Now that all the information relating to the root filesystem has been presented to you, it would be good exercise to describe the must-have components of the minimal root filesystem. This would not only help you to understand the rootfs structure and its dependencies better, but also help with requirements needed for boot time and the size optimization of the root filesystem.

The starting point to describe the components is /sbin/init; here, by using the ldd command, the runtime dependencies can be found. For the Yocto Project, the ldd /sbin/init command returns:

linux-gate.so.1 (0xb7785000)
libc.so.6 => /lib/libc.so.6 (0x4273b000)
/lib/ld-linux.so.2 (0x42716000)

From this information, the /lib directory structure is defined. Its minimal form is:

lib
|-- ld-2.3.2.so
|-- ld-linux.so.2 -> ld-2.3.2.so
|-- libc-2.3.2.so
'-- libc.so.6 -> libc-2.3.2.so

The following symbolic links to ensure backward compatibility and version immunity for the libraries. The linux...