[yocto] What's up with python3

[Gary Thomas]

On 2017-06-08 13:09, Alexander Kanavin wrote:
> On 06/08/2017 10:28 AM, Gary Thomas wrote:
>> I'm building using Poky/Yocto master
>> 576821ea0a7558b626ccc87e9ae0e9ee40864956
>> and I've noticed that python3 (target) is being built for my image, but it
>> doesn't end up in the actual image.  None of my own recipes mention python3
>> at all, yet virtually every recipe that's used in the build depend on it.
>>
>> I've listed all the recipes used in my build (from bitbake -g =>
>> recipe-depends.dot)
>> and sucked out the ones that claim to depend on python3.  I don't see
>> why, for
>> example, python(2) depends on python3?
>>
>> Can someone explain this?  I've added the appropriate files to this email.
>>
>> I'm mostly curious, but also a bit concerned that my builds are doing more
>> than they need (and hence just taking longer than they might need to)
> 
> Typically for two reasons:
> 
> a) a recipe needs to execute python during build, and host python is not suitable for some reason - so native python is 
> built and used;

Not that: I filtered out all uses of python3-native - these are only *target* dependencies

> 
> b) a supplementary package needs python, while the main package does not - most often this is the -ptest package, which 
> will not end up in the image, unless you ask.

None of my recipes build -ptest stuff:
   $ find tmp/deploy/ipk/ -name "*ptest*"

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------