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

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

Wang, All,

First, asking the same question over-and-over again, on the list or by
private mail, will not make for a faster answer.

Please, be patient. If nobody answers, maybe nobody really knows.

On Thursday 17 January 2013 Wang Baisheng wrote:
> In build script gcc.sh, I found a comments:
> 
> "In case the threading model is NPTL, we need a shared-capable core gcc".
> 
> Yes, shared-capable gcc will need crt*.o, because libgcc*.so will
> linked with crt*.o. Accoring build script, in fact, the option
> "--disable-shared" is removed when building core gcc pass 2.
> 
> So if the anwser is : To support  NPTL, we need  a cross gcc with
> "--enable-shared", i.e., building libgcc_.so instead of libgcc.a.
> while linking libgcc_s.so, link editor need crt*.o, so build crt*.o
> before building core gcc pass 2 ?
> 
> 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.

Regards,
Yann E. MORIN.

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