IMHO it would be handy to aid debugging efforts by enabling the dyndbg feature provisioned by kernel .
Though not sure what is entails in regards to cost of storage a/o CPU a/o memory it likely could benefit the development of the distro by being able to generate more in-depth information on user nodes for potential mishaps.
Dynamic debug is designed to allow you to dynamically enable/disable kernel code to obtain additional kernel information.
CONFIG_DYNAMIC_DEBUG kernel config flag is unset.
Sorry for bumping an old thread, but it's currently the top google search result for "openwrt CONFIG_DYNAMIC_DEBUG".
There's an option for this in the openwrt configuration which overrides the kernel configuration, so if you want to enable this you have to turn it on in
> Global build settings
> Kernel build options
> Compile the kernel with dynamic printk
Hopefully this saves someone else some time trying to figure out why you can't just put this option in your kernel config...