https://en.wikipedia.org/wiki/Linux_kernel
Linux kernel configuration
Kernel version
Kernel command line parameters
printk
Kernel module APIs
Kernel panic and oops
Pseudo filesystems
Pseudo files
kthread
Timers
IRQ
Kernel utility functions
Linux kernel tracing
Linux kernel hardening
User mode Linux
UIO
Linux kernel interactive stuff
DRM
Linux kernel testing
Linux kernel build system
Virtio
Kernel modules