Documentation

Software requirements

Compiling uClibc-ng requires Linux kernel header files. uClibc-ng will be compiled to match the interfaces available in the provided version of the Linux kernel headers. Linux kernel versions 2.6.x/3.x/4.x are supported. Its also helpful to have a working version of GNU binutils, and GNU gcc – using excessively old versions of these packages can cause very strange errors that are difficult to find and fix.

Configuring uClibc-ng

  • Users must have a valid configuration file to compile uClibc-ng. Do not skip this step. New configuration options are added in each release, and odd configuration options are sometimes removed. To configure uClibc-ng, you can run:

        make menuconfig
    

    or make config

    If you have an existing .config file, you can update this file using the

        make oldconfig
    

    command, which will only ask you about new configuration options.

    Available configuration commands are: “make config” Text based configuration, no menus or colors. “make menuconfig” Text based color menus, radiolists & dialogs. “make oldconfig” Default all questions based on the contents of your existing ./.config file. “make defconfig” Use defaults for all options. “make randconfig” Use random values for all options. “make allyesconfig” Set all values to “yes” for all options. “make allnoconfig” Set all values to “no” for all options.

Compiling uClibc-ng

  • uClibc-ng does not have proper dependancy checking so if you change your uClibc-ng configuration, you must current rebuild the entire library, by first running

        make clean
    
  • Once you have a valid configuration file, just run

        make
    

    to compile uClibc-ng. or if you are cross compiling, you would instead run something like:

        make CROSS_COMPILE=arm-linux-
    

Installing the uClibc-ng development environment

  • As root, if necessary, run something like:

    make PREFIX=<some path> install
    

    This will install the uClibc-ng runtime and development system (i.e. all the header files, libraries, etc) into the directories defined within your .config file.

Using uClibc-ng

Internationalization support

For internationalization / localization support in open source software projects under Linux libintl is used. This means that the text output of the application might be translated to different languages. It handles both internationalization (i18n) and localization (l10n). See http://www.labri.fr/perso/fleury/posts/programming/a-quick-gettext-tutorial.html

  • uClibc-ng includes a stub implementation, you need to enable UCLIBC_HAS_LIBINTL
  • musl implements libintl
  • glibc includes the libintl library

The stub implementation included in uClibc-ng is gettext-tiny. You can use gettext with uClibc-ng systems, but need to enable locale support to have translation support on your system.

You could also use gettext: https://www.gnu.org/software/gettext

Header: libintl.h Functions: *gettext(), bindtextdomain(), textdomain()

Locale support

For a working internationalization / localization support you need locale support in your C library. The environment variables LC_ALL, LC_xxx, LANGUAGE and LANG are used to set-up the localization of the user environment.

  • uClibc-ng has experimental locale support, you need to enable UCLIBC_HAS_LOCALE
  • musl has locale support
  • glibc has locale support

Header: locale.h Functions: setlocale()/localeconv(), newlocale()/freelocale()/uselocale()/duplocale()

International conversion support

Standard programming API to convert between different character encodings. https://en.wikipedia.org/wiki/Iconv

  • uClibc-ng has basic iconv support, you need to enable UCLIBC_HAS_LIBICONV
  • musl has iconv support
  • glibc has iconv support

The iconv implementation in uClibc-ng is based on libiconv-tiny. Only conversion from and to UTF-8 are supported.

You could also use libiconv: https://www.gnu.org/software/libiconv/

Header: iconv.h Functions: iconv_open(), iconv(), iconv_close()

Internationalized domain name support

See https://en.wikipedia.org/wiki/Internationalized_domain_name

There are two different implementations for IDN under Linux. libidn and libidn2. And it seems libidn is deprecated.

The C library might provide support for IDN in getnameinfo() and getaddrinfo().

  • uClibc-ng does not support IDN
  • musl does not support IDN
  • glibc includes libidn library as an addon