[petsc-dev] Fwd: [petsc-users] cannot find 'libz.a' when configuring

[Matthew Knepley]

On Thu, Apr 11, 2013 at 10:39 AM, Satish Balay <balay at mcs.anl.gov> wrote:

> On Thu, 11 Apr 2013, Satish Balay wrote:
>
> > On Thu, 11 Apr 2013, Matthew Knepley wrote:
> >
> > > On Thu, Apr 11, 2013 at 10:12 AM, Satish Balay <balay at mcs.anl.gov>
> wrote:
> > >
> > > > On Thu, 11 Apr 2013, Satish Balay wrote:
> > > >
> > > > > > > > > > We have had this same discussion a million times, and we
> always
> > > > > > > > > eventually
> > > > > > > > > > get to the same answer and forget. Do we need our own
> error
> > > > message
> > > > > > > for
> > > > > > > > > > petsc-dev?
> > > > > > > > > >
> > > > > > > > > > We cannot possibly guess everything that can go wrong.
> What we
> > > > need
> > > > > > > is a
> > > > > > > > > > system
> > > > > > > > > > where the user can specify what he actually wants and we
> check
> > > > it.
> > > > > > > So,
> > > > > > > > > zlib
> > > > > > > > > > and
> > > > > > > > > > everything else are optional dependencies for hdf5. If
> > > > something is
> > > > > > > not
> > > > > > > > > > specified, it
> > > > > > > > > > fails, and the user goes back and specifies the right
> thing.
> > > > > > > > >
> > > > > > > > > Sure - but specify how? specify everything with
> > > > > > > > > --with-hdf5-lib,--with-hdf5-include options?
> > > > > > > > >
> > > > > > > > > Or somehow he knows that he has to specify
> > > > > > > > > --with-zlib-include/-with-zlib-lib options?
> > > > > > > > >
> > > > > > > >
> > > > > > > > This. It would be nice if HDF5 would tell us about its
> > > > dependencies, but
> > > > > > > if
> > > > > > > > it does not, then
> > > > > > > > the user has to, and this is our system (packages).
> > > > > > >
> > > > > > > So we would start adding zlib.py, szip.py and manymore [and
> support
> > > > > > > --download-zlib --download-szip]. And if user gets the error:
> > > > > > >
> > > > > > > --with-hdf5-dir=/foo/bar does not work.
> > > > > > >
> > > > > > > So he/she send us configure.log
> > > > > > >
> > > > > > > Then we look at it and respond saying: you need to specify
> > > > --with-zlib-dir
> > > > > > > --with-szip-dir options aswell.
> > > > > > >
> > > > > > > Does this look right?
> > > > > >
> > > > > >
> > > > > > Yes, that is what I think makes sense.
> > > > > >
> > > > > > We can always try to add another layer that 'greps' for libz in
> the
> > > > hdf5
> > > > > > error message and guesses that
> > > > > > the user forgot it, but hopefully before we get to it, a sane
> storage
> > > > > > library appears, or HDF5 gets its act
> > > > > > together.
> > > > >
> > > > > In this case - why bother with libz.py and szip.py? Why not tell
> the
> > > > > user to specify hdf5 completely with --with-hdf5-include and
> > > > > --with-hdf5-lib options?
> > > > >
> > > > > Just printing the link errors on the screen might be sufficient to
> > > > > clue in the user. Currently its hidden inside configure. [And its
> not
> > > > > clear which of the 10 tests configure did for this case should be
> > > > > printed on the screen as the appropriate message]
> > > >
> > > > I might have been the one that advocated self.needsCompression
> approach
> > > > thats
> > > > currently in configure.
> > > >
> > > > This is currently used only by hdf5.py.
> > > >
> > > > My current thought is to strip it out - and just add it to hdf5.py
> as:
> > > >
> > > >     self.liblist   =
> > > >
> [['libhdf5.a','libhdf5_hl.a'],'['libhdf5.a','libhdf5_hl.a','libz.a'],['libhdf5.a','libhdf5_hl.a','zlib.lib']]
> > > >
> > > > This would be equivalent to the current functionality - and perhaps
> > > > what was there previously - before we wanted better error messages
> and
> > > > detection of zlib. Since this is not possible anyway why bother
> > > > with the additional complexity?
> > >
> > >
> > > What is not possible? Detecting zlib? Of course this is possible, and
> we do
> > > it.
> >
> > The primary thing we need is detecting hdf5 provided by user requires
> > zlib [and or szip]. This is not poissible.
> >
> > And current code can't detect zlib anyway [outside system locations]
> > so we need libz.py to detect it better.  But whats the point of it?
> > [detecting zlib or szip via --with-zlib-dir and --with-szip-dir options?]
> >
> > When use has a mesages:
> >
> > --with-hdf5=foo/bar provides does not work
> >
> > I'd rather respond with:
> >
> > Specify hdf5 and all its dependencies correctly with
> > --with-hdf5-lib,--with-hdf5-include options.
> >
> >
> > > It is not possible to know without testing what crazy link line is
> > > required by HDF5, at least I don't know how to do that.
> >
> > yes
> >
> > > This is no way affects the utility of testing for zlib.
> >
> > But whats the point of testing for zlib - if not for hdf5? And if we
> > can't relate them automatically.
>
> I'll concede that having zlib.py szip.py will be useful if you need
> them for --download-hdf5 [either as mandatory dependencies or optonal
> dependencies].
>
> Currently --download-hdf5 isn't built with either.
>
> My contention here is - depencency management stuff in configure
> doesn't help for the optional dependencies of user installed packages
> that are specified to petsc configure with the option
> --with-package-dir


Okay, I would like to distinguish between good behavior and HDF5. If we
can ask whether the package enables it, we are fine. If there is a simple
test we can do, we are fine. What can we do for HDF5?

   Matt


>
> Satish
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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