science

Scratchbox 2

Scratchbox 2 is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Scratchbox 2 rather than just read about it. In short: 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.

Key takeaways

Scratchbox 2 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Scratchbox 2 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Scratchbox 2 from memory before moving on to harder problems.

Reference excerpt

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.

Predecessor Scratchbox was a Linux embedded application development toolkit which also provided cross-compilation support for Linux distributions. The project was initially developed by Movial and was sponsored by Nokia. It was licensed under the GNU General Public License (GPL). Scratchbox was designed for the Maemo development platform (Nokia 770, N800, N810 Internet Tablets and Nokia N900 and N9 phones) and supported ARM architecture and x86. Targets like PowerPC and MIPS architecture worked at experimental level.

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 technique 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.

Historic Git repositories of Scratchbox 2 BinChengfei/scratchbox2 at GitHub provided 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 An archived version of the original Scratchbox 2 website at the Wayback Machine (archived 2013-06-02)

Worked examples

Example 1 — a first encounter with Scratchbox 2

Start with the simplest possible case. Write down what Scratchbox 2 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Scratchbox 2 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Scratchbox 2 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Scratchbox 2

In research: Scratchbox 2 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Scratchbox 2 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Scratchbox 2 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Build automation, Embedded Linux, so understanding it makes those chapters shorter.
In everyday life: Look for Scratchbox 2 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Scratchbox 2 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Scratchbox 2 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Scratchbox 2 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Scratchbox 2 in simple terms?

Why does Scratchbox 2 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Scratchbox 2?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Scratchbox 2.