www/faq.html - third_party/toybox - Git at Google

 <html><head><title>toybox news</title>
 <!--#include file="header.html" -->

 <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>

 <!--#include file="footer.html" -->
	<html><head><title>toybox news</title>
	<!--#include file="header.html" -->

	<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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