Bionic (software)

Bionic is an implementation of the standard C library, developed by Google for its Android operating system. It differs from the GNU C Library (glibc) in being designed for devices with less memory and processor power than a typical Linux system. It is a combination of new code and code from FreeBSD, NetBSD, and OpenBSD released under a BSD license, rather than glibc, which uses the GNU Lesser General Public License. This difference was important in the early days of Android, when static linking was common, and is still helpful in introducing Android to software companies used to proprietary operating systems, who can be wary of the LGPL, and unclear about the differences between it and the full GNU General Public License (GPL). Bionic is a C library for use with the Linux kernel, and provides libc, libdl, and libm (libpthread functionality is part of libc, not a separate library as on some other systems). This differs from the BSD C libraries that bionic shares code with, because they require a BSD kernel. The original publicly stated goals for Bionic were the following: BSD-licensed: Google wanted to isolate Android applications from the effect of copyleft licenses to create a proprietary user-space and application ecosystem, but: Android is based on the Linux kernel, which is subject to the copyleft GNU General Public License (GPL) version 2. The most widespread standard C library for the Linux kernel is the GNU C Library (glibc), which is subject to the GNU Lesser General Public License (LGPL), also a copyleft license. In contrast to the GPL, the LGPL explicitly allows for dynamic linking but it does not allow static linking of proprietary software without providing source code or linkable object files. The permissive BSD license is a non-copyleft license that is compatible in both directions. A BSD-licensed glibc substitute could act as an isolation layer between the copyleft core (kernel) and the non-copyleft applications, and was therefore chosen by Google for its Bionic as a glibc substitute.