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Re: Concerns about AMD64 port

On Thu, Feb 05, 2004 at 10:17:11AM -0500, Stephen Frost wrote:
> * John Goerzen (jgoerzen@complete.org) wrote:
> > Like I mentioned, there is not much manual effort here; most software is
> > already 64-bit clean.
> Eh, there's been comments that, while most of it compiles, alot of it
> doesn't run as well as it should because it hasn't been tested nearly as
> much.  I've got no personal experiance on this, perhaps you do (sounds
> like it considering you had a 64bit alpha system previously).

I can state that I absolutely believe that running as a pure 64-bit
platform should not cause concerns about stability.  Here's why:

Yes.  I still have the Alpha, and it will be my primary desktop machine
for another couple of weeks :-)  It has been used variously as
everything from a workstation to a server.  I at one time ran the Alpha
autobuilder before we had an official build infrastructure, so I have
some experience on what builds and what doesn't.  Most is fine.

Alpha was the first 64-bit platform supported by Linux (or, to my
knowledge, any other free OS).  The Alpha has no 32-bit mode at all.  It
is also picky about things like alignment.  Therefore, if things are
going to break because of being 64-bit, they would likely have broken on
Alpha.  Few did.

There are, of course, applications that have not run properly out of the
box, and for about the first year after I got the Alpha (which was back
in 1997 or so), I was involved with fixing these programs.  However, by
and large, those fixes that were applied on the Alpha also fix the same
problems for the Itanium, Sparc64, and AMD64; my understanding is that
the Alpha is actually more picky about things such as alignment than
these other archs.

At the present time, I have trouble on the Alpha with only two apps:
konqueror and openoffice.  Konqueror may be a problem unrelated to
porting.  OpenOffice is rumored to not be 64-bit clean right now, but
the OO.o people are apparently hard at work fixing this.  Fixing it for
one arch should get it fixed for all.

Alpha has been a stable, released Debian architecture for some years
now; it was first an officially released arch with slink (2.1).  I do
not have fears that any random package I install will have 64-bit
issues.  The occasional 64-bit issue does still crop up, but by and
large, it is quite rare today.  64-bit platforms have been a part of
Linux for a *long* time.  Linux supports five different 64-bit platforms
(Alpha, IA-64, AMD64, PPC64, and Sparc64); Debian has ports in-tree for
Alpha and IA-64, with Alpha having been officially released almost five
years ago and in-tree for at least seven years (not sure exactly when
that happened).

Other operating systems that pretty much the same apps in userland as we
do also support 64-bit platforms.  The best example is NetBSD, which
supported a pure 64-bit userland beginning in 1995 with the release of
NetBSD 1.1 with Alpha supprt (yes, that is almost a decade now of a pure
64-bit userland supported for production environments).  DEC's versions
of Unix, of course, predate even that.

What I'm trying to say here is that *nix apps have a *long* history of
running on pure 64-bit platforms.  There has also been a long time for
people to discover and remove 64-bit bugs and for developers to get
educated about what not to do.

I am, therefore, totally unconvinced by the argument that a 64-bit AMD64
platform will inevitably be less stable than a 32-bit one.  My
experience in this area suggests otherwise.

(Incidentally, I also work with PowerPC machines, which are 32-bit but
big-endian [Alpha is 64-bit, little endian].  I have found problems even
more rare there than on Alpha.)

As it should be, if you were to sit down at my Alpha and start using the
system, you would have no idea that you were not using a PC unless you
poked around in /proc or something.  It uses PCI, an ATX form factor,
and all the same apps that I use on my x86 hardware run on the Alpha.  I
run a Samba server, encode MP3s, watch video, run a name server, browse
the Web, hack on Debian, use LVM and RAID, etc.  It's all there.

> It's the package system, from only doing 32bit or 64bit to being able to
> support both 32bit and 64bit on a single system and have the packaging
> system handle it decently.

Yes, and from the recent flamage on debian-devel with no clear
conclusion, it looks like the package system is not going to be fixed
any time soon.  Especially since people don't agree on what that fix
should be.

-- John

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