File.........: 5 - Using the toolchain.txt

 Copyrigth....: (C) 2010 Yann E. MORIN <yann.morin.1998@anciens.enib.fr>

 License......: Creative Commons Attribution Share Alike (CC-by-sa), v2.5

 Using the toolchain  /

 ____________________/

 Using the toolchain is as simple as adding the toolchain's bin directory in

 your PATH, such as:

   export PATH="${PATH}:/your/toolchain/path/bin"

 and then using the target tuple to tell the build systems to use your

 toolchain:

   ./configure --target=your-target-tuple

 or

   make CC=your-target-tuple-gcc

 or

   make CROSS_COMPILE=your-target-tuple-

 and so on...

 It is strongly advised not to use the toolchain sys-root directory as an

 install directory for your programs/packages. If you do so, you will not be

 able to use your toolchain for another project. It is even strongly advised

 that your toolchain is chmod-ed to read-only once successfully build, so that

 you don't go polluting your toolchain with your programs/packages' files.

 Thus, when you build a program/package, install it in a separate directory,

 eg. /your/root. This directory is the /image/ of what would be in the root file

 system of your target, and will contain all that your programs/packages have

 installed.

 The 'populate' script |

 ----------------------+

 When your root directory is ready, it is still missing some important bits: the

 toolchain's libraries. To populate your root directory with those libs, just

 run:

   your-target-tuple-populate -s /your/root -d /your/root-populated

 This will copy /your/root into /your/root-populated, and put the needed and only

 the needed libraries there. Thus you don't polute /your/root with any cruft that

 would no longer be needed should you have to remove stuff. /your/root always

 contains only those things you install in it.

 You can then use /your/root-populated to build up your file system image, a

 tarball, or to NFS-mount it from your target, or whatever you need.

 The populate script accepts the following options:

  -s src_dir

     Use 'src_dir' as the un-populated root directory.

  -d dst_dir

     Put the populated root directory in 'dst_dir'.

  -l lib1 [...]

     Always add specified libraries.

  -L file

     Always add libraries listed in 'file'.

  -f

     Remove 'dst_dir' if it previously existed; continue even if any library

     specified with -l or -L is missing.

  -v

     Be verbose, and tell what's going on (you can see exactly where libs are

     coming from).

  -h

     Print the help.

 See 'your-target-tuple-populate -h' for more information on the options.

 Here is how populate works:

   1) performs some sanity checks:

      - src_dir and dst_dir are specified

      - src_dir exists

      - unless forced, dst_dir does not exist

      - src_dir != dst_dir

   2) copy src_dir to dst_dir

   3) add forced libraries to dst_dir

      - build the list from -l and -L options

      - get forced libraries from the sysroot (see below for heuristics)

        - abort on the first missing library, unless -f is specified

   4) add all missing libraries to dst_dir

      - scan dst_dir for every ELF files that are 'executable' or

        'shared object'

      - list the "NEEDED Shared library" fields

        - check if the library is already in dst_dir/lib or dst_dir/usr/lib

        - if not, get the library from the sysroot

          - if it's in sysroot/lib, copy it to dst_dir/lib

          - if it's in sysroot/usr/lib, copy it to dst_dir/usr/lib

          - in both cases, use the SONAME of the library to create the file

            in dst_dir

          - if it was not found in the sysroot, this is an error.