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automake dependency tracking was Re: Automatic Re-Building of BSP



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? ;)

> 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. 

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.

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

Ralf