automake dependency tracking was Re: Automatic Re-Building ofBSP

[Joel Sherrill]

Ralf Corsepius wrote:
> 
> Am Don, 2003-02-06 um 15.18 schrieb Joel Sherrill:
> > Ralf Corsepius wrote:
> > >
> >
> > > [2] I had wanted to replace "make depend" by automake-dependency
> > > tracking, but somebody at OAR had decided to reject this proposal, due
> > > to other implications/side-effects this step would imply. :-(
> >
> > I have a suspicion that "someone at OAR" must be me
> Who else? ;)

:)  I'm fast and vocal. :)

> > but I swear I don't remember this at all.
> 
> In brief:
> 
> Not being able to apply automake dependency tracking is a direct
> consequence of you not wanting to (at least temporarily) abandon RTEMS
> build-variants.

I suspected it would be a consequence of that or something else.  OK
we have established that profile is non-functional and that even if it
worked it isn't even functionally different from the other variants.

So how would we build _g versions of the tree?  I apologize because you
have explained this before.  

Then you know my next question.  If we abandon them in the tree, is it
possible to keep the DEBUG variant visible from the application Makefile
perspective?

> Long version:
> 
> Automake compilation rules generate dependencies "on-the-fly" when
> compiling a source file, transparently using automake's depcomp script
> instead of directly using CC. The details of this kind of dependency
> tracking is rather complicated and requires a fairly complicated
> infrastructure inside of each Makefile, which is hardly maintainable
> manually, esp. because automake can generate them automatically if using
> automake-compilation rules.
> 
> I.e. the essential step to apply automake dependency-tracking in a
> simple manner would be to apply automake-compilation rules.
> The easiest way to achieve this is to apply automake to compilation,
> instead of using custom rules, as we now do.
> 
> At present time, RTEMS build variants (debug, optimize, profile) prevent
> being able to implement this.
> 
> I.e. with you having rejected my proposal to abandon build-variants,
> applying automake dependency tracking has become very hard, at least has
> reached a complexity I do not want to deal with.

GIven that I am about to fork a branch, it is time to revisit this.

> BTW: The tools/ and the doc/ subdirectories in RTEMS source-tree apply
> vanilla automake compilation rules and automake-dependency tracking.
> 
> Ralf

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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