[yocto] What are _virtual providers? and other Suffixes?

[Brad Litterell]

Paul, thanks so much! 

On Aug 21, 2013, at 7:26 AM, Paul Eggleton <paul.eggleton at linux.intel.com> wrote:

> Hi Brad,
> 
> On Tuesday 20 August 2013 23:42:36 Brad Litterell wrote:
>> Thanks - that makes it clearer.  But now I have one other question to ask:
>> 
>> if  virtual/xyz is added to overrides when the item is dealt with, then in
>> that case P_P_virtual/xyz_am335 has two overrides hanging off of the base
>> variable PREFERRED_PROVIDER.
>> 
>> You also said earlier that the latest override applies, so is there some
>> rule for multiple conditionals on a variable?
> 
> Yes, effectively all must be in OVERRIDES for the assignment statement to take 
> effect.
> 
>> E.g. What happens in a case like the following?
>> 
>> OVERRIDES="foo1:bar2:car3"
>> 
>> VARIABLE_foo1_bar2 = "both"
>> VARIABLE_car3 = "last one"
>> 
>> what does VARIABLE wind up?  The first is "more specific" in that it matches
>> two values in overrides, whereas car is last, but less specific.
> 
> I would have thought that the value would have been "last one" however 
> experimentation shows that "both" is what you actually get. I'm not exactly 
> sure why. In practice I don't think we hit this kind of situation too often 
> though, i.e. a mix of double and single overrides where the single override 
> needs to take precedence.
> 
> Cheers,
> Paul
> 
> -- 
> 
> Paul Eggleton
> Intel Open Source Technology Centre