PCYMTNQREAIYR (Was Re: cygwin packaging approach for atlas3.6 and lapack3)

Igor Pechtchanski pechtcha@cs.nyu.edu
Mon Jun 27 03:30:00 GMT 2005

On Sun, 26 Jun 2005, James R. Phillips wrote:

> --- Igor Pechtchanski  wrote:
> > <http://cygwin.com/acronyms/#PCYMTNQREAIYR>.  Thanks.
> I use web mail for my cygwin mailing list interactions, so I can access
> from work or from home.  Unfortunately, I don't see a way to configure
> this for yahoo web mail.  But I can manually fix it up, and will try to
> remember to do so.  Thanks for the reminder.

Yeah, with web mail hand-editing seems to be the only alternative.
Thanks for doing this.  FWIW, if many people request such a feature (or if
GMail introduces it), I'm sure Yahoo will give in and implement it.

I do know, however, that Yahoo mail respects the Reply-To: header --
please let it do so.  Discussions like the one below should take place on
the mailing list, so that they are in the archives.

> > Building a DLL isn't hard.  Writing a function that dlopen's a DLL and
> > checks for the return value isn't very hard either.  This isn't
> > systems-level stuff...  It all depends on the amount of time you'd like to
> > invest in this, of course.
> Fair point.  If I see a payoff, I'll investigate further.

Someone else (Bas van Gompel) just proposed a "wrap" program that does the
same for executables.  I wonder if he'd be willing (or if it's too much
effort) to extend this to DLLs...

> > This is not a question of release cycles.  If someone reinstalls the
> > current version of lapack, they'll lose the optimized atlas DLLs just
> > as surely as they would on an upgrade.  Besides, if there are
> > packaging or Cygwin-specific problems, you may want to make a few
> > Cygwin releases based on the same upstream versions of lapack/atlas,
> > which the users would have to upgrade to.
> >
> > How does the Linux version of atlas handle these issues?  Does it use
> > symlinks to shared libraries?
> The debian atlas version seems very elegant, but I haven't completely
> figured out how it works.  I don't think symlinks are involved more than
> with normal shared libraries.  [All linux shared libraries use symlinks
> from major version library names to abi compliant minor versions.  This
> allows libraries to be updated without requiring software that uses the
> libraries to be recompiled].

FWIW, Windows doesn't support anything like that.  Welcome to DLL hell.

> Basically the maintainer collected optimization-response records from
> atlas users on several archs, and feeds the responses artifically into
> the atlas optimizer, so you can compile optimized code for these archs
> without necessarily having that arch.  He maintains separate binary
> packages for several archs, and you can run the actual optimization if
> you install the source package.
> debian packaging makes cygwin packaging look extremely simple.

Good to know. :-)

> There may be a way to use symlinks with pre-install/post-install scripts
> to alleviate the problems you are identifying.  I will give that some
> thought.

As mentioned above (though not very clearly), symlinks to DLLs don't work
in Windows.  Hard links do, but those are only supported on NTFS, and an
upgrade will break them anyway.  I can't think of a way to do this without
a wrapper DLL, but that's why this should stay on the list -- perhaps
others will be able to find better solutions.
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     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski, Ph.D.
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

"The Sun will pass between the Earth and the Moon tonight for a total
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