Re: why build start files before core gcc pass 2 ?

["Yann E. MORIN" <yann dot morin dot 1998 at free dot fr>]

Esben, All,

On Tuesday 26 February 2013 Esben Haabendal wrote:
> "Yann E. MORIN" <yann.morin.1998@free.fr> writes:
> > On Thursday 17 January 2013 Wang Baisheng wrote:
[--SNIP--]
> >> If above is true, the question is transfered to : why need  a
> >> shared-capable core gcc to build NPTL ?
> >
> > This is a very complex question, for which I do not have the absolute
> > answer.
> >
> > There are two ways to approach this problem: the academic point of view,
> > and the pragmatic point of view.
> >
> > First, the pragmatic view point: everybody does it this way: crosstool-NG
> > openembedded, buildroot, all major distros... So it is a known way of
> > having an NPTL toolchain, with no need to have to solve new issues no one
> > will really be interested to investigate, as a working solution already
> > exists.
> >
> > That's probably not a satisfiable answer for some, but as it does get the
> > job done, most of us are just happy with that.
> >
> > Now, from the academic stand point. NPTL is partly implemented by the
> > kernel, by the C library, and by the compiler. How these play together
> > is a bit obscur to me.
> 
> So if everybody else does something slightly wrong, we will do the same
> ;-)

Yes. This is the pragmatic approach.

However, if any one comes up with a way to build NPTL, that does involve
only two gcc steps, and is *sane*, then I'm not against integrating it.
It should however be proven to be sound beyond any doubt, though.

> FWIW, long ago I refactored the OpenEmbedded gcc and glibc recipes to
> get rid of this additional step when doing NPTL.  And it worked fine.
> Unfortunately, the work was never merged. As I remember it, based on the
> same arguments of people not really understanding.

Yes, NPTL is a complex matter, and I never said I did understand
everything NPTL. The code is as-is today because it is the way it was
done in the original crosstool. Since it is working, there is no reason
from my point of view to fix it, as it's not broken.

> I think it would be interesting if we could try to see if ct-NG could
> get this done right.  It should save other people from spending time
> trying to figure out why this is so :-)

Well, I'll expect a very strong proof such a change is sound.

For now, it is possible to add additional explanations in the doc.

Regards,
Yann E. MORIN.

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