When I moved to Canonical and Linaro I stopped using OpenEmbedded. But recently I got some tasks which involved it. In short: there is a plan to use OE to bootstrap ARMv8 support in some Linux distributions.
2 years ago OE guys started creation of OpenEmbedded Core set of metadata. I have to admit that I never used it at that time but supported idea (first mentions of splitting recipes was at OEDEM 2006).
This time using layers is the only way. So I fetched OE Core, OpenEmbedded and Linaro layers and did some builds to find out how it looks today. Some time later Ken Werner left Linaro team so I took over maintenance of meta-linaro layer. Improved documentation a bit and started creating small LAMP like image.
There were issues with toolchain. I use Linaro branded GCC and found out issue with binutils and then with C++ headers — sent some patches and problems were solved by Khem Raj in a bit other way.
After some tests and patches I got LAMP image working out of box. So moved to some more advanced things…
First was update of qemuarmv7a machine to use Versatile Express emulation instead of hacked Versatile PB one. Ken did work for 3.2 kernel but in meantime Yocto moved to 3.4 one. I looked at issues and tried to get it working.
OMG… Now I know why people say that OpenEmbedded have exponentially steep learning curve… Getting kernel into usable state is nightmare. Years ago defconfig was nearly sacred — there were few small changes done to it in kernel.bbclass/linux.inc but it was easy to understand. Now there are KERNEL_FEATURES which may be ignored, big set of scripts, config parts which may be applied (or removed or something else)… I really tried to understand it but my brain decided to go away.
Maybe other day I will manage to understand this magic stuff or will just go for linux-yocto-custom.bb or will write old style linux_3.4.bb recipe without all that magic.