toybox/www/faq.html

<html><head><title>toybox news</title>
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<ul>
<li><h2><a href="#capitalize">Do you capitalize toybox?</a></h2></li>
<li><h2><a href="#why_toybox">Why toybox? (What was wrong with busybox?)</a></h2></li>
<li><h2><a href="#support_horizon">Why a 7 year support horizon?</a></h2></li>
</ul>

<a name="capitalize" />
<h2>Q: Do you capitalize toybox?</h2>

<p>A: Only at the start of a sentence. The command name is all lower case so
it seems silly to capitalize the project name, but not capitalizing the
start of sentences is awkward, so... compromise. (It is _not_ "ToyBox".)</p>

<a name="why_toybox" />
<h2>Q: "Why is there toybox? What was wrong with busybox?"</h2>

<p>A: Toybox started back in 2006 when I
<a href=https://lwn.net/Articles/202106/>handed off BusyBox maintainership</a>
and <a href=http://landley.net/notes-2006.html#28-09-2006>started over from
scratch</a> on a new codebase after a
<a href=http://lists.busybox.net/pipermail/busybox/2006-September/058617.html>protracted licensing argument</a> took all the fun out of working on BusyBox.</p>

<p>Toybox was just a personal project until it got
<a href=http://landley.net/notes-2011.html#13-11-2011>relaunched
in November 2011</a> with a new goal to
<a href=http://landley.net/aboriginal/about.html#selfhost>make Android
self-hosting</a>. This involved me relicensing my own
code, which <a href=https://lwn.net/Articles/478308/>made people who had
never used or participated in the project loudly angry</a>. The switch came
after a lot of thinking <a href=http://landley.net/talks/ohio-2013.txt>about
licenses</a> and <a href=http://landley.net/notes-2011.html#21-03-2011>the
transition to smartphones</a>, which led to a
<a href=http://landley.net/talks/celf-2013.txt>2013</a>
<a href=https://www.youtube.com/watch?v=SGmtP5Lg_t0>talk</a> laying
out a strategy to make Android self-hosting using toybox. This helped
<a href=https://code.google.com/p/android/issues/detail?id=76861>bring
it to Android's attention</a>, and they
<a href=https://lwn.net/Articles/629362/>merged it</a> into Android M.</p>

<p>The answer to the second question is "licensing". BusyBox predates Android
by almost a decade but Android still doesn't ship with it because GPLv3 came
out around the same time Android did and caused many people to throw
out the GPLv2 baby with the GPLv3 bathwater.
Android <a href=https://source.android.com/source/licenses.html>explicitly
discourages</a> use of GPL and LGPL licenses in its products, and has gradually
reimplemented historical GPL components such as its bluetooth stack under the
Apache license. Similarly, Apple froze xcode at the last GPLv2 releases
(GCC 4.2.1 with binutils 2.17) for over 5 years while it sponsored the
development of new projects (clang/llvm/lld) to replace them,
implemented its SMB server from scratch to replace samba,
<a href=http://meta.ath0.com/2012/02/05/apples-great-gpl-purge/>and so
on</a>. Toybox itself exists because somebody with in a legacy position
just wouldn't shut up about GPLv3, otherwise I would probably
still happily be maintaining BusyBox. (For more on how I wound
up working on busybox in the first place,
<a href=http://landley.net/aboriginal/history.html>see here</a>.)</p>

<h2><a name="support_horizon">Q: Why a 7 year support horizon?</a></h2>

<p>A: Our <a href=http://lists.busybox.net/pipermail/busybox/2006-September/058440.html>longstanding rule of thumb</a> is to try to run and build on
hardware and distributions released up to 7 years ago, and feel ok dropping
support for stuff older than that. (This is a little longer than Ubuntu's
Long Term Support, but not by much.)</p>

<p>If a kernel or libc feature is less than 7 years old, I try to have a
build-time configure test for it and let the functionality cleanly drop out.
I also keep old Ubuntu images around in VMs and perform the occasional
defconfig build there to see what breaks. (I'm not perfect about this,
but I accept bug reports.)</p>

<p>My original theory was "4 to 5 18-month cycles of moore's law should cover
the vast majority of the installed base of PC hardware", loosely based on some
research I did <a href=http://www.catb.org/esr/halloween/halloween9.html#id2867629>back in 2003</a>
and <a href=http://catb.org/esr/writings/world-domination/world-domination-201.html#id248066>updated in 2006</a>
which said that low end systems were 2 iterations of moore's
law below the high end systems, and that another 2-3 iterations should cover
the useful lifetime of most systems no longer being sold but still in use and
potentially being upgraded to new software releases.</p>

<p>It turns out I missed industry changes in the 1990's that stretched the gap
from low end to high end from 2 cycles to 4 cycles (<a href=http://landley.net/notes-2011.html#26-06-2011>here's my writeup on that</a>; and _that_ analysis
ignored the switch from PC to smartphone cutting off the R&D air supply of the
laptop market.  Meanwhile the Moore's Law s-curve started bending
down in 2000 and these days is pretty flat: the drive for faster clock speeds
<a href=http://www.anandtech.com/show/613>stumbled</a>
then <a href=http://www.pcworld.com/article/118603/article.html>died</a>,
the subsequent drive to go wide maxed out around 4x SMP with ~2 megabyte
caches for most applications. These days the switch from exponential to
linear growth in hardware capabilities is
<a href=https://www.cnet.com/news/end-of-moores-law-its-not-just-about-physics/>common</a>
<a href=http://www.acm.org/articles/people-of-acm/2016/david-patterson>knowledge</a>.)</p>

<p>But the 7 year rule of thumb stuck around anyway: if a kernel or libc
feature is less than 7 years old, I try to have a build-time configure test
for it and let the functionality cleanly drop out. I also keep old Ubuntu
images around in VMs and perform the occasional defconfig build there to
see what breaks.</p>

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