Subject: Re: CCL:G:Alpha + Linux ?

From: Jussi Eloranta <[email-masked]>
Date: Sun, 3 Aug 1997 11:31:59 +0300 (EET DST)

>If you're doing Fortran development it has to be mentioned that the
>GNU Fortran Compiler g77 isn't yet ported to Linux Alpha. There was a
>successful call for donations on the Alpha-Linux mailinglists for
>buying an Alpha machine for the main g77-developper Craig
>Burley. Since Craig is using the Alpha now as main development
>platform most of the port has been done these days but it isn't
>finished.

Last time I checked the g77 already contained patches for 64 bit
systems (esp. alpha) but I am not sure if it still was stable or not.

One thing is that I think that alpha and intel linux systems still use
different C libraries. There will be unification at some point to the
gnu C library but until then there are some differences in the source
code level.

>The last major disadvantage of Linux on the Alpha platform is a linker
>bug which prevents building large binaries (as far as I know, this is
>why Gaussian hasn't been ported to Linux until now).

Is this fixed now? If not are there details on this anywhere?

>But: if you have a Digital Unix license you can compile your programs on
>a machine running Digital Unix and execute them on the Linux one. This
>way you get the advantages of both worlds.
>

At least I had problems with the licensing stuff when I tried to run
OSF binaries on linux. Especially the libdxml uses licensing and
what's worst it uses threads. I heard that the libdxml can be replaced
by some freely available one and the problems are gone. One interesting
option is offered by digital where one can run linux/intel binaries
on linux/alpha. This is based on their technology which they use on
NT. This emulation package is free at least for linux. It would be interesting
to see how fast the emulation runs (there has been some very impressive
benchmarking results with the windows applications).

Once the g77 runs then linux/alpha will be, IHMO, *very* attractive
platform for comp. chem. (= cheap & good & fast)

Regards,

Jussi Eloranta

---

From: Markus Dickebohm <[email-masked]>
Date: 03 Aug 1997 11:50:15 +0200

>> Jussi Eloranta schrieb am Sun, 3 Aug 1997 11:31:59 +0300 (EET DST):

> systems (esp. alpha) but I am not sure if it still was stable or not.

As I mentioned, the port is in progress. Some people reported that they
got it running, but there are still some problems remaining. In the
current stadium I wouldn't recommend using it as a main development
platform, but this should change with the next release of g77.

> One thing is that I think that alpha and intel linux systems still
> use different C libraries. There will be unification at some point
> to the gnu C library but until then there are some differences in
> the source code level.

Alpha Linux already uses the Gnu C-library (a.k.a. libc6). This will
be the library that Linux Intel is moving to in the next step. There
are differences but porting C programs to Linux Alpha is not a big
deal. Almost any major package runs fine.

> Is this fixed now? If not are there details on this anywhere?

The developers are working on this problem but it isn't fixed at the
moment in the main distribtions.  The best source of informations
about Linux-Alpha is the brand new newsgroup "comp.os.linux.alpha".

> One interesting option is offered by digital where one can run
> linux/intel binaries on linux/alpha. This is based on their
> technology which they use on NT. This emulation package is free
> at least for linux. It would be interesting to see how fast the
> emulation runs (there has been some very impressive benchmarking
> results with the windows applications).

I could do some benchmarks if there is enough interest but I would not
really recommend using this option for computational chemistry.  It has
to be considered that the FX!32 technology on NT has a major advantage
against the EM86 package: there is an incremental translator in the FX!32
package which does a binary translation of Intel code which results in
much better performance for future runs of the same problem.  Jim Paradis
(the main developer at DEC) writes:

  EM86 is based on the x86 execution engine from FX!32 (which is
  written entirely in assembler and is VERY carefully hand-tuned to
  achieve optimum performance on Alpha), but I do not intend to
  implement the incremental translator

> platform for comp. chem. (= cheap & good & fast)

I absolutely agree.

Markus

-- 
Markus Dickebohm        E-Mail: [email-masked]
Physical Chemistry      
University of Cologne
Germany