mkrootfs

mkrootfs.sh is a bash script for compile and create a rootfs for embedded systems.

This is a project for the RTOS course (look at the end of this readme for the original assignment).

Usage

Run the script with '--help' option for more details about options and usage; an equivalent manpage should be provided (mkrootfs.1).

The Makefile contains some usefull commands or shortcuts, run 'make help' for more details; for example 'make download' is a simple way for downloading some tools like Busybox.

The etc.tar.xz archive contains a minimal configuration for a rootfs; between test programs, there's an etc directory for experiments and customizations.

Some C/C++ programs are provided for testing in 'test_programs/'.

An auxiliary script ldd.sh is attached, required for the "libraries filter" option -l; it uses additional tools like readlink and readelf (that should be provided by binutils)

Requirements

• Shell bash 4.3.30 or greater
• Some standard/classic Linux utilities: cp, rm, ln, mkdir, chmod, dirname, basename
• Other tools: tar, find, cpio, gzip
• If you want to compile something, typically you need make
• For ldd.sh: find, readlink, basename
• Some space on your disk (it depends on what you want install)
• All the dependencies of what you want compile/install (typically a compiler or a complete GNU toolchain)

TODO

• deallocate variables
• default etc/
  • some init script require some busybox component (eg mdev) that can be not included
• do not re-compile or build what you have already built successfully before
  • this might be more difficult than expected
• some other interesting utilities? dropbear ssh? lua interpreter? ....

Assignment

• no external dependencies
• support cross-compilation
  • build cross-compiler (optional)
• support inclusion of custom:
  • programs
  • kernel modules
  • boot script
• non-interactive, support command-line
• size reduced to the minimum
• able to run in Qemu
  • arm + linux + uclibc-ng
  • arm + linux + libc
  • x86_64 + linux + libc
  • mips + linux + uclibc-ng

Original assignment:

Write a set of shell scripts allowing to create a ramfs or initrd for embedded systems. The scripts must not have external dependencies and must support cross-compilation (optional: allow to build the cross-compiler). The inclusion of custom programs, kernel modules, or boot scripts in the image must be supported. The shell script must be non-interactive (controlled through command-line parameters. Use "getopt" to parse them). The size of the initramfs must be reduced to the minimum. The resulting image must be able to run in Qemu.