[OE-core] [RFC] Layer rework proposal

[Koen Kooi]

Hi,

This has come up in the past, but no one has had time to site down and write a proposal yet.

Problem description: The OE-core layer has both too much in it and not enough.

Currently OE-core is basically a relabeling of the poky fork of OE. Due to that heritage is has bits in it that aren't considered 'core', but serve as a testbed for the proper core metadata. The prime example of this is the sato suite. To address this we will need to come up with guidelines what goes into OE-core and what people expect to get out of it. Here's a start:

Highlevel goals:

	1) Have a high quality set of "core" metadata
	2) OE-core needs to be useful on its own
	3) OE-core needs to be testable on its own

Concrete rootfs goals:

	a) be able to build for the 4 blessed architectures: arm, mips, powerpc, x86
	b) have multilib support
	c) be able to build a rootfs that has:
		o package management (rpm/deb/opkg)
		o networking support (ifupdown/connman/dnsmasq)
		o have remote access (dropbear/openssh)
		o have user management (shadow/pam)

I think it's safe to say that we all agree on that minimum set of goals.  The tricky thing is where to put multimedia and GUI stuff. Qt and GTK are important enough to get put in core, but where do we draw the line? Where do we stop splitting things in recipes-* and start splitting them into layers and should those layers live in seperate repositories?

My list of non-BSP, non-distro layers is:

BBLAYERS = " \
  ${TOPDIR}/sources/meta-openembedded/meta-oe \
  ${TOPDIR}/sources/meta-openembedded/meta-efl \
  ${TOPDIR}/sources/meta-openembedded/meta-gpe \
  ${TOPDIR}/sources/meta-openembedded/meta-gnome \
  ${TOPDIR}/sources/meta-openembedded/meta-xfce \
  ${TOPDIR}/sources/openembedded-core/meta \
  "

The gpe, gnome and xfce layers need things like glib-2.0 and gtk, but there's a larger overlay between the 3, so gpe and xfce end up depending on the gnome layer. Meta-oe is the place where people put things they don't want to maintain in a seperate layer, which isn't going to scale longterm.

My not-so-fully-formed idea is:

core - implements above goals
x11 - base xorg libs, headers, apps. Has bbappends for core recipes to add x11 support via DISTRO_FEATURES
gtk - base gtk things, libs, themes, icons, modules
qt - base qt things + qwt

efl - depends on core,x11
gnome - depends on core,x11,gtk
gpe - depends on core,x11,gtk
opie - depends on core,qt
sato - depends on core,x11,gtk
xfce - depends on core,x11,gtk, gnome

and finally:

oe - leftovers

With this layer structure as starting point can we start a discussion on how people would like to set it split? I'd like to leave the question of which layer goes into what repository for later.

regards,

Koen