* Enabling NEON instructions for fftw
@ 2013-01-03 18:42 Philip Balister
2013-01-03 19:21 ` Mark Hatle
0 siblings, 1 reply; 4+ messages in thread
From: Philip Balister @ 2013-01-03 18:42 UTC (permalink / raw)
To: openembedded-core
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.
Philip
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Enabling NEON instructions for fftw
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
0 siblings, 1 reply; 4+ messages in thread
From: Mark Hatle @ 2013-01-03 19:21 UTC (permalink / raw)
To: openembedded-core
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.
--Mark
> Philip
>
> _______________________________________________
> Openembedded-core mailing list
> Openembedded-core@lists.openembedded.org
> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Enabling NEON instructions for fftw
2013-01-03 19:21 ` Mark Hatle
@ 2013-01-04 15:36 ` Philip Balister
2013-01-04 15:46 ` Mark Hatle
0 siblings, 1 reply; 4+ messages in thread
From: Philip Balister @ 2013-01-04 15:36 UTC (permalink / raw)
To: Mark Hatle; +Cc: openembedded-core
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
>>
>
>
> _______________________________________________
> Openembedded-core mailing list
> Openembedded-core@lists.openembedded.org
> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Enabling NEON instructions for fftw
2013-01-04 15:36 ` Philip Balister
@ 2013-01-04 15:46 ` Mark Hatle
0 siblings, 0 replies; 4+ messages in thread
From: Mark Hatle @ 2013-01-04 15:46 UTC (permalink / raw)
To: Philip Balister; +Cc: openembedded-core
On 1/4/13 9:36 AM, Philip Balister wrote:
> 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.
Machine specific is one answer, but my preference is to have a neon specific
package arch selected. Looking at the definitions, my expectation is that once
the -neon version of armv7 is selected the package arch should similarly be
modified to end in "-neon".
So as long as the BSP/machine uses the neon tune, then everything should be
compiled and labeled properly.
> For now, I will purse the route of fftwf building with --enable if the
> neon tune is available for the machine.
Definitely the right way to do it, no matter how the package's arch is named.
> Philip
>
> Philip
>
> Philip
>
>>
>> --Mark
>>
>>> Philip
>>>
>>> _______________________________________________
>>> Openembedded-core mailing list
>>> Openembedded-core@lists.openembedded.org
>>> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core
>>>
>>
>>
>> _______________________________________________
>> Openembedded-core mailing list
>> Openembedded-core@lists.openembedded.org
>> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core
>>
>>
^ permalink raw reply [flat|nested] 4+ messages in thread
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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
2013-01-04 15:46 ` Mark Hatle
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