Common Properties And Functions

The shell script file common.sh is sourced in all MLL scripts. It provides common properties and functions.

Properties

SRC_DIR

SRC_DIR=src/

This is the main source directory, i.e. the property references the main project directory src/.

CONFIG

CONFIG=src/.config

This is the main configuration file. The configuration properties are described here.

SOURCE_DIR

SOURCE_DIR=src/source/

This is the directory where all source archives are downloaded.

WORK_DIR

WORK_DIR=src/work/

This is the directory where all MLL artifacts are processed. All build actions happen in this directory.

KERNEL_INSTALLED

KERNEL_INSTALLED=src/work/kernel/kernel_installed/

This is the directory where the kernel and its corresponding header files are placed after the kernel build phase has been completed.

GLIBC_OBJECTS

GLIBC_OBJECTS=src/work/glibc/glibc_objects/

This is the directory where the GNU C Library is going to be built.

GLIBC_INSTALLED

GLIBC_INSTALLED=src/work/glibc/glibc_installed/

This is the directory where the GNU C Library shared objects (.so files) are placed after the build phase has been completed.

BUSYBOX_INSTALLED

BUSYBOX_INSTALLED=src/work/busybox/busybox_installed/

This is the directory where Busybox is placed after the build phase has been completed.

SYSROOT

SYSROOT=src/work/sysroot/

The system root folder for MLL. This folder contains GLIBC, and kernel header files. MLL uses the sysroot folder in order to properly link Busybox with the custom built kernel and GLIBC.

ROOTFS

ROOTFS=src/work/rootfs/

This folder contains the rootfs/initramfs structure which is generated by the core MLL build process.

OVERLAY_ROOTFS

OVERLAY_ROOTFS=src/work/overlay_rootfs/

This folder contains the rootfs/initramfs structure which is generated by the overlay subsystem build process.

ISOIMAGE

OVERLAY_ROOTFS=src/work/isoimage/

This folder contains the final ISO image structure.

ISOIMAGE_OVERLAY

OVERLAY_ROOTFS=src/work/isoimage_overlay/

This folder contains the final overlay subsystem ISO structure.

Functions

read_property(prop_name)

This function reads properties from the main .config file.

# Example

JOB_FACTOR=`read_property JOB_FACTOR`

download_source(url, file_to_save)

This function downloads the url resource and saves it as $file_to_save.

# Example
#
# This is the filesystem structure before the execution
# of the function.
#
# src/
# └── source/
#     └── (no files/folders)

download_source \
  'https://busybox.net/downloads/busybox-1.32.0.tar.bz2' \
  $SOURCE_DIR/busybox-1.32.0.tar.bz2
  
# This is the filesystem structure after the execution
# of the function.
#
# src/
# └── source/
#     └── busybox-1.32.0.tar.bz2

extract_source(archive_file, dest_dir)

This function extracts the archive archive_file in the directory src/work/$dest_dir/.

# Example
#
# This is the filesystem structure before the execution
# of the function.
#
# src/
# ├── source/
# │   └── busybox-1.32.0.tar.bz2
# └── work/
#     └── (no files/folders)

extract_source \
  $SOURCE_DIR/busybox-1.32.0.tar.bz2 \
  busybox
  
# This is the filesystem structure after the execution
# of the function.
#
# src/
# ├── source/
# │   └── busybox-1.32.0.tar.bz2
# └── work/
#     └── busybox
#         └── busybox-1.32.0/