A RAM disk is a block device backed by memory. They can not be created at runtime at the moment, but are set up during build to store the root file_system in it. This way no mass storage device driver is required to boot.
Linux boots with a ram disk (initrd) to load additional drivers, not for the full root file system.
Converts the filesystem.img into an array and embeds it into the kernel binary.
See RAMDISK_EMBEDDED in MakefileCommon.mk.
Boot loaders and qemu can load a file into RAM and provide the location to the kernel via the device tree file.
Overview: kernel
Subsystems: interrupts | devices | file_system | memory_management processes | scheduling | syscalls
Devices: ramdisk