a/Pmodules/libpbuild.bash
+++ b/Pmodules/libpbuild.bash
@@ -79,7 +79,7 @@ pbuild::add_to_group() {
 # $@: dependencies
 #
 pbuild::set_build_dependencies() {
-	MODULE_BUILD_DEPENDENCIES=("$@")
+	MODULE_BUILD_DEPENDENCIES+=("$@")
 }
 
 pbuild::set_runtime_dependencies() {
@@ -164,7 +164,19 @@ pbuild::configure() {
 }
 
 pbuild::build() {
-	make -j${JOBS}
+	# :FIXME:
+	# the clang based assembler in Xcode 7 is broken:
+	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66509
+	# for the time being we have to use some bin's from MacPorts 
+	case ${OS} in
+	Darwin )
+		#PATH="/opt/local/bin:$PATH"
+		make -j${JOBS}
+		;;
+	* )
+		make -j${JOBS}
+		;;
+	esac
 }
 
 pbuild::install() {
@@ -247,17 +259,28 @@ pbuild::make_all() {
 
 	##############################################################################
 	#
+	# build dependencies can be defined
+	# - on the command line via '--with=MODULE/VERSION'
+	# - in a 'variants' file
+	# - in the build block
+	#
 	load_build_dependencies() {
-		for m in "${MODULE_BUILD_DEPENDENCIES[@]}"; do
+		
+		declare variants=''
+		if [[ -r "${BUILD_BLOCK_DIR}/${V}/variants" ]]; then
+			variants="${BUILD_BLOCK_DIR}/${V}/variants"
+		elif [[ -r "${BUILD_BLOCK_DIR}/${V%.*}/variants" ]]; then
+			variants="${BUILD_BLOCK_DIR}/${V%.*}/variants"
+		elif [[ -r "${BUILD_BLOCK_DIR}/${V%.*.*}/variants" ]]; then
+			variants="${BUILD_BLOCK_DIR}/${V%.*.*}/variants"
+		fi
+		if [[ -n "${variants}" ]]; then
+		        with_modules+=( $(egrep "$V\s.*${OS}" "${variants}" | tail -1 |
+				 awk "${with_modules_awk_pattern} {for (i=4; i<=NF; i++) printf \$i \" \"}") )
+		fi
+
+		for m in "${with_modules[@]}" "${MODULE_BUILD_DEPENDENCIES[@]}"; do
 			[[ -z $m ]] && continue
-			if [[ ! $m =~ "*/*" ]]; then
-				local _V=$(echo -n $m | tr [:lower:] [:upper:] )_VERSION
-				if [[ -n ${!_V} ]]; then
-		    			m=$m/${!_V}
-				else
-					echo "$m: warning: No version set, loading default ..."
-				fi
-			fi
 			is_loaded "$m" && continue
 			if ! pbuild::module_is_available "$m"; then
 				std::debug "${m}: module not available"
@@ -305,22 +328,20 @@ pbuild::make_all() {
 					std::die 1 "$m: oops: build failed..."
 				fi
 			fi
-			# :FIXME: this doesn't work any more!
-			local modulepath_root="${PMODULES_ROOT}/${PMODULES_MODULEFILES_DIR}"
-			local tmp=$( module display "${m}" 2>&1 | grep -m1 -- "${modulepath_root}" )
-			tmp=${tmp/${modulepath_root}\/}
-			tmp=${tmp%%/*}
-			local _family=( ${tmp//./ } )
-			if [[ ${_family[1]} == deprecated ]]; then
+
+			local mod_name=''
+			local mod_release=''
+			read mod_name mod_release < <("${MODULECMD}" bash avail -a -m $m 2>&1 1>/dev/null | tail -1)
+
+			if [[ ${mod_release} == deprecated ]]; then
 				# set module release to 'deprecated' if a build dependency
 				# is deprecated
 				DEPEND_RELEASE='deprecated'
-			elif [[ ${_family[1]} == unstable ]] && [[ -z ${DEPEND_RELEASE} ]]; then
+			elif [[ ${mod_release} == unstable ]] && [[ -z ${DEPEND_RELEASE} ]]; then
 				# set module release to 'unstable' if a build dependency is
 				# unstable and release not yet set
 				DEPEND_RELEASE='unstable'
 			fi
-
 			
 			echo "Loading module: ${m}"
 			module load "${m}"
@@ -476,7 +497,7 @@ pbuild::make_all() {
 		# set PREFIX of module
 		PREFIX="${PMODULES_ROOT}/${MODULE_GROUP}/${MODULE_RPREFIX}"
 
-		# get module release if already installed
+		# get module release if already available
 		local saved_modulepath=${MODULEPATH}
 		rels=( ${releases//:/ } )
 		for rel in "${rels[@]}"; do
@@ -497,7 +518,7 @@ pbuild::make_all() {
 		#   - if a build-dependency is deprecated or 
 		#   - the module already exists and is deprecated or
 		#   - is forced to be deprecated by setting this on the command line
-		if [[ "${depend_release}" == 'deprecated' ]] || \
+		if [[ "${DEPEND_RELEASE}" == 'deprecated' ]] || \
 		       [[ "${cur_module_release}" == 'deprecated' ]] \
 		       || [[ "${MODULE_RELEASE}" == 'deprecated' ]]; then
 			MODULE_RELEASE='deprecated'
@@ -508,7 +529,7 @@ pbuild::make_all() {
 			#   - the module already exists and is stable
 			#   - an unstable release of the module exists and the release is
 			#     changed to stable on the command line
-		elif [[ "${depend_release}" == 'stable' ]] \
+		elif [[ "${DEPEND_RELEASE}" == 'stable' ]] \
 			 || [[ "${cur_module_release}" == 'stable' ]] \
 			 || [[ "${MODULE_RELEASE}" == 'stable' ]]; then
 			MODULE_RELEASE='stable'
diff --git a/Pmodules/modbuild b/Pmodules/modbuild
index 1185baa..373e22b 100755
--- a/Pmodules/modbuild
+++ b/Pmodules/modbuild
@@ -154,9 +154,6 @@ if (( ok != 0 )); then
 	exit 1
 fi
 
-# :FIXME: move to library?
-declare -r OS=$(uname -s)
-
 ##############################################################################
 #
 # parse arguments
@@ -284,6 +281,15 @@ fi
 [[ -n ${BUILD_BLOCK} ]] || std::die 1 "No build-block specified!"
 [[ -r ${BUILD_BLOCK} ]] || std::die 1 "${BUILD_BLOCK}: no such file!"
 
+# :FIXME: move to library?
+declare -r OS=$(uname -s)
+case ${OS} in
+Darwin )
+	declare -rx MACOSX_DEPLOYMENT_TARGET='10.9'
+	#declare -rx SDKROOT='macosx10.9'
+	;;
+esac
+
 
 # source Pmodule environment configuration
 if [[ "${bootstrap}" == "yes" ]]; then
@@ -321,38 +327,21 @@ for dir in "${bash_libpath[@]}"; do
 done
 (( ok == 0 )) || std::die 3 "Oops: required BASH library '${libpbuild}' not found"
 
-# load all modules passed via the '--with' argument or specified in a
-# configuration file.
-# :FIXME:
-#	It should be possible to overwrite dependencies given in the
-#	configuration file(s) via the '--with=something' argument. For
-#	the time being we do not check anything - we just try to load
-#	everything, even if a module of different version has already
-#	been load.
-# :FIXME:
-#	Specifying dependencies via 'with_modules' is deprecated and
-#	should be removed.
 if [[ ${bootstrap} == no ]]; then
 	# we aren't bootstraping
 
-	declare variants=''
-	if [[ -r "${BUILD_BLOCK_DIR}/${V}/variants" ]]; then
-		variants="${BUILD_BLOCK_DIR}/${V}/variants"
-	elif [[ -r "${BUILD_BLOCK_DIR}/${V%.*}/variants" ]]; then
-		variants="${BUILD_BLOCK_DIR}/${V%.*}/variants"
-	elif [[ -r "${BUILD_BLOCK_DIR}/${V%.*.*}/variants" ]]; then
-		variants="${BUILD_BLOCK_DIR}/${V%.*.*}/variants"
-	fi
-	if [[ -n "${variants}" ]]; then
-	        with_modules+=( $(egrep "$V\s.*${OS}" "${variants}" |
-			 awk "${with_modules_awk_pattern} {for (i=4; i<=NF; i++) printf \$i \" \"}" | tail -1) )
-	else
-		if [[ -r "${BUILD_BLOCK_DIR}/with_modules-$V" ]]; then
-			with_modules+=( $(cat "${BUILD_BLOCK_DIR}/with_modules-$V") )
-		elif [[ -r "${BUILD_BLOCK_DIR}/with_modules" ]]; then
-			with_modules+=( $(cat "${BUILD_BLOCK_DIR}/with_modules") )
-		fi
-	fi
+	#declare variants=''
+	#if [[ -r "${BUILD_BLOCK_DIR}/${V}/variants" ]]; then
+	#	variants="${BUILD_BLOCK_DIR}/${V}/variants"
+	#elif [[ -r "${BUILD_BLOCK_DIR}/${V%.*}/variants" ]]; then
+	#	variants="${BUILD_BLOCK_DIR}/${V%.*}/variants"
+	#elif [[ -r "${BUILD_BLOCK_DIR}/${V%.*.*}/variants" ]]; then
+	#	variants="${BUILD_BLOCK_DIR}/${V%.*.*}/variants"
+	#fi
+	#if [[ -n "${variants}" ]]; then
+	#        with_modules+=( $(egrep "$V\s.*${OS}" "${variants}" | tail -1 |
+	#		 awk "${with_modules_awk_pattern} {for (i=4; i<=NF; i++) printf \$i \" \"}") )
+	#fi
 
         source	"${PMODULES_ROOT}/${PMODULES_CONFIG_DIR}/profile.bash"
 	MODULECMD="${PMODULES_HOME}/bin/modulecmd"
@@ -369,14 +358,6 @@ if [[ ${bootstrap} == no ]]; then
 	eval $( "${MODULECMD}" bash use unstable )
 	eval $( "${MODULECMD}" bash use deprecated )
 	eval $( "${MODULECMD}" bash use Libraries )
-	for m in "${with_modules[@]}"; do
-		if pbuild::module_is_available "$m"; then
-			echo "Loading module: ${m}"
-			module load "${m}"
-		else
-			std::die 44 "$m: module not available!"
-		fi
-	done
 else
 	#  the module command is not yet available...
 	pbuild::cleanup_env
diff --git a/Pmodules/modulecmd.bash.in b/Pmodules/modulecmd.bash.in
index 6968005..56f3bcf 100755
--- a/Pmodules/modulecmd.bash.in
+++ b/Pmodules/modulecmd.bash.in
@@ -200,7 +200,7 @@ subcommand_help_keyword() {
 subcommand_help_avail() {
 	echo "
 USAGE:
-        module avail string
+        module avail [switches] string
 		List all available modulefiles in the current MODULEPATH. If
 		an argument is given, then each directory in the MODULEPATH
 		is searched for modulefiles whose pathname match the argument.
@@ -209,6 +209,21 @@ USAGE:
 		system. Only *loadable* modules are listed.  The list of 
 		available modules may change either by loading other modules,
 		e.g. a compiler, or with the sub-command 'use'.
+
+SWITCHES:
+        -a|--all||--all-releases
+		List all available modules independend of the release.
+		
+	-t|--terse
+		Output in short format.
+
+	-l|--long
+		Output in long format.
+
+	-h|--human
+		Output in human readable format.
+	-m|--machine
+		Output in machine readable format
 " 1>&2
 	std::die 1
 }
@@ -971,6 +986,12 @@ subcommand_avail() {
 		std::info ""
 	}
 
+	machine_output() {
+		for (( i=0; i<${#mods[@]}; i+=2 )); do
+			printf "%-20s\t%s\n" "${mods[i]}" "${mods[i+1]}" 1>&2
+		done
+	}
+
 	#
 	# :FIXME: for the time being, this is the same as terse_output!
 	long_output() {
@@ -1028,13 +1049,19 @@ subcommand_avail() {
 		printf -- "\n\n" 1>&2
 	}
 	local opts=''
-	opts=$(pmodules::get_options -o hlt -l human -l long -l terse -- "$@") || subcommand_help_avail
+	opts=$(pmodules::get_options -o ahlmt \
+			-l all -l all-releases \
+			-l human -l long -l machine -l terse -- "$@") || subcommand_help_avail
 	eval set --  "${opts}"
 	local pattern=()
 	local output_function=''
 	local opts=''
+	local use_releases="${UsedReleases}"
 	while (($# > 0)); do
 		case $1 in
+			-a | --all | --all-releases )
+				use_releases="${PMODULES_DEFINED_RELEASES}"
+				;;
 			-h | --human )
 				[[ -z ${opts} ]] || \
 				    std::die 1 "${CMD} list: you cannot set both options: '$1' and '${opts}'."
@@ -1053,6 +1080,12 @@ subcommand_avail() {
 				opts=$1
 				output_function='terse_output'
 				;;
+			-m | --machine )
+				[[ -z ${opts} ]] || \
+				    std::die 1 "${CMD} list: you cannot set both options: '$1' and '${opts}'."
+				opts=$1
+				output_function='machine_output'
+				;;
 			-- )
 				;;
 			* )
@@ -1071,7 +1104,7 @@ subcommand_avail() {
 	IFS=${saved_IFS}
 	for string in "${pattern[@]}"; do
 		for dir in "${modulepath[@]}"; do
-			mods=( $( get_available_modules "${dir}" "${string}" ) )
+			mods=( $( get_available_modules "${dir}" "${string}" "${use_releases}" ) )
 			[[ ${#mods[@]} == 0 ]] && continue
 
 			${output_function}