Forgot to perform 'git add' on most of the files from the previous commit.

src/.config

@@ -2,7 +2,7 @@
 #
 # http://kernel.org
 #
-KERNEL_SOURCE_URL=https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.4.6.tar.xz
+KERNEL_SOURCE_URL=http://kernel.org/pub/linux/kernel/v4.x/linux-4.4.6.tar.xz
 
 # You can find the latest GNU libc source bundles here:
 #
@@ -22,32 +22,32 @@ BUSYBOX_SOURCE_URL=http://busybox.net/downloads/busybox-1.24.2.tar.bz2
 #
 # http://kernel.org/pub/linux/utils/boot/syslinux
 #
-SYSLINUX_SOURCE_URL=https://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-6.03.tar.xz
+SYSLINUX_SOURCE_URL=http://kernel.org/pub/linux/utils/boot/syslinux/syslinux-6.03.tar.xz
 
-###   ###   ###
-###   ###   ###
-###   ###   ###
+###   ###   ###   ###
+###   ###   ###   ###
+###   ###   ###   ###
 
 # Use predefined '.config' file when building the kernel. This overrides the config generation
 # in '02_build_kernel.sh' and the build process uses the config file provided in this parameter.
-# You can comment, leave undefined or use nonexisting file in order to disable the property and
-# rely on automatic config generation. The file location is relative from the source folder.
+# Place the configuration file here: config_predefined/kernel.config
 #
-# KERNEL_CONFIG_FILE=path/to/predefined/kernel.config
+USE_PREDEFINED_KERNEL_CONFIG=false
 
 # Use predefined '.config' file when building BusyBox. This overrides the config generation in
 # '07_build_busybox.sh' and the build process uses the config file provided in this parameter.
-# You can comment, leave undefined or use nonexisting file in order to disable the property and
-# rely on automatic config generation. The file location is relative from the source folder.
+# # Place the configuration file here: config_predefined/busybox.config
 #
-# BUSYBOX_CONFIG_FILE=path/to/predefined/busybox.config
+USE_PREDEFINED_BUSYBOX_CONFIG=false
 
 # Define the overlay type to use. Possible values are 'sparse' and 'folder'. You can use any other
 # value, no value, or comment the property in order to disable it. Put your overlay content in the
 # folder '11_generate_iso' and it will be automatically merged with the root file system on boot.
 # The build process creates either '/minimal.img/rootfs' or '/minimal/rootfs' (read below) and this
-# folder contains all overlay content in it. If the boot media is writeable, then all changes on
-# the root filesystem are automatically persisted.
+# folder contains all overlay content in it. The build process also creates '/minimal.img/work'
+# or '/minimal/work'. This folder is used by the overlay driver to store modifications related
+# to the read only storage. If the overlay media is writeable, then all changes on
+# the root filesystem are automatically persisted and preserved on reboot.
 #
 # sparse - use sparse file 'minimal.img' with hardcoded maximal size of 1MB (see 11_generate_iso.sh).
 #          The generated ISO image is larger because the sparse file is treated as regular file. This
@@ -60,3 +60,8 @@ SYSLINUX_SOURCE_URL=https://www.kernel.org/pub/linux/utils/boot/syslinux/syslinu
 #
 OVERLAY_TYPE=folder
 
+# Use already downloaded source bundles instead of downloading them from internet. This is useful
+# when you have already downloaded the sources and have no internet connection. Or if you want to
+# share your version of "Minimal Linux Live" with predefined sources.
+USE_LOCAL_SOURCE=false
+

src/00_prepare.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-echo "Cleaning up the work area..."
+echo "Cleaning up the work area. This may take a while..."
 rm -rf work
 mkdir work
 

src/01_get_kernel.sh

@@ -1,18 +1,33 @@
 #!/bin/sh
 
+SRC_DIR=$(pwd)
+
 # Grab everything after the '=' character.
 DOWNLOAD_URL=$(grep -i KERNEL_SOURCE_URL .config | cut -f2 -d'=')
 
 # Grab everything after the last '/' character.
 ARCHIVE_FILE=${DOWNLOAD_URL##*/}
 
+# Read the 'USE_LOCAL_SOURCE' property from '.config'
+USE_LOCAL_SOURCE="$(grep -i USE_LOCAL_SOURCE .config | cut -f2 -d'=')"
+
+if [ "$USE_LOCAL_SOURCE" = "true" -a ! -f $SRC_DIR/source/$ARCHIVE_FILE  ] ; then
+  echo "Source bundle $SRC_DIR/source/$ARCHIVE_FILE is missing and will be downloaded."
+  USE_LOCAL_SOURCE="false"
+fi
+
 cd source
 
-# Downloading kernel file.
-# -c option allows the download to resume.
-wget -c $DOWNLOAD_URL
+if [ ! "$USE_LOCAL_SOURCE" = "true" ] ; then
+  # Downloading kernel source bundle file. The '-c' option allows the download to resume.
+  echo "Downloading kernel source bundle from '$DOWNLOAD_URL'."
+  wget -c $DOWNLOAD_URL
+else
+  echo "Using local kernel source bundle $SRC_DIR/source/$ARCHIVE_FILE"
+fi
 
 # Delete folder with previously extracted kernel.
+echo "Removing kernel work area..."
 rm -rf ../work/kernel
 mkdir ../work/kernel
 

src/02_build_kernel.sh

@@ -8,16 +8,24 @@ cd work/kernel
 cd $(ls -d *)
 
 # Cleans up the kernel sources, including configuration files.
+echo "Preparing kernel work area..."
 make mrproper
 
-# Read the 'KERNEL_CONFIG_FILE' property from '.config'
-KERNEL_CONFIG_FILE="$SRC_DIR/$(grep -i KERNEL_CONFIG_FILE $SRC_DIR/.config | cut -f2 -d'=')"
+# Read the 'USE_PREDEFINED_KERNEL_CONFIG' property from '.config'
+USE_PREDEFINED_KERNEL_CONFIG="$(grep -i USE_PREDEFINED_KERNEL_CONFIG $SRC_DIR/.config | cut -f2 -d'=')"
 
-if [ -f $KERNEL_CONFIG_FILE ] ; then
+if [ "$USE_PREDEFINED_KERNEL_CONFIG" = "true" -a ! -f $SRC_DIR/config_predefined/kernel.config ] ; then
+  echo "Config file $SRC_DIR/config_predefined/kernel.config does not exist."
+  USE_PREDEFINED_KERNEL_CONFIG="false"
+fi
+
+if [ "$USE_PREDEFINED_KERNEL_CONFIG" = "true" ] ; then
   # Use predefined configuration file for the kernel.
-  cp $KERNEL_CONFIG_FILE .config
+  echo "Using config file $SRC_DIR/config_predefined/kernel.config"  
+  cp -f $SRC_DIR/config_predefined/kernel.config .config
 else
   # Create default configuration file for the kernel.
+  echo "Generating default kernel configuration..."
   make defconfig
 
   # Changes the name of the system to 'minimal'.
@@ -30,10 +38,12 @@ fi
 # Compile the kernel with optimization for 'parallel jobs' = 'number of processors'.
 # Good explanation of the different kernels:
 # http://unix.stackexchange.com/questions/5518/what-is-the-difference-between-the-following-kernel-makefile-terms-vmlinux-vmlinux
+echo "Building kernel..."
 make bzImage -j $(grep ^processor /proc/cpuinfo | wc -l)
 
 # Install kernel headers in './usr' (this is not '/usr') which are used later
 # when we build and configure the GNU C library (glibc).
+echo "Generating kernel headers..."
 make headers_install
 
 cd ../../..

src/03_get_glibc.sh

@@ -1,18 +1,33 @@
 #!/bin/sh
 
+SRC_DIR=$(pwd)
+
 # Grab everything after the '=' character.
 DOWNLOAD_URL=$(grep -i GLIBC_SOURCE_URL .config | cut -f2 -d'=')
 
 # Grab everything after the last '/' character.
 ARCHIVE_FILE=${DOWNLOAD_URL##*/}
 
+# Read the 'USE_LOCAL_SOURCE' property from '.config'
+USE_LOCAL_SOURCE="$(grep -i USE_LOCAL_SOURCE .config | cut -f2 -d'=')"
+
+if [ "$USE_LOCAL_SOURCE" = "true" -a ! -f $SRC_DIR/source/$ARCHIVE_FILE  ] ; then
+  echo "Source bundle $SRC_DIR/source/$ARCHIVE_FILE is missing and will be downloaded."
+  USE_LOCAL_SOURCE="false"
+fi
+
 cd source
 
-# Downloading glibc file.
-# -c option allows the download to resume.
-wget -c $DOWNLOAD_URL
+if [ ! "$USE_LOCAL_SOURCE" = "true" ] ; then
+  # Downloading glibc source bundle file. The '-c' option allows the download to resume.
+  echo "Downloading glibc source bundle from '$DOWNLOAD_URL'."
+  wget -c $DOWNLOAD_URL
+else
+  echo "Using local glibc source bundle $SRC_DIR/source/$ARCHIVE_FILE"
+fi
 
 # Delete folder with previously extracted glibc.
+echo "Removing glibc work area..."
 rm -rf ../work/glibc
 mkdir ../work/glibc
 

src/04_build_glibc.sh

@@ -12,10 +12,12 @@ cd work/glibc
 cd $(ls -d *)
 
 # Prepare working area, e.g. 'work/glibc/glibc-2.23/glibc_objects'.
+echo "Preparing glibc object area..."
 rm -rf ./glibc_objects
 mkdir glibc_objects
 
-# Prepare installation area, e.g. 'work/glibc/glibc-2.23/glibc_installed'.
+# Prepare install area, e.g. 'work/glibc/glibc-2.23/glibc_installed'.
+echo "Preparing glibc install area..."
 rm -rf ./glibc_installed
 mkdir glibc_installed
 cd glibc_installed
@@ -27,12 +29,15 @@ cd ../glibc_objects
 # glibc is configured to use the root folder (--prefix=) and as result all libraries
 # will be installed in '/lib'. Kernel headers are taken from our already prepared
 # kernel header area (see 02_build_kernel.sh). Packages 'gd' and 'selinux' are disabled.
+echo "Configuring glibc..."
 ../configure --prefix= --with-headers=$WORK_KERNEL_DIR/usr/include --without-gd --without-selinux --disable-werror
 
 # Compile glibc with optimization for "parallel jobs" = "number of processors".
+echo "Building glibc..."
 make -j $(grep ^processor /proc/cpuinfo | wc -l)
 
 # Install glibc in the installation area, e.g. 'work/glibc/glibc-2.23/glibc_installed'.
+echo "Installing glibc..."
 make install DESTDIR=$GLIBC_INSTALLED -j $(grep ^processor /proc/cpuinfo | wc -l)
 
 cd ../../..

src/05_prepare_glibc.sh

@@ -25,14 +25,14 @@ cd glibc_installed
 # |  |
 # |  +--asm-generic (kernel)
 # |  |
-# |  +--asm-generic (kernel)
-# |  |
 # |  +--linux (kernel)
 # |  |
 # |  +--mtd (kernel)
 # |
 # +--lib (glibc)
 
+echo "Preparing glibc..."
+
 mkdir -p usr
 cd usr
 

src/06_get_busybox.sh

@@ -1,18 +1,33 @@
 #!/bin/sh
 
+SRC_DIR=$(pwd)
+
 # Grab everything after the '=' character.
 DOWNLOAD_URL=$(grep -i BUSYBOX_SOURCE_URL .config | cut -f2 -d'=')
 
 # Grab everything after the last '/' character.
 ARCHIVE_FILE=${DOWNLOAD_URL##*/}
 
+# Read the 'USE_LOCAL_SOURCE' property from '.config'
+USE_LOCAL_SOURCE="$(grep -i USE_LOCAL_SOURCE .config | cut -f2 -d'=')"
+
+if [ "$USE_LOCAL_SOURCE" = "true" -a ! -f $SRC_DIR/source/$ARCHIVE_FILE  ] ; then
+  echo "Source bundle $SRC_DIR/source/$ARCHIVE_FILE is missing and will be downloaded."
+  USE_LOCAL_SOURCE="false"
+fi
+
 cd source
 
-# Downloading busybox source.
-# -c option allows the download to resume.
-wget -c $DOWNLOAD_URL
+if [ ! "$USE_LOCAL_SOURCE" = "true" ] ; then
+  # Downloading BusyBox source bundle file. The '-c' option allows the download to resume.
+  echo "Downloading BusyBox source bundle from '$DOWNLOAD_URL'."
+  wget -c $DOWNLOAD_URL
+else
+  echo "Using local BusyBox source bundle $SRC_DIR/source/$ARCHIVE_FILE"
+fi
 
 # Delete folder with previously extracted busybox.
+echo "Removing BusyBox work area..."
 rm -rf ../work/busybox
 mkdir ../work/busybox
 

src/07_build_busybox.sh

@@ -15,16 +15,24 @@ cd work/busybox
 cd $(ls -d *)
 
 # Remove previously generated artifacts.
+echo "Preparing BusyBox work area..."
 make distclean
 
-# Read the 'BUSYBOX_CONFIG_FILE' property from '.config'
-BUSYBOX_CONFIG_FILE="$SRC_DIR/$(grep -iBUSYBOX_CONFIG_FILE $SRC_DIR/.config | cut -f2 -d'=')"
+# Read the 'USE_PREDEFINED_BUSYBOX_CONFIG' property from '.config'
+USE_PREDEFINED_BUSYBOX_CONFIG="$(grep -i USE_PREDEFINED_BUSYBOX_CONFIG $SRC_DIR/.config | cut -f2 -d'=')"
 
-if [ -f $BUSYBOX_CONFIG_FILE ] ; then
+if [ "$USE_PREDEFINED_BUSYBOX_CONFIG" = "true" -a ! -f $SRC_DIR/config_predefined/busybox.config ] ; then
+  echo "Config file $SRC_DIR/config_predefined/busybox.config does not exist."
+  USE_PREDEFINED_BUSYBOX_CONFIG="false"
+fi
+
+if [ "$USE_PREDEFINED_BUSYBOX_CONFIG" = "true" ] ; then
   # Use predefined configuration file for Busybox.
-  cp $BUSYBOX_CONFIG_FILE .config
+  echo "Using config file $SRC_DIR/config_predefined/busybox.config"  
+  cp -f $SRC_DIR/config_predefined/busybox.config .config
 else
   # Create default configuration file.
+  echo "Generating default BusyBox configuration..."  
   make defconfig
   
   # The 'inetd' applet fails to compile because we use the glibc installation area as
@@ -41,9 +49,11 @@ GLIBC_INSTALLED_ESCAPED=$(echo \"$GLIBC_INSTALLED\" | sed 's/\//\\\//g')
 sed -i "s/.*CONFIG_SYSROOT.*/CONFIG_SYSROOT=$GLIBC_INSTALLED_ESCAPED/" .config
 
 # Compile busybox with optimization for "parallel jobs" = "number of processors".
+echo "Building BusyBox..."
 make busybox -j $(grep ^processor /proc/cpuinfo | wc -l)
 
 # Create the symlinks for busybox. The file 'busybox.links' is used for this.
+echo "Generating BusyBox based initramfs area..."
 make install
 
 cd ../../..

src/08_generate_rootfs.sh

@@ -10,6 +10,7 @@ cd ../../../..
 
 cd work
 
+echo "Preparing initramfs work area..."
 rm -rf rootfs
 
 cd busybox

src/08_generate_rootfs/etc/inittab

@@ -1,8 +1,8 @@
 ::sysinit:/etc/bootscript.sh
 ::restart:/sbin/init
-::shutdown:echo "Syncing file buffers..."
-::shutdown:/bin/sync
-::shutdown:echo "Unmounting all filesystems..."
+::shutdown:echo "Sync file buffers..."
+::shutdown:sync
+::shutdown:echo "Unmount all filesystems..."
 ::shutdown:umount -a -r
 ::ctrlaltdel:/sbin/reboot
 ::once:cat /etc/welcome.txt

src/08_generate_rootfs/init

@@ -3,8 +3,14 @@
 echo "Welcome to \"Minimal Linux Live\" (/init)"
 
 # Let's mount all core file systems.
-/etc/prepare.sh
+/etc/01_prepare.sh
 
-# Now let's create new mountpoint in RAM and make it our new root location.
-exec /etc/switch.sh
+# Create new mountpoint in RAM, make it our new root location and overlay it
+# with our storage area (if overlay area exists at all). This operation invokes
+# the script '/etc/03_switch.sh' as the new init process.
+exec /etc/02_overlay.sh
 
+echo "(/init) - you can never see this unless there is a serious bug..."
+
+# Wait until any key has been pressed.
+read -n1 -s

src/09_pack_rootfs.sh

@@ -8,6 +8,7 @@ rm -f rootfs.cpio.gz
 cd rootfs
 
 # Packs the current 'initramfs' folder structure in 'cpio.gz' archive.
+echo "Packing initramfs..."
 find . | cpio -R root:root -H newc -o | gzip > ../rootfs.cpio.gz
 
 cd ../..

src/10_get_syslinux.sh

@@ -1,18 +1,33 @@
 #!/bin/sh
 
+SRC_DIR=$(pwd)
+
 # Grab everything after the '=' character.
 DOWNLOAD_URL=$(grep -i SYSLINUX_SOURCE_URL .config | cut -f2 -d'=')
 
 # Grab everything after the last '/' character.
 ARCHIVE_FILE=${DOWNLOAD_URL##*/}
 
+# Read the 'USE_LOCAL_SOURCE' property from '.config'
+USE_LOCAL_SOURCE="$(grep -i USE_LOCAL_SOURCE .config | cut -f2 -d'=')"
+
+if [ "$USE_LOCAL_SOURCE" = "true" -a ! -f $SRC_DIR/source/$ARCHIVE_FILE  ] ; then
+  echo "Source bundle $SRC_DIR/source/$ARCHIVE_FILE is missing and will be downloaded."
+  USE_LOCAL_SOURCE="false"
+fi
+
 cd source
 
-# Downloading Syslinux file.
-# -c option allows the download to resume.
-wget -c $DOWNLOAD_URL
+if [ ! "$USE_LOCAL_SOURCE" = "true" ] ; then
+  # Downloading SYSLINUX source bundle file. The '-c' option allows the download to resume.
+  echo "Downloading SYSLINUX source bundle from '$DOWNLOAD_URL'."
+  wget -c $DOWNLOAD_URL
+else
+  echo "Using local SYSLINUX source bundle $SRC_DIR/source/$ARCHIVE_FILE"
+fi
 
 # Delete folder with previously extracted Syslinux.
+echo "Removing SYSLINUX work area..."
 rm -rf ../work/syslinux
 mkdir ../work/syslinux
 

src/11_generate_iso.sh

@@ -15,12 +15,15 @@ WORK_SYSLINUX_DIR=$(pwd)
 cd ../../..
 
 # Remove the old ISO file if it exists.
+echo "Removing old ISO image..."
 rm -f minimal_linux_live.iso
 
 # Remove the old ISO generation area if it exists.
+echo "Removing old ISO image work area..."
 rm -rf work/isoimage
 
 # This is the root folder of the ISO image.
+echo "Preparing ISO image work area..."
 mkdir work/isoimage
 cd work/isoimage
 
@@ -80,7 +83,7 @@ if [ "$OVERLAY_TYPE" = "sparse" -a "$(id -u)" = "0" ] ; then
   # Copy the overlay content.
   cp -r $SRC_DIR/11_generate_iso/* sparse/rootfs/
   
-  # Unmount the sparse file and thelete the temporary folder.
+  # Unmount the sparse file and delete the temporary folder.
   $BUSYBOX umount sparse
   rm -rf sparse
   
@@ -95,7 +98,9 @@ elif [ "$OVERLAY_TYPE" = "folder" ] ; then
   mkdir -p minimal/rootfs
   mkdir -p minimal/work  
   
-  cp -r $SRC_DIR/11_generate_iso/* minimal/rootfs/
+  cp -rf $SRC_DIR/11_generate_iso/* minimal/rootfs/
+else
+  echo "Generated ISO image will have no overlay structure."
 fi
 
 # Create ISOLINUX configuration file.

src/Makefile

@@ -17,6 +17,8 @@ clean:
 	@rm -rf work
 	@echo "Removing generated ISO image..."
 	@rm -f minimal_linux_live.iso
+	@echo "Removing predefined configuration files..."
+	@rm -f config_predefined/*.config
 	@echo "Removing build log file..."
 	@rm -f minimal_linux_live.log
 

src/generate_hdd.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+# Create sparse file of 20MB which can be used by QEMU.
+
+rm -f hdd.img
+truncate -s 20M hdd.img
+

src/qemu32.sh

@@ -1,9 +1,17 @@
 #!/bin/sh
 
-qemu-system-i386 -m 64M -cdrom minimal_linux_live.iso -boot d
+# Use this script without arguments to run the generated ISO image with QEMU.
+# If you pass '-hdd' or '-h' the virtual hard disk 'hdd.img' will be attached.
+# Note that this virtual hard disk has to be created in advance. You can use
+# the script 'generate_hdd.sh' to generate the hard disk image file. Once you
+# have hard disk image, you can use it as overlay device and persist all your
+# changes. See the '.config' file for more information on the overlay support.
 
-# Use this when you want to play with hard disk content. You can manually create
-# sparse file (/minimal.img) and put overlay content (/minimal.img/rootfs) in it.
-#
-# qemu-system-i386 -m 64M -hda hdd.img -cdrom minimal_linux_live.iso -boot d
+if [ "$1" = "-hdd" -o "$1" = "-h" ] ; then
+  echo "Starting QEMU with attached ISO image and hard disk."
+  qemu-system-i386 -m 64M -hda hdd.img -cdrom minimal_linux_live.iso -boot d
+else
+  echo "Starting QEMU with attached ISO image."
+  qemu-system-i386 -m 64M -cdrom minimal_linux_live.iso -boot d
+fi
 

src/qemu64.sh

@@ -1,8 +1,17 @@
 #!/bin/sh
 
-qemu-system-x86_64 -m 64M -cdrom minimal_linux_live.iso -boot d
+# Use this script without arguments to run the generated ISO image with QEMU.
+# If you pass '-hdd' or '-h' the virtual hard disk 'hdd.img' will be attached.
+# Note that this virtual hard disk has to be created in advance. You can use
+# the script 'generate_hdd.sh' to generate the hard disk image file. Once you
+# have hard disk image, you can use it as overlay device and persist all your
+# changes. See the '.config' file for more information on the overlay support.
+
+if [ "$1" = "-hdd" -o "$1" = "-h" ] ; then
+  echo "Starting QEMU with attached ISO image and hard disk."
+  qemu-system-x86_64 -m 64M -hda hdd.img -cdrom minimal_linux_live.iso -boot d
+else
+  echo "Starting QEMU with attached ISO image."
+  qemu-system-x86_64 -m 64M -cdrom minimal_linux_live.iso -boot d
+fi
 
-# Use this when you want to play with hard disk content. You can manually create
-# sparse file (/minimal.img) and put overlay content (/minimal.img/rootfs) in it.
-#
-# qemu-system-x86_64 -m 64M -hda hdd.img -cdrom minimal_linux_live.iso -boot d