Re: [PATCH, libjava/classpath]: Fix overriding recipe for target 'gjdoc' build warning

[Jeff Law <law at redhat dot com>]

On 08/20/2015 10:03 AM, Andrew Hughes wrote:
> ----- Original Message -----
> > On 08/20/2015 09:27 AM, Andrew Haley wrote:
> > > On 08/20/2015 03:57 PM, Andrew Hughes wrote:
> > > > ----- Original Message -----
> > > > > On 20/08/15 09:24, Matthias Klose wrote:
> > > > > > On 08/20/2015 06:36 AM, Tom Tromey wrote:
> > > > > > > Andrew> No, it isn't. It's still a necessity for initial bootstrapping
> > > > > > > of
> > > > > > > Andrew> OpenJDK/IcedTea.
> > > > > > >
> > > > > > > Andrew Haley said the opposite here:
> > > > > > >
> > > > > > > https://gcc.gnu.org/ml/gcc-patches/2015-08/msg00537.html
> > > > > >
> > > > > > if you need bootstrapping OpenJDK 6 or OpenJDK 7, then having gcj
> > > > > > available for the target platform is required. Starting with OpenJDK
> > > > > > 8 you should be able to cross build OpenJDK 8 with an OpenJDK 8
> > > > > > available on the cross platform.  It might be possible to cross
> > > > > > build older OpenJDK versions, but this usually is painful.
> > > > >
> > > > > Sure, but we don't need GCJ going forward.  I don't think that there
> > > > > are any new platforms to which OpenJDK has not been ported which will
> > > > > require GCJ to bootstrap.  And even if there are, anybody who needs to
> > > > > do that can (and, indeed, should) use an earlier version of GCJ.  It's
> > > > > not going to go away; it will always be in the GCC repos.  And because
> > > > > newer versions of GCC may break GCJ (and maybe OpenJDK) it makes more
> > > > > sense to use an old GCC/GCJ for the bootstrapping of an old OpenJDK.
> > > >
> > > > I don't see how we don't at present. How else do you solve the
> > > > chicken-and-egg situation of needing a JDK to build a JDK? I don't
> > > > see crossing your fingers and hoping there's a binary around
> > > > somewhere as a very sustainable system.
> > >
> > > That's what we do with GCC, binutils, etc: we bootstrap.
> > Right.  So the question is there some reason why OpenJDK can't be used
> > to bootstrap itself?  Ie, is there a fundamental reason why Andrew needs
> > to drop back down to GCJ and start the bootstrapping process from scratch.
> >
> > ISTM that ideally the previous version of OpenJDK would be used to
> > bootstrap the new version of OpenJDK.
> >
> > Which leaves the question of how to deal with new platforms, but it
> > sounds like there's a cross-compilation process starting with OpenJDK 8
> > which ought to solve that problem.
>
> The issue is that we're still supporting a version of OpenJDK/IcedTea where
> there is no previous version (6). Once that goes, gcj could go too. This
> is still just a little too soon.
But surely OpenJDK6 can build OpenJDK6, right?  I don't see you're 
fundamentally getting anything from always starting with a GCJ bootstrap.

> That's where it comes unstuck. How do you get a JDK built when there are
> no JDK binaries for your architecture?
Cross compilation, just like folks do for Ada.


> >
>
> I'm not against this long-term, just not immediately. Deprecating it now
> and removing it in the next release cycle (7?) would probably be enough,
> but we need a little more time to wind down dependencies. I don't see us
> needing it in a GCC released in 2017.
I was of the opinion that we should remove it from the default languages 
to be built.  Others wanted to be more aggressive :-)

jeff