discussion of layers in dev manual uses a *really* bad example

discussion of layers in dev manual uses a *really* bad example

[Robert P. J. Day]

  more pedantry -- dev manual, section 5.1.2 talks about creating a
new layer and recommends using the meta-yocto layer.conf as a starting
point, which contains:

     # We have a conf and classes directory, add to BBPATH
     BBPATH := "${LAYERDIR}:${BBPATH}"

  the problem is that almost every other layer *appends* LAYERDIR to
BBPATH, not the other way around, so that example is spectacularly
unrepresentative.  (i'm unaware of any other layer that sets BBPATH in
that order, and i recall tom zanussi (?) explaining once why that
was.)

  perhaps a different example, and a short explanation about why the
meta-yocto layer is the exception here?

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================

Re: discussion of layers in dev manual uses a *really* bad example

[Scott Garman]

On 12/30/2012 01:45 AM, Robert P. J. Day wrote:
>
>    more pedantry -- dev manual, section 5.1.2 talks about creating a
> new layer and recommends using the meta-yocto layer.conf as a starting
> point, which contains:
>
>       # We have a conf and classes directory, add to BBPATH
>       BBPATH := "${LAYERDIR}:${BBPATH}"
>
>    the problem is that almost every other layer *appends* LAYERDIR to
> BBPATH, not the other way around, so that example is spectacularly
> unrepresentative.  (i'm unaware of any other layer that sets BBPATH in
> that order, and i recall tom zanussi (?) explaining once why that
> was.)
>
>    perhaps a different example, and a short explanation about why the
> meta-yocto layer is the exception here?

ScottR:

As some background on this issue, please take a look at this thread from 
almost exactly a month ago:

https://lists.yoctoproject.org/pipermail/yocto/2012-December/013041.html

https://lists.yoctoproject.org/pipermail/yocto/2012-December/013057.html

I agree that we shouldn't recommend using the meta-yocto layer.conf as a 
starting point, due to the BBPATH append ordering difference.

And maybe a note about why we order the BBPATH append as we do in 
meta-yocto (see Thomas' concise explanation in the second link above) 
would be appropriate.

Scott

-- 
Scott Garman
Embedded Linux Engineer - Yocto Project
Intel Open Source Technology Center