Re: Crosstool-ng always starts from the top

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

Stuart, All,

On Wednesday 31 March 2010 00:52:00 Stuart Longland wrote:
> Is there a way to convince crosstool-ng to pick up where it left off? 

This is a limitation: crosstool-NG was not designed to be restartable.

However, it appeared that debugging crosstool-NG itself was cumbersome
when a single script was modified, so a /kind of/ stop-and-restart
feature was added, that works _iff_ the configuration has not changed.

That way, I was able to try to patch gcc or it's build script and restart
again without loosing too much time.

To sum-up:
 - no, it's not possible to restart where it left off, if the
   configuration has changed
 - yes you can stop-and-restart at any place iff the configuration
   has *not* changed.

> The upshot is that I have to run `ct-ng menuconfig` again, and tweak 
> the options for gcc and run it again.  This is fine, but when I run 
> `ct-ng build`, it starts right from scratch again building GMP, MPFR, 
> PPL, Cloog and binutils... which all should be identical to before, and 
> shouldn't need rebuilding.

That's right from a theorical point of view. 

> Is there a reason why the builder can't just assume (or be convinced to 
> assume) those components are already built and resume at the last 
> component where the failure occurred?

Well, most notably a design issue. The /issue/ is that crosstool-NG has
(so far) no way to tell what changed in the configuration, related to
what component(s), and what following copmponent(s) the change does
impact.

And fixing this will need a *huge* amount of work, which I am not yet ready
to invest. Except if someone comes with a patch that I can review! ;-)

Regards,
Yann E. MORIN.

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