Re: ppc64 port

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Tue, 2004-04-27 at 23:36, Cajus Pollmeier wrote:
> Hi!
> 
> Just a simple query... I _may_ have a chance to get a ppc64
> machine. Is anyone interested in such a port?
> 
> I know that it basically works with the 32 bit binaries, but the
> installation is non trivial right now and having no 64 bit code
> isn't optimal, too.

Well, the later is not true. 32 bits code tend to run faster than 64 
bits code on ppc64. Unlike amd64 where you win by having access to more
registers, on ppc64, you just end up having to use more instructions to
load a full constant in a register ;)

Overall, we can go the gentoo way, and do a full 64 bits debian
distribution independant from the 32 bits one, or we can simply do like
other distributions do, and I think it makes some sense, is to have a biarch
distribution.

The main lot of packages stays 32 bits. But we need a biarch gcc and the 2
libcs. Then, for each libxxxx package, we can build both the ppc and the ppc64
deb and they can be both installed at the same time.

But the first thing to have is a 64 bits kernel. That we really want. For
that, we need to be able to build it. So the first thing that need to be done
is to have a biarch toolchain. gcc 3.4 can be compiled biarch, but doing the
"initial" biarch build is very difficult. Once you already have the 2 glibcs
installed, it's simply a matter of rebuilding each bit normally, but if you
don't, the initial "bootstrap" is a can of worm.

So somebody should take the time into doing that, producing .deb's that can
be installed, and once they are installed, it's easy to rebuild & update to
later versions etc...

(glibc cannot easily be cross-compiled/bootstraped, this is the root of
the problem, the glibc maintainer doesn't consider that as an important
feature).

Ben.