[Buildroot] how to repopulate /output/target/lib?

[Luca Ceresoli <luca@lucaceresoli.net>]

Thomas Petazzoni wrote:
> Hello Aras,
>
> Le Mon, 25 Jun 2012 12:46:50 +0100,
> Aras Vaichas <aras.vaichas@gmail.com> a ?crit :
>
>> I understand that output/staging holds all the libraries, but how do
>> the correct libraries get copied to output/target? How can I trigger
>> this action without having to do a "make clean; make"?
>
> So far, we have no supported mechanism other than "make clean; make" to
> rebuild the target root filesystem. That's part of the Buildroot
> simplicity: we don't try to support partial rebuilds, because it is
> very complicated to get 100% right, and we don't want to support
> something that is right 90% of the time, but is known to have an
> incorrect behavior 10% of the time.
>
> To answer your question, the libraries are installed in
> output/target/{usr/,}lib by:
>
>   * The toolchain installation procedure. This one depends on whether
>     you're using the internal, external or crosstool-ng backend for your
>     toolchain. This part installs the C library and related basic
>     libraries (thread, math, rt, etc.).
>
>   * The package installation steps, which should be replayed if you
>     remove .stamp_target_installed files, as you did.
>
> Basically, my suggestions to do what you're trying to do is:
>
>   * Don't use a custom skeleton, do your customization in a post-build
>     script, because it gets re-run at every build, while the skeleton
>     copy is only done once at the beginning of a clean build;
>
>   * When you make a change to a package, just remove this package build
>     directory (rm -rf output/build/<pkg>-<version>). This is generally
>     enough to check that the new installation results are correct.

Instead of `rm -rf output/build/<pkg>-<version>`, you can just do
`make <pkg>-dirclean`, which is equivalent but a bit cleaner IMHO.

>
>   * Use an external toolchain so that doing "make clean; make" is not
>     too painful.
>
>   * Ensure you have a fast enough build machine (i.e, not a slow Windows
>     laptop that runs Linux inside a VMWare)

To speed up recompilations, also enable ccache ("Enable compiler cache" in
the "Build options" menu).

Luca