One place where those options are currently documented is in config/examples/arch-cray-*, but I'm not sure if all users find those. Some simple changes to http://www.mcs.anl.gov/petsc/documentation/installation.html might help, for instance, under "Encounter Problems?" an entry could be added which says "Examine config/examples/*.py for settings which might be relevant to your system". The settings I use to build PETSc on the cray XC30 and XC40 are similar to those in the xt5 and xt6 examples, at least as far as the big gotchas are concerned. Out of curiosity, are these still relevant on current cray machines? '--COPTFLAGS=-fast -mp', '--CXXOPTFLAGS=-fast -mp', '--FOPTFLAGS=-fast -mp', On Sun, Sep 20, 2015 at 03:51:03PM -0500, Barry Smith wrote:

Satish,

We get too many mails like this, it wastes our time and their time. In config/configure.py please add checks if the machine is a cray that the user did not provide an MPI dir, and that the user did pass in

'--with-clib-autodetect=0', '--with-cxxlib-autodetect=0', '--with-fortranlib-autodetect=0',

and any other mandatory things and error out with a very useful error message telling them what options to use and not to use.

Barry

It is absurd to think that somehow Cray users will magically know to use the auto detect = 0 flag and not provide an MPI dir etc.

...

Begin forwarded message:

From: Phani Motamarri <[email protected]> Subject: [petsc-maint] Petsc configure Error on Edison on NERSC Date: September 20, 2015 at 3:39:22 PM CDT To: petsc-maint <[email protected]>

Hi,

I am trying to compile PETSc on Edison one of the NERSC clusters. However I get the following configure error "C libraries cannot directly be used from Fortran".

I am wondering if I am missing anything. I attaching configure.log with this email.

Regards Phani