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Subject: Re: [OMPI devel] autoconf warnings: openib BTL
From: Jeff Squyres (jsquyres) (jsquyres_at_[hidden])
Date: 2014-03-03 10:31:14


Can't you test for that at run-time?

I.e., can't you do the configure-time test to see if AF_IB exists, and if it does, do a run-time check to see if it's useful/supported in the kernel? Or is there a reason not to do this (e.g., it would impose a performance penalty at run time because the check would need to be in the performance-critical code path)?

On Mar 2, 2014, at 11:02 PM, Vasily Filipov <vasily_at_[hidden]> wrote:

> some additional explanation - it could be a situation when AF_IB is defined in user space but kernel doesn't support it.
>
> On 03-Mar-14 08:53, Vasily Filipov wrote:
>> Hi Jeff,
>> I've committed the fixes (r30905). It is a problem to detect kernel defines (such as AF_IB ), so we have to use AC_RUN_IFELSE macro.
>>
>> Thanks,
>> Vasily.
>>
>> On 27-Feb-14 17:09, Jeff Squyres (jsquyres) wrote:
>>> I'm seeing this warning this morning:
>>>
>>> -----
>>> configure.ac:1139: warning: AC_RUN_IFELSE called without default to allow cross c\
>>> ompiling
>>> ../../lib/autoconf/general.m4:2748: AC_RUN_IFELSE is expanded from...
>>> ../../lib/m4sugar/m4sh.m4:639: AS_IF is expanded from...
>>> ompi/mca/btl/openib/configure.m4:37: MCA_ompi_btl_openib_CONFIG is expanded from.\
>>> ..
>>> config/ompi_mca.m4:571: MCA_CONFIGURE_M4_CONFIG_COMPONENT is expanded from...
>>> config/ompi_mca.m4:352: MCA_CONFIGURE_FRAMEWORK is expanded from...
>>> config/ompi_mca.m4:252: MCA_CONFIGURE_PROJECT is expanded from...
>>> config/ompi_mca.m4:39: OMPI_MCA is expanded from...
>>> configure.ac:1139: the top level
>>> -----
>>>
>>> Is it necessary to AC_RUN_IFELSE here? Is AC_CHECK_DECLS not sufficient for some reason?
>>>
>>> It strikes me that this test you currently have in configure.m4 really should be a run-time test, and that all you need in configure.m4 should be an AC_CHECK_DECLS to see if AF_IB exists.
>>>
>>
>
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-- 
Jeff Squyres
jsquyres_at_[hidden]
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