Hi Manoj,
meta-swupdate-boards is just a bunch of examples, without beeing
exhaustive or ready for a product. The example you took just update the
rootfs in a very simple case.
What you have found is correct, and in fact, you have to develop your
own concept for your device. /boot from default build contains DTBs and
kernel, and this is not covered by the example here. You have to
implement your strategy, and store the kernel with a A/B concept, too,
adding separate partitions or moving the kernel into rootfs. Of course,
the same is for DTBs and for whatever should be updated.
Best regards,
Stefano Babic