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Subject: Re: [OMPI devel] new CRS component added (criu)
From: Jeff Squyres (jsquyres) (jsquyres_at_[hidden])
Date: 2014-02-11 15:09:35

On Feb 8, 2014, at 4:49 PM, Adrian Reber <adrian_at_[hidden]> wrote:

>> I note you have a stray $3 at the end of your configure.m4, too (it might supposed to be $2?).
> I think I do not really understand configure.m4 and was happy to just
> copy it from blcr. Especially what $2 and $3 mean and how they are
> supposed to be used. I will try to simplify my configure.m4. Is there an
> example which I can have a look at?

Sorry -- been a bit busy with releasing OMPI 1.7.4 and preparing for 1.7.5...

m4 is a macro language, so think of it as templates with some intelligence.

$1, $2, and $3 are the "parameters" passed in to the macro. So when you do something like:

   echo 1 is $1
   echo 2 is $2])

and you invoke that macro via

   FOO([hello world], [goodbye world])

the generated script will contain:

   echo 1 is hello world
   echo 2 is goodbye world

In our case, $1 is the action to execute if the package is happy / wants to build, and $2 is the action to execute if the package is unhappy / does not want to build.

Meaning: we have a top-level engine that is iterating over all frameworks and components, and calling their *_CONFIG macros with appropriate $1 and $2 values that expand to actions-to-execute-if-happy / actions-to-execute-if-unhappy.

Make sense?

>> Finally, I note you're looking for libcriu. Last time I checked with the CRIU guys -- which was quite a while ago -- that didn't exist (but I put in my $0.02 that OMPI would like to see such a userspace library). I take it that libcriu now exists?
> Yes criu has introduced libcriu with the 1.1 release. It is used to
> create RPCs to the criu process running as a service. I submitted a few
> patches to criu to actually install the headers and libraries and
> included it in the Fedora package:
> This is what I am currently using to build against criu.


I guess I should go look at that; thanks.

Jeff Squyres
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