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Re: Concerns about AMD64 port

* John Goerzen (jgoerzen@complete.org) wrote:
> On the AMD64 Ports page[1], it says "a pure 64bit port seems to be
> academical and of little use."  I am totally shocked by that statement.

You're not the only one, believe me.  I was too, and still don't agree
with it.

> The information I've seen suggests that the AMD64 is faster by no small
> margin when running 64-bit apps than 32-bit apps (on Linux).  Debian has

In general it is, there are specific cases where 32bit apps are faster
but there's corner cases for everything.

> The only reason I can see for even bothering to support 32-bit
> applications at all is for binary-only proprietary software.  And that
> is not such a concern; it takes all of about 10 minutes to set up a
> 32-bit chroot with debootstrap to run those things in.

I tend to agree but so far the people who have been doing much of the
amd64 work have such binary-only proprietary software that they want to
see supported directly.

> So it seems to me that the great benefit to many people of having a
> native 64-bit userland has been sacrificed for the questionable benefit
> of being able to run proprietary software without making a chroot.  I am
> still a little shocked about that.

Supporting a 64bit userland is one of the goals, of course.

> Can someone explain what is going on here?

I'll give it a shot, here's a list of some facts that may help you
understand the reasoning some have used:

1) RH/SuSe have a /lib with 32bit libraries and a /lib64 with 64bit
   libraries on their amd64 systems.
2) The FHS (I think?) and/or other standards groups are putting in their
   standards that the 32bit loader is to be at /lib/ld-linux.so and the
   64bit loader at /lib64/ld-linux-amd64.so (or whatever the specific
   names are).
3) Debian wants to be standards compliant, of course.
4) Installing 64bit libraries to /lib64 is pretty difficult just to
   begin with and have everything work under Debian with the automated
   build systems and whatnot.
5) RH/SuSe are (at least trying to) supporting mixed 32/64bit amd64
   systems, doing it on Debian would be good too.
6) Doing a 64bit-only port *now* and a mixed 32bit/64bit port *later*
   would make for a very difficult upgrade path (personally I'm inclined
   to say forget the upgrade path, make a 64bit only port *now* so
   people have a *useful* 64bit system and do the mixed stuff and tell
   people they need to reinstall if they want to go to the mixed
   system, and make it clear up front that if they do use the 64bit only
   port that they'll have to reinstall later if they want to move to the
   32/64bit mixed system).
7) There's been claims that the RM or the ftp-master or someone wouldn't
   create the amd64 directory for a 64bit only port.  No clue how
   reliable these are, people couldn't point me to specific messages in
   archives or anything, or give any better wording/reasoning than what
   I've said above.

If you've got the time/resources to do a 64bit-only port and maintain it
and can convince whomever to give you wanna-build access so that you can
keep it up with the rest of unstable I'd say go for it.  I'd even be
willing to help but I don't think I've got room to host it on a fast
connection (though others might be willing to).  I've got at least one
dual-proc amd64 system I'd be willing to help compile things for a
64bit-only amd64 port with.

I'd be happy to hear from others if my list of reasons above is
incomplete or not accurate.


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