Externalized the additional CFLAGS. Removed the isohybrid functionality. These changes haven't been tested yet.

src/.config

@@ -45,7 +45,7 @@ SYSLINUX_SOURCE_URL=http://kernel.org/pub/linux/utils/boot/syslinux/syslinux-6.0
 #
 #   http://links.twibright.com
 #
-LINKS_SOURCE_URL=http://links.twibright.com/download/links-2.13.tar.bz2
+LINKS_SOURCE_URL=http://links.twibright.com/download/links-2.14.tar.bz2
 
 # You can find the latest Dropbear source bundles here:
 #
@@ -166,3 +166,7 @@ USE_BOOT_LOGO=true
 # value '2' and if your CPU has 4 cores, then the number of 'make' jobs will be
 # 4 * 2 = 8. Don't change this property unless you know what 'make' jobs are!
 JOB_FACTOR=1
+
+# This property defines the default GCC flags to be used during the compilation
+# process. You can use your own flags here or even completely remove the flags.
+CFLAGS=-Os -s -fno-stack-protector -fomit-frame-pointer -U_FORTIFY_SOURCE

src/02_build_kernel.sh

@@ -7,6 +7,9 @@ SRC_DIR=$(pwd)
 # Read the 'JOB_FACTOR' property from '.config'
 JOB_FACTOR="$(grep -i ^JOB_FACTOR .config | cut -f2 -d'=')"
 
+# Read the 'CFLAGS' property from '.config'
+CFLAGS="$(grep -i ^CFLAGS .config | cut -f2 -d'=')"
+
 # Find the number of available CPU cores.
 NUM_CORES=$(grep ^processor /proc/cpuinfo | wc -l)
 
@@ -91,7 +94,7 @@ fi
 # http://unix.stackexchange.com/questions/5518/what-is-the-difference-between-the-following-kernel-makefile-terms-vmlinux-vmlinux
 echo "Building kernel..."
 make \
-  CFLAGS="-Os -s -fno-stack-protector -U_FORTIFY_SOURCE" \
+  CFLAGS="$CFLAGS" \
   bzImage -j $NUM_JOBS
 
 # Install the kernel file.

src/04_build_glibc.sh

@@ -7,6 +7,9 @@ SRC_DIR=$(pwd)
 # Read the 'JOB_FACTOR' property from '.config'
 JOB_FACTOR="$(grep -i ^JOB_FACTOR .config | cut -f2 -d'=')"
 
+# Read the 'CFLAGS' property from '.config'
+CFLAGS="$(grep -i ^CFLAGS .config | cut -f2 -d'=')"
+
 # Find the number of available CPU cores.
 NUM_CORES=$(grep ^processor /proc/cpuinfo | wc -l)
 
@@ -50,7 +53,7 @@ $GLIBC_SRC/configure \
   --without-gd \
   --without-selinux \
   --disable-werror \
-  CFLAGS="-Os -s -fno-stack-protector -U_FORTIFY_SOURCE -fomit-frame-pointer"
+  CFLAGS="$CFLAGS"
 
 # Compile glibc with optimization for "parallel jobs" = "number of processors".
 echo "Building glibc..."

src/07_build_busybox.sh

@@ -58,10 +58,13 @@ GLIBC_PREPARED_ESCAPED=$(echo \"$GLIBC_PREPARED\" | sed 's/\//\\\//g')
 # Now we tell BusyBox to use the glibc prepared area.
 sed -i "s/.*CONFIG_SYSROOT.*/CONFIG_SYSROOT=$GLIBC_PREPARED_ESCAPED/" .config
 
+# Read the 'CFLAGS' property from '.config'
+CFLAGS="$(grep -i ^CFLAGS .config | cut -f2 -d'=')"
+
 # Compile busybox with optimization for "parallel jobs" = "number of processors".
 echo "Building BusyBox..."
 make \
-  EXTRA_CFLAGS="-Os -s -fno-stack-protector -U_FORTIFY_SOURCE" \
+  EXTRA_CFLAGS="$CFLAGS" \
   busybox -j $NUM_JOBS
 
 # Create the symlinks for busybox. The file 'busybox.links' is used for this.

src/12_generate_iso.sh

@@ -153,10 +153,6 @@ genisoimage \
   -boot-info-table \
   ./
 
-# This allows the ISO image to be bootable if it is burned on USB flash drive.
-# The -u option is used in EFI boot mode and it reduces the ISO image size.
-isohybrid -u ../minimal_linux_live.iso 2>/dev/null || true
-
 # Copy the ISO image to the root project folder.
 cp ../minimal_linux_live.iso ../../
 

src/overlay_00_clean.sh

@@ -6,15 +6,14 @@ echo "Cleaning up the overlay work area. This may take a while..."
 rm -rf work/overlay
 mkdir -p work/overlay
 
-# Just in case we execute the overlay software generation script before we
-# execute the main build script.
 mkdir -p work/src/minimal_overlay
 
-# -p stops errors if the directory already exists
+# -p stops errors if the directory already exists.
 mkdir -p source/overlay
 
-cd minimal_overlay
+cd work/src/minimal_overlay
 
+# Remove all previously prepared overlay artifacts.
 for dir in $(ls -d */ 2>/dev/null) ; do
   rm -rf $dir
   echo "Overlay folder '$dir' has been removed."

src/overlay_dropbear_02_build.sh

@@ -5,6 +5,9 @@ SRC_DIR=$(pwd)
 # Read the 'JOB_FACTOR' property from '.config'
 JOB_FACTOR="$(grep -i ^JOB_FACTOR .config | cut -f2 -d'=')"
 
+# Read the 'CFLAGS' property from '.config'
+CFLAGS="$(grep -i ^CFLAGS .config | cut -f2 -d'=')"
+
 # Find the number of available CPU cores.
 NUM_CORES=$(grep ^processor /proc/cpuinfo | wc -l)
 
@@ -31,7 +34,7 @@ echo "Configuring Dropbear..."
   --prefix=$SRC_DIR/work/overlay/dropbear/dropbear_installed \
   --disable-zlib \
   --disable-loginfunc \
-  CFLAGS="-Os -s -fno-stack-protector -U_FORTIFY_SOURCE"
+  CFLAGS="$CFLAGS"
 
 echo "Building Dropbear..."
 make -j $NUM_JOBS

src/overlay_links_02_build.sh

@@ -5,6 +5,9 @@ SRC_DIR=$(pwd)
 # Read the 'JOB_FACTOR' property from '.config'
 JOB_FACTOR="$(grep -i ^JOB_FACTOR .config | cut -f2 -d'=')"
 
+# Read the 'CFLAGS' property from '.config'
+CFLAGS="$(grep -i ^CFLAGS .config | cut -f2 -d'=')"
+
 # Find the number of available CPU cores.
 NUM_CORES=$(grep ^processor /proc/cpuinfo | wc -l)
 
@@ -32,7 +35,7 @@ echo "Configuring Links..."
   --without-x
 
 # Set CFLAGS directly in Makefile.
-sed -i "s/^CFLAGS = .*/CFLAGS = \\-Os \\-s \\-fno\\-stack\\-protector \\-U_FORTIFY_SOURCE/" Makefile
+sed -i "s/^CFLAGS = .*/CFLAGS = $CFLAGS/" Makefile
 
 echo "Building Links..."
 make -j $NUM_JOBS