[Openembedded-architecture] who should set default tunes?

[Mark Hatle]

On 5/1/17 5:48 PM, Denys Dmytriyenko wrote:
> On Sat, Apr 29, 2017 at 10:32:07AM -0500, Mark Hatle wrote:
>> On 4/28/17 11:47 PM, Trevor Woerner wrote:
>>> http://lists.openembedded.org/pipermail/openembedded-core/2017-March/133719.html
>>>
>>> Specifying which CPU a board uses (i.e. in BSP layer) now
>>> automatically chooses hardfp? It's always defaulted to softfp. Was
>>> there a reason softfp was the default? I was under the impression CPU
>>> tuning is a DISTRO decision, not a BSP one?
>>
>> Ultimately it is the BSP that is responsible for setting the proper default tune.
>>
>> As noted in this change though, often a BSP will pick up the default from the
>> tune file that it loads.  This is (hopefully) the BSP author intentionally
>> allowing the tune file to set the 'best default', which of course can change
>> over time.
> 
> FWIW, I went back and forth on this in TI BSP and Distro layers. For some time 
> I had our machines tuned as cortex*thf, as "the highest optimization possible" 
> was one of the requirements. But after some time I realized that package and 
> sstate re-use between platforms is more beneficial and lowered machine tunes 
> to armv7*thf. I still had to specify "thf", since there are some binary pieces 
> that are only available in "thf" form, i.e. the infamous SGX blob. I use ?= in 
> machine configs, so it's still possible to easily overwrite it...
> 

Yup, and I always tell people working on BSPs that they need to use the ?=
syntax so a user can choose to override it.   Definitely an important thing to
remember.

--Mark