config STRICT_DEVMEM bool "Filter access to /dev/mem" depends on MMU help If this option is disabled, you allow userspace (root) access to all of memory, including kernel and userspace memory. Accidental access to this is obviously disastrous, but specific access can be used by people debugging the kernel. If this option is switched on, the /dev/mem file only allows userspace access to memory mapped peripherals. If in doubt, say Y.
config PID_IN_CONTEXTIDR bool "Write the current PID to the CONTEXTIDR register" help Enabling this option causes the kernel to write the current PID to the CONTEXTIDR register, at the expense of some additional instructions during context switch. Say Y here only if you are planning to use hardware trace tools with this kernel.