Scratchbox 2
Scratchbox 2 (often abbreviated to "sb2" or "sbox2") is a cross-compilation toolkit designed to make embedded Linux application development easier.  It also provides a full set of tools to integrate and cross-compile an entire Linux distribution.

Functional description
In the Linux world, when building software, many parameters are auto-detected on the host system (like installed libraries and system configuration), for example through Autotools' ./configure scripts.  When one wants to build software for an embedded target by cross-compilation, most auto-detected parameters are incorrect: I.e. host configuration is not the same as the embedded target's configuration, hence the name cross-compilation.

Without Scratchbox 2, one has to manually set many parameters and "hack" the "configure process" to generate working executable code for the embedded target.

Scratchbox 2 allows one to set up a "virtual" environment that will trick Autotools and other executables into thinking that they are directly running on the embedded target with its configuration.

Moreover, Scratchbox 2 provides a technology called CPU-transparency that goes further: With CPU-transparency, executables built for the host CPU or for the target CPU could be executed directly on the host with sb2 handling the task to emulate a different CPU-architecture if necessary to run software components compiled for the target CPU.  Hence a build process can mix using programs built for different CPU-architectures.  That is especially useful when a build process requires to build a software component first as a build dependency for building another software component: For example, a "Lexer" must be built first in order to generate code for / of another software component with it.

Projects using Scratchbox 2
 Tizen
 Maemo
 MeeGo / Mer
 Sailfish OS
 WIDK − WebOS Internals Development Kit
 Raspberry Pi (used to build binaries for the Raspberry Pi alpha board)

Historic Git repositories of Scratchbox 2
 BinChengfei/scratchbox2 at GitHub provides an unaltered mirror of the former Scratchbox 2 Git repository at Gitorious with its latest Git tag being 2.3.90 on 2012-09-05.
 lbt/scratchbox2 (up to tag pkg-mer-2.3.90-4 on 2013-04-25) and mer-packages/scratchbox2 (up to tag 2.3.90-git2 on 2014-03-05), both at GitHub, show intermediate states before the Nemo / Mer merger, when Scratchbox 2's active source tree was moved to the now dissolved git.merproject.org.
 The continuation of the former source code repository git.merproject.org/mer-core/scratchbox2 is sailfishos/scratchbox2 at GitHub, which contains all commit history and Git tags of all aforementioned Git repositories.

References

External links
 Scratchbox 2 documentation
 Archive of the original Scratchbox 2 website

Embedded Linux
Build automation