[yocto] OpenEmbedded sole base meta layer and poky base meta layers in sync, or not (should be The Same meta base layer, used in different distros)???

[Burton, Ross]

On 23 October 2017 at 10:08, Zoran Stojsavljevic <
zoran.stojsavljevic at gmail.com> wrote:

> > Or better yet use
> > http://www.yoctoproject.org/docs/2.3.2/mega-manual/mega-ma
> nual.html#ref-classes-image-buildinfo
>
> Since I am also (relatively) new to YOCTO, reading these emails makes me
> think about dependencies between YOCTO distros and layers within distros.
>
> Looking what is written here, I decided to do couple of the tests on my
> own to try to understand better how OpenEmbedded (oe-core) base layer and
> Poky distro (with two layers on the top of oe-core) are correlated with
> each other. As my best understanding, poky master tree should do nothing
> more that follow dependencies (with two additional layers) on the
> OpenEmbedded master tree.
>
> OpenEmbedded layer is YOCTO QEMU project on its own. And one can build
> well known QEMU targets on single oe-core.
>
> In order to verify this, i did git clone (at the same time) on two
> distros: oe-core master tree, and on poky master tree.
>
> Now, after building oe-core, I have the following in qemux86-64 target
> /etc/build:
>
> -----------------------
> Build Configuration:  |
> -----------------------
> DISTRO = nodistro
> DISTRO_VERSION = nodistro.0
> -----------------------
> Layer Revisions:      |
> -----------------------
>
> *meta              = master:3b413a80578caacd9a7f405f3c51a3921d78a60d*
>
> At the same time, for poky, I got the following (qemux86-64 target
> /etc/build):
>
> -----------------------
> Build Configuration:  |
> -----------------------
> DISTRO = poky
> DISTRO_VERSION = 2.4
> -----------------------
> Layer Revisions:      |
> -----------------------
> *meta                  = rocko:65d23bd7986615fdfb0f1717b615534a2a14ab80 --
> modified*
> meta-poky         = rocko:65d23bd7986615fdfb0f1717b615534a2a14ab80 --
> modified
> meta-yocto-bsp = rocko:65d23bd7986615fdfb0f1717b615534a2a14ab80 --
> modified
> _______
>
> Now, the question: should meta - rocko and meta - master have (in *BOLD*)
> the SAME master HEAD #???
>

No, they're different repositories so have different SHAs.  However:

$ git show 65d23bd7986615fdfb0f1717b615534a2a14ab80
commit 65d23bd7986615fdfb0f1717b615534a2a14ab80
Author: Randy MacLeod <Randy.MacLeod at windriver.com>
Date:   Mon Oct 16 11:00:44 2017 -0400

    README.qemu: qemuppc64 is not supported

    (From OE-Core rev: 3b413a80578caacd9a7f405f3c51a3921d78a60d)

They're the same commit.

poky is generated using combo-layer, which effectively cherry-picks commits
from the parent repositories (in this case bitbake, oe-core, meta-poky,
meta-yocto-bsp).  This explains why the SHAs don't match, as the history
doesn't match.

Ross
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