[yocto] Where to make image dependent kernel changes while hardware stays same

[Jakob Hasse]

Hello,

we would like to have different images with different kernel 
configs/device trees. E.g., we would like to have systemA with uart2 and 
systemB without uart2 but spi1 instead, with all the different 
configurations and device trees. The hardware does not change in this case.

How can I make such kernel changes depending on the currently used image?

My first trail was  to make different machine configs anyway although 
technically the hardware doesn't change. Then I can append different 
kernel configs in the kernel recipe like this:
SRC_URI_append_systemA = " file://defconfig"
SRC_URI_append_systemB = " file://defconfig"
...with the corresponding defconfigs in their machine specific subdir.

But maybe there is a better way to reflect these kind of changes?

All the Best,
Jakob