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Re: Results of the meeting in Helsinki about the Vancouver proposal

> > > * By using a cross-compiler, by definition you use a compiler that is
> > >   not the same as the default compiler for your architecture. As such,
> > >   your architecture is no longer self-hosting. This may introduce bugs
> > >   when people do try to build software for your architecture natively
> > >   and find that there are slight and subtle incompatibilities.
> > > 
> > 
> > I have never seen nor heared about such a case. IME this is extremely
> > rare (if it happens at all).
> Do you want to take the chance of finding out the hard way after having
> built 10G (or more) worth of software?

I don't see why the risk would be higher compared to native compilation.

> This is not a case of embedded software where you cross-compile
> something that ends up on a flash medium the size of which is counted in
> megabytes; this is not a case of software which is being checked and

Some embedded software is fairly extensive and runs from HD.

> tested immediately after compilation and before deployment. This is a

Most packages are not tested automatically at all.

> whole distribution. Subtle bugs in the compiler may go unnoticed for a
> fair while if you don't have machines that run that software 24/7. If

Only a very tiny fraction of the software in debian runs 24/7 on debian

> you replace build daemons by cross-compiling machines, you lose machines
> that _do_ run the software at its bleeding edge 24/7, and thus lose
> quite some testing. It can already take weeks as it is to detect and

Most cross compiled software also runs 24/7. I have yet to see problems
produced by cross compiling the code.

> track down subtle bugs if they creep up in the toolchain; are you
> willing to make it worse by delaying the time of detection like that?

They wouldn't necessarily show up any faster in native builds. 

> I'm not saying this problem is going to hit us very often. I do say this
> is going to hit us at _some_ point in the future; maybe next year, maybe
> in five years, maybe later; in maintaining autobuilder machines over the
> past four years, I've seen enough weird and unlikely problems become
> reality to assume murphy's law holds _quite_ some merit here. The
> important thing to remember is that this is a risk that is real, and
> that should be considered _before_ we blindly switch our build daemons
> to cross-compiling machines.

I don't think the risk is real considering the amount of cross compiled
software already running in the world.


Peter (p2).

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