[OE-core] Recipe versions and layer confusion

[Mark Hatle]

On 10/5/17 9:49 AM, Mike Looijmans wrote:
> I'm confused.
> 
> Layer "meta-xilinx" defines:
> 
> recipes-bsp/arm-trusted-firmware/arm-trusted-firmware_2017.1.bb
> 
> This recipe is too old for my liking, so I made a newer one in "meta-topic"
> 
> recipes-bsp/arm-trusted-firmware/arm-trusted-firmware_2017.3.bb
> 
> 
> Much to my surprise, when I build, OE picks the 2017.1 version and not the 
> 2017.3 version.

Typically the version is selected by whichever PV is 'higher'.  However there
are many ways to change this behavior.

The primary way is for a configuration file (often the machine configuration) to
defined a preferred version.  I.e.

  PREFERRED_VERSION_arm-trusted-firmware = "2017.1"

Most likely there is a line like that someone in meta-xilinx.

Additional ways would be to have a recipe define itself as never the default
version.

> bitbake-layers show-layers reveils:
> ..
> meta-xilinx           /home/mike/projects/zynq-platform/meta-xilinx  5
> meta-topic            /home/mike/projects/zynq-platform/meta-topic  6
> ..

The layer priority does not directly affect recipe selection.  It may if you
have two layers of the -same- version.

--Mark

> so that means that my meta-topic should win even if my PV were lower, right?
> 
> 
> Kind regards,
> 
> Mike Looijmans
> System Expert
> 
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