Subject: Re: linux-next: tip-core build failure

From: Ingo Molnar <[email-masked]>
Date: Mon, 15 Sep 2008 10:11:29 +0200

* Stephen Rothwell <[email-masked]> wrote:

> Hi Ingo,
> 
> On Sun, 14 Sep 2008 21:17:09 +0200 Ingo Molnar <[email-masked]> wrote:
> >
> > * Stephen Rothwell <[email-masked]> wrote:
> > 
> > > On Sun, 14 Sep 2008 20:36:29 +0200 Ingo Molnar <[email-masked]> wrote:
> > > >
> > > > [ ... just used by 90%+ of our active testers/developers ;-) ... ]
> > > 
> > > An irrelevant argument in this case.
> > 
> > why is the actual usage distribution of Linux irrelevant? We make 
> 
> Notice the "in this case"?  In this case the code being changed 
> clearly could affect other architectures, so checking that x86 is OK 
> is clearly not enough (and that does not mean building it for 20+ 
> other architectures, just using grep to see the consequences of the 
> change and maybe discussing it with the affected architecture 
> maintainers or on linux-arch).

again, the side effects were not realized. Pretty much _any_ patch that 
is not strictly restricted to a single architecture 'could' affect other 
architectures. Any change to a common .h or .c file could do that - and 
90% of Linux's source code is in common files.

Hence your suggestion that we should have found this breakage makes no 
sense in practice as it's not reliably testable.

Yes, for things like sparseirq support we pretty much expected 
cross-arch fallout so we checked a ton of architectures. For other 
patches bugs can slip through, and that's OK as we really dont want to 
dog down pretty much every patch with the requirement to cross-build.

	Ingo