It would be nice if it was possible to do the following with just configuration, and perhaps a path/variable set where to sync up to. When I am trying to configure the Linux kernel, busybox, or u-boot, I am issuing something like this: bitbake -c menuconfig busybox find ./tmp/work -name busybox-A.B.C\* cp ./tmp/work/armv5te-foo-linux-gnueabi/busybox/1.20.2-r7/busybox-1.20.2/.config ../meta-foo/recipes-core/busybox/busybox-1.20.2/defconfig As you can see, this is a bit tiresome, and more importantly: error prone! I have had several occasions now where I forgot the third setup (or even the second) to sync up explicitly which caused us some debugging for hours by the time we realized the real issue is the omitted sync up.
There is a similar (not identical) bug for creating a makecfgfrag (Bug 3862). A similar thing could be created for makedefconfig. However, I don't think we want bitbake tasks to write content to the layer meta-data themselves. It could dump it in tmp/work/..deploy for easier extraction. Alternatively, it could just copy the command to the console to make finding the fragment/.config easier.
That would still be an additional task that I would need to remember to do. In an ideal world, I do not forget it, but it would still be more error-prone than ideal. If it is not done by bitbake, then it is fine to get it done by some other util, but I would like to solve it centrally and automatically.
devtool provides a framework for this kind of workflow and has basic support for saving the kernel config back to the recipe. devtool still needs additional enhancement for working on the kernel though (see bugs 10417, 11188) and I'm not sure it covers the entirety of what's described here either.
Just to summarise this bug is about making it easier to take the final defconfig in WORKDIR and add it back to the metadata.
We should open specific bugs as per Paul in comment 3 for where devtool needs to be improved.