--- cdrom	Sun May 06 20:15:10 2018
+++ cdrom	Mon Feb 19 20:35:38 2018
@@ -35,9 +35,6 @@
 	TAR_OPTIONS = --xz
 endif
 
-# Enable multi-threaded compression for LZMA
-export XZ_OPT = --threads=0
-
 ###############################################################################
 # Top-level Rules
 ###############################################################################
--- Config	Sun May 06 20:15:10 2018
+++ Config	Sun Feb 18 14:12:48 2018
@@ -209,7 +209,7 @@
 	tar xf /install/packages/package/files.tmp -C /install/packages/package/tmp/ \
 		-p --numeric-owner
 	rm -f /install/packages/package/files.tmp
-	cd /install/packages/package/tmp/ && XZ_OPT=-T0 tar -c -p --numeric-owner -J -f /install/packages/package/files.tar.xz *
+	cd /install/packages/package/tmp/ && $XZ_OPT tar -c -p --numeric-owner -J -f /install/packages/package/files.tar.xz *
 	rm -r /install/packages/package/tmp
 	-cat /install/packages/package/ROOTFILES | grep -v "#" > /install/packages/package/ROOTFILES.tmp
 	mv /install/packages/package/ROOTFILES.tmp /install/packages/package/ROOTFILES
--- make.sh	Thu May 10 09:53:08 2018
+++ make.sh	Sat May 12 16:03:55 2018
@@ -632,6 +632,10 @@
 
 	local PS1='\u:\w$ '
 
+# XZ-TUNING BEGIN
+	local XZ_OPT='$XZ_OPT'
+# XZ-TUNING END
+
 	enterchroot \
 		${EXTRA_PATH}bash -x -c "cd /usr/src/lfs && \
 			MAKETUNING=${MAKETUNING} \
@@ -653,6 +657,10 @@
 
 	local PS1='\u:\w$ '
 
+# XZ-TUNING BEGIN
+	local XZ_OPT='$XZ_OPT'
+# XZ-TUNING END
+
 	enterchroot \
 		bash -x -c "cd /usr/src/lfs && make -f $* LFS_BASEDIR=/usr/src dist" \
 		>> ${LOGFILE} 2>&1 &
@@ -860,6 +868,38 @@
 # Get the amount of memory in this build system
 HOST_MEM=$(system_memory)
 
+# XZ-TUNING BEGIN
+# Checking host memory
+
+if [ $HOST_MEM -ge 1024 ]; then
+	print_build_stage "Host-Memory: $HOST_MEM MiB"
+	print_build_stage "Host memory is OK (must be at least 1024 MiB), calculating XZ memory..."
+
+# Host memory is ok, calculating XZ memory
+echo
+
+	XZ_MEM="$(( HOST_MEM * 7 / 10 ))MiB"
+	XZ_OPT="--threads=0 -8 $XZ_MEM"
+	print_build_stage "XZ-Memory:" $XZ_MEM
+	print_build_stage "XZ-Options:" $XZ_OPT
+	print_build_stage "XZ memory size is OK (must be at least 700 MiB), moving on..."
+
+echo
+read -p "Press [Enter] key to continue..."
+
+else
+
+	print_build_stage "Host-Memory: $HOST_MEM MiB"
+	print_build_stage "Not enough host memory (less than 1024 MiB, consider upgrading),"
+	print_build_stage "building will use standard XZ options."
+	XZ_OPT="-T0" # alte Standardparameter einsetzen
+
+echo
+read -p "Press [Enter] key to continue..."
+
+fi
+# XZ-TUNING END
+
 if [ -n "${BUILD_ARCH}" ]; then
 	configure_build "${BUILD_ARCH}"
 else
@@ -1760,7 +1800,7 @@
 	buildtoolchain
 	echo "`date -u '+%b %e %T'`: Create toolchain image for ${BUILD_ARCH}" | tee -a $LOGFILE
 	test -d $BASEDIR/cache/toolchains || mkdir -p $BASEDIR/cache/toolchains
-	cd $BASEDIR && XZ_OPT="-T0 -8" tar -Jc --exclude='log/_build.*.log' -f cache/toolchains/$SNAME-$VERSION-toolchain-$TOOLCHAINVER-${BUILD_ARCH}.tar.xz \
+	cd $BASEDIR && $XZ_OPT tar -Jc --exclude='log/_build.*.log' -f cache/toolchains/$SNAME-$VERSION-toolchain-$TOOLCHAINVER-${BUILD_ARCH}.tar.xz \
 		build/${TOOLS_DIR} build/bin/sh log >> $LOGFILE
 	md5sum cache/toolchains/$SNAME-$VERSION-toolchain-$TOOLCHAINVER-${BUILD_ARCH}.tar.xz \
 		> cache/toolchains/$SNAME-$VERSION-toolchain-$TOOLCHAINVER-${BUILD_ARCH}.md5