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From: Philip Balister <philip@balister.org>
To: Mark Hatle <mark.hatle@windriver.com>
Cc: openembedded-core@lists.openembedded.org
Subject: Re: Enabling NEON instructions for fftw
Date: Fri, 04 Jan 2013 10:36:16 -0500	[thread overview]
Message-ID: <50E6F6F0.2070502@balister.org> (raw)
In-Reply-To: <50E5DA36.5090702@windriver.com>

On 01/03/2013 02:21 PM, Mark Hatle wrote:
> On 1/3/13 12:42 PM, Philip Balister wrote:
>> So, recent versions of fftw have NEON support for the single precision
>> build. In the poast, I just passed --enable-neon to configure or the
>> armv7a case. Now, this is not entirely correct, since some armv7a's lack
>> a NEON coprocessor.
>>
>> Does anyone have a suggestion for how to handle this better? Personally,
>> I think if you want to run fftwf without NEON, you should have your head
>> examined, but I would like to avoid generating packages that SIGILL on
>> people.
> 
> This says to me that either you need a machine specific package, or use
> an alternative architecture for that package.. (that is compatible)..
> then the package can switch neon on/off depending on arch of tuning flags.
> 
> There is an armv7a-neon tuning defined.  This enabled the TUNE_FEATURES
> of 'neon'.  So you should be able to check for that in the fftw recipe,
> and enable the --enable-neon when it's set.  (Using PACKAGECONFIG is
> likely best...)
> 
> Then you can change the DEFAULTTUNE_<recipe> = "armv7-neon" in your
> local.conf.

I really do not want to depend on users putting entries in local.conf to
obtain proper operation on a specific machine. It looks like the neon
tune is already selected for the machine I am building for.

In the end, this boils down to, do we care about supporting machines
with/without NEON from one set of packages by making ones with NEON
machine specific.

For now, I will purse the route of fftwf building with --enable if the
neon tune is available for the machine.

Philip

Philip

Philip

> 
> --Mark
> 
>> Philip
>>
>> _______________________________________________
>> Openembedded-core mailing list
>> Openembedded-core@lists.openembedded.org
>> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core
>>
> 
> 
> _______________________________________________
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> Openembedded-core@lists.openembedded.org
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> 
> 



  reply	other threads:[~2013-01-04 15:51 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-03 18:42 Enabling NEON instructions for fftw Philip Balister
2013-01-03 19:21 ` Mark Hatle
2013-01-04 15:36   ` Philip Balister [this message]
2013-01-04 15:46     ` Mark Hatle

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