fastboot – How to get information parameters from kernel after boot loads android?

when an (Android) bootloader starts loading kernel, it passes some parameters to the kernel (for example androidboot.verifiedbootstate, …),how to get the information whether boot gets successful or failed and it should notifies to the user application?

I have gone through this article how it will communicate Verified Boot state to users? it means user application? Is there any sample application to communicate from verified boot state to user as toast message?