too big binaries

[Harald Becker]

Hi Piotr !

>I compiled it in ubuntu and then libs has that size
>
>1,1M libm-2.17.so
>1,8M libc-2.17.so
>146K ld-2.17.so

add this up and sum size of your distro Busybox binary and you
get about 3 MB.

>I thought that linker take only parts from libs whose are needed.

You mix static and dynamic linking. Static linking needs the .a
libraries and include only required routines. As Busybox does
many different things it links in many functions of the C
libraries and you get a big binary with bad scaled libraries like
GNU glibc. On the other side even a 2 MB binary is less the size
you need to run the dynamically linked version. To run that
binary you need to install the .so libraries, which take around 3
MB (plus possible more required stuff).

If you want to get smaller statically linked binaries you may
have a look on different C libraries, like uClibc or musl (but
not exclusive, there may exist other working libraries). Those
libraries try to scale better on statically linked binaries.

>What can I do, what distro can I use to reduce static compiled
>busybox si ze?

It is not directly distro specific. Most well known distros
use glibc and dynamic linking. To install the full set of
programs required by the distros, you need a library whith every
whistle and bell and compatible C++ libraries. If you want to
create small statically linked binaries you need a library
optimized for that purpose, which usually fail on installation of
many higher level packages (like GUI programs).

May be you get better success using Arch Linux or other distros
optimized for embedded devices, but other distros like Ubuntu or
Gentoo also allow to install parallel extra libraries and allow
to create statically build binaries (but this my not be
considered a trivial job).

Dig into documents for tool chains, cross compiling/linking and
differences on linking statical/dynamical. This is not only
Busybox related, and no failure of the build process.

Sometimes it is easier to ask for a statically linked version for
your platform, than building it for your own. Or take a
statically linked version from a fitting distro.

--
Harald