[Buildroot] [PATCH v2 2/3] package: fix generic extract target for top-level parallel make

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Dear Arnout Vandecappelle,

On Wed, 21 Aug 2013 21:24:19 +0200, Arnout Vandecappelle wrote:

>   On second observation, I don't really like this change, because it 
> makes the extract and patch parts asymmetrical with the others. I would 
> prefer one patch that changes it for all the targets. But then, the 
> behaviour does change, because rebuilding one package will also trigger a 
> rebuild of the packages that depend on it. Which may be a good thing, of 
> course...

When I did some experiments on top-level parallel build some years ago,
it is also one of the problem I had seen. Today, if you decide to
rebuild "libfoo", it rebuilds libfoo only and that's it. If libfoo is
used by something else, it's your responsibility to rebuild this
something else. Of course, this is all possible because the chain of
dependencies uses virtual targets and not stamp files.

If we use stamp files directly for the dependencies between the build
steps, then rebuilding a package will automatically rebuild all its
reverse dependencies. I believe this will be very very annoying for
people who just want to test a small change in a library, for example,
and make the whole OVERRIDE_SRCDIR thing used for development quite
useless.

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com