path: root/docs/busybox.net/FAQ.html

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<h3>Frequently Asked Questions</h3>

This is a collection of some of the more frequently asked questions
about BusyBox.  Some of the questions even have answers. If you
have additions to this FAQ document, we would love to add them,

<ol>
<li><a href="#kernel">Which Linux kernel versions are supported?</a>
<li><a href="#arch">Which architectures does BusyBox run on?</a>
<li><a href="#libc">Which C libraries are supported?</a>
<li><a href="#commercial">Can I include BusyBox as part of the software on my device?</a>
<li><a href="#bugs">I think I found a bug in BusyBox!  What should I do?!</a>
<li><a href="#job_control">Why do I keep getting "sh: can't access tty; job control
	turned off" errors?  Why doesn't Control-C work within my shell?</a>
<li><a href="#getting_started">How can I get started using BusyBox?</a>
<li><a href="#demanding">I demand that you to add &lt;favorite feature&gt; right now!   How come
	you don't answer all my questions on the mailing list instantly?  I demand
	that you help me with all of my problems <em>Right Now</em>!</a>
<li><a href="#helpme">I need help with BusyBox!  What should I do?</a>
<li><a href="#contracts">I need you to add &lt;favorite feature&gt;!  Are the BusyBox developers willing to
	be paid in order to fix bugs or add in &lt;favorite feature&gt;?  Are you willing to provide
	support contracts?</a>
<li><a href="#external">Where can I find other small utilities since busybox does not include the features I want?</a></li>
<li><a href="#support">I think you guys are great and I want to help support your work!</a>
<li><a href="#optimize">I want to make busybox even smaller, how do I go about it?</a>



</ol>


<hr />
<p>
<h2><a name="kernel">Which Linux kernel versions are supported?</a></h2>
<p>


    Full functionality requires Linux 2.2.x or better.  A large fraction of the
    code should run on just about anything.  While the current code is fairly
    Linux specific, it should be fairly easy to port the majority of the code
    to support, say, FreeBSD or Solaris, or Mac OS X, or even Windows (if you
    are into that sort of thing).


<hr />
<p>
<h2><a name="arch">Which architectures does BusyBox run on?</a></h2>
<p>


    BusyBox in general will build on any architecture supported by gcc.
    Kernel module loading for 2.2 and 2.4 Linux kernels is currently
    limited to ARM, CRIS, H8/300, x86, ia64, x86_64, m68k, MIPS, PowerPC,
    S390, SH3/4/5, Sparc, v850e, and x86_64 for 2.4.x kernels.

    With 2.6.x kernels, module loading support should work on all architectures.


<hr />
<p>
<h2><a name="libc">Which C libraries are supported?</a></h2>
<p>


    uClibc and glibc are supported.  People have been looking at newlib and
    dietlibc, but they are currently considered unsupported, untested, or
    worse.  Linux-libc5 is no longer supported.  If you require a small C
    library, you should probably use uClibc.


<hr />
<p>
<h2><a name="commercial">Can I include BusyBox as part of the software on my device?</h2>

    Yes.  As long as you <a href="http://busybox.net/license.html">fully comply
    with the generous terms of the GPL BusyBox license</a> you can ship BusyBox
    as part of the software on your device.

    <br>
    <a href="#support">Please consider sharing some of the money you make.</a>


<hr />
<p>
<h2><a name="bugs">I think I found a bug in BusyBox!  What should I do?</h2>
<p>


<p>

    If you simply need help with using or configuring BusyBox, please submit a
    detailed description of your problem to the BusyBox mailing list at <a
    href="mailto:busybox@mail.busybox.net"> busybox@mail.busybox.net</a>.
    Please do not send private email to Erik (the maintainer of BusyBox) asking
    for private help unless you are planning on paying for consulting services.
    When we answer questions on the BusyBox mailing list, it helps everyone,
    while private answers help only you...

    <p>

    The developers of BusyBox are busy people, and have only so much they can
    keep in their brains at a time.  As a result, bug reports sometimes get
    lost when posted to the mailing list.  To prevent your bug report from
    getting lost, if you find a bug in BusyBox, please use the <a
    href="http://bugs.busybox.net/">BusyBox Bug and Patch Tracking System</a>
    to submit a detailed bug report.

    <p>

    The same also applies to patches... Regardless of whether your patch is a
    bug fix or adds shiney new features, please post your patch to the <a
    href="http://bugs.busybox.net/">BusyBox Bug and Patch Tracking System</a>
    to make certain it is properly considered.


<hr />
<p>
<h2><a name="job_control">Why do I keep getting "sh: can't access tty; job control
	turned off" errors?  Why doesn't Control-C work within my shell?</a></h2>
<p>

    Job control will be turned off since your shell can not obtain a controlling
    terminal.  This typically happens when you run your shell on /dev/console.
    The kernel will not provide a controlling terminal on the /dev/console
    device.  Your should run your shell on a normal tty such as tty1 or ttyS0
    and everything will work perfectly.  If you <em>REALLY</em> want your shell
    to run on /dev/console, then you can hack your kernel (if you are into that
    sortof thing) by changing drivers/char/tty_io.c to change the lines where
    it sets "noctty = 1;" to instead set it to "0".  I recommend you instead
    run your shell on a real console...


<hr />
<p>
<h2><a name="getting_started">How can I get started using BusyBox?</a></h2>
<p>

    An easy method to build your own basic BusyBox based system, is to
    follow these simple steps:
    <ul>
	<li> Point your web browser <a href="http://buildroot.uclibc.org/">here</a>
	<li> Download a copy of buildroot
	<li> Unpack the tarball on your Linux system somewhere
	<li> run 'make' and configure things to taste.
	<li> run 'unset CC'.   Some Linux systems (i.e. Gentoo) set 'CC'
	    in the system environment which messes up cross compiles.
	<li> run 'make'
	<li> go have lunch, drink a pop, call a friend, play a video game, etc
		till it finishes downloading software and compiling things.
	<li> You should now have a shiny new BusyBox based system.
    </ul>


<hr />
<p>
<h2><a name="demanding">I demand that you to add &lt;favorite feature&gt; right now!   How come
	you don't answer all my questions on the mailing list instantly?  I demand
	that you help me with all of my problems <em>Right Now</em>!</a></h2>
<p>

    You have not paid us a single cent and yet you still have the product of
    many years of our work.  We are not your slaves!  We work on BusyBox
    because we find it useful and interesting.  If you go off flaming us, we
    will ignore you.


<hr />
<p>
<h2><a name="helpme">I need help with BusyBox!  What should I do?</a></h2>
<p>

    If you find that you need help with BusyBox, you can ask for help on the
    BusyBox mailing list at busybox@mail.busybox.net.  In addition to the BusyBox
    mailing list, Erik (andersee), Manuel (mjn3) and others are known to hang out
    on the uClibc IRC channel: #uclibc on irc.freenode.net.

    <p>

    <b>Please do not send private email to Erik, Manuel, or the other BusyBox
    contributors asking for private help unless you are planning on paying for
    consulting services.</b>

    <p>

    When we answer questions on the BusyBox mailing list, it helps everyone
    since people with similar problems in the future will be able to get help
    by searching the mailing list archives.  Private help is reserved as a paid
    service.  If you need to use private communication, or if you are serious
    about getting timely assistance with BusyBox, you should seriously consider
    paying for consulting services.

    <p>



<hr />
<p>
<h2><a name="contracts">I need you to add &lt;favorite feature&gt;!  Are the BusyBox
	developers willing to be paid in order to fix bugs or add in &lt;favorite feature&gt;?
	Are you willing to provide support contracts?</a></h2>
<p>

    Sure!  Now you have our attention!  What you should do is contact <a
	href="mailto:andersen@codepoet.org">Erik Andersen</a> of <a
	href="http://codepoet-consulting.com/">CodePoet Consulting</a> to bid
    on your project.  If Erik is too busy to personally add your feature, there
    are many other active BusyBox contributors who will almost certainly be able
    to help you out.  Erik can contact them privately, and may even let you to
    post your request for services on the mailing list.


<hr />
<p>
<h2><a name="external">Where can I find other small utilities since busybox 
	does not include the features I want?</a></h2>
<p>
	We maintain such a <a href="tinyutils.html">list</a> on this site!


<hr />
<p>
<h2><a name="support">I think you guys are great and I want to help support your work!</a></h2>
<p>

    Wow, that would be great!  If you would like to make a donation to help
    support BusyBox, and/or request features, you can click here:

    <!-- Begin PayPal Logo -->
    <center>
    <form action="https://www.paypal.com/cgi-bin/webscr" method="post">
	<input type="hidden" name="cmd" value="_xclick">
	<input type="hidden" name="business" value="andersen@codepoet.org">
	<input type="hidden" name="item_name" value="Support BusyBox">
	<input type="hidden" name="image_url" value="http://codepoet-consulting.com/images/codepoet.png">
	<input type="hidden" name="no_shipping" value="1">
	<input type="image" src="images/donate.png" name="submit" alt="Make donation using PayPal">
    </form>
    </center>
    <!-- End PayPal Logo -->

    If you prefer to contact Erik directly to make a donation, donate hardware,
    request support, etc, you can contact
    <a href="http://codepoet-consulting.com/">CodePoet Consulting</a> here.
    CodePoet Consulting can accept both Visa and MasterCard for those that do not
    trust PayPal...

<hr />
<p>
<h2><a name="optimize">I want to make busybox even smaller, how do I go about it?</a></h2>
<p>
	To conserve bytes it's good to know where they're being used, and the
	size of the final executable isn't always a reliable indicator of
	the size of the components (since various structures are rounded up,
	so a small change may not even be visible by itself, but many small
	savings add up).
</p>
<p>
	To examine a busybox binary with an eye to saving bytes, build an
	optimized debug version and run the "nm" command against it, like so:
</p>
<p>
	make clean && make STRIPCMD=/bin/true && nm --size-sort busybox
</p>
<p>
	This gives a list of symbols and the amount of space allocated for
	each one, sorted by size.  (Note: do not enable CONFIG_DEBUG for this,
	as that disables compiler optimization which is great for running gdb
	but misleading when trying to figure out how much space each component
	is really using under normal circumstances.)
</p>
<hr />



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