I've followed this tutorial when it comes to compiling a kernel for the Raspberry Pi. I'm installing onto a properly partitioned SD card, which I completely formatted first (it now has a fat32 boot partition and ext4 file system partition). However, I believe that, in the linked tutorial, they are installing their compiled kernel onto an SD card that already contained an image of Rasbpian. This is because when I boot my Pi with my SD card (the only directory in the file system in my SD is the lib/ directory containing firmware/ and modules/), the boot fails, saying:
PANIC: No init found
I figure that this is because there is because of a lack of a file system present on the SD card during the boot (or something of the like, I'm very new to this entire process). I've done some Googling and come across the concept of an initramfs--is my problem that I need one configured to allow the the boot process to continue? Should I be generating an initramfs, or is it best to just load my custom kernels onto SD cards that have already been imaged with the kernel I am customizing from?