Linux on Mobile Devices

Although Android is based on the Linux kernel, it is the GNU userland that really makes up "GNU/Linux", the operating system that we know and love; and in Android, it has been completely supplanted by their own, Apache-based userland, "Android/Linux".

As a result, Android is binary-compatible with Linux programs, but cannot run anything graphical without large additions.

There are ways to add Linux compatibility

Linux Chroot (All Devices)

Because Android uses the Linux kernel, all we need to do to install GNU/Linux is to change the apparent root directory. This is called a chroot.

This method works on every device, and is ideal for command-line applications.

However, since Android is still in control of the display drivers, X Windows applications must use a VNC Remote Desktop. This can add significant overhead on top of the existing Android system, so only newer smartphones can run graphical apps efficiently.

Native GNU/Linux Ports

Full blown GNU/Linux, with full compatibility for any ARM-compiled "Linux" app.

Ubuntu Desktop (Nexus 7)
KDE Plasma Active + Mer (Nexus 7)
UbnHD2 (HTC HD2)
(HTC Desire HD)
(HP Touchpad)

Linux Kernel Based

Ports of mobile operating systems that use the Linux kernel, but are not "GNU/Linux" and have their own applications.

Ubuntu Phone (Nexus 4, Galaxy Nexus)
Open WebOS (Galaxy Nexus)
Firefox OS (Galaxy Nexus)

Linux on Mobile Devices - bibanon/android-development-codex GitHub Wiki