1.1.1 The Red Layer
The red layer from figure 1 represents the services offered by the Linux kernel and associated GNU utility packages ported to the ARM architecture. These components are licensed under the GNU General Public License, the GPL, or the GNU Lesser General Public License, the LGPL. Being subject to the GNU GPL and LGPL licenses, these components are licensed with all source code included. Furthermore, due to the viral nature of the GPL license, any modification to this layer or derived work must be distributed as source to any 3rd parties using the same licensing terms. The GNU/Linux ARM port is mature, stable, and used in many embedded projects both in and outside of Google.
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1.1.2 The Green Layer
The green layer consists entirely of open source libraries available under various licenses. Some of the libraries come from the GNU project itself. The licenses here vary from the LGPL, BSD, MIT and are completely in the public domain in the case of the SQLite database. However, even if the licenses of some of the components found in this layer are more permissive and could allow a hardware vendor for customizations not found in other Android handsets, Google has created the Open Handset Alliance that owns the Android trademark. As part of this effort, any phone that wishes to be branded as an Android handset must meet the non-fragmentation rule. As such, any phone that would customize the libraries found in this layer, add libraries or remove them altogether would no longer be able to brand itself as an Android phone. Furthermore, under this same pledge, its license to the proprietary Dalvik virtual machine found at the core of the Android platform would be considered null and void.