initrd is mainly designed to allow system startup to occur in two phases, where the kernel comes up with a minimum set of compiled-in drivers, and where additional modules are loaded from initrd. This document gives a brief overview of the use of initrd.

In Linux systems, initrd (initial ramdisk) is a scheme for loading a temporary root file system into memory, to be used as part of the Linux startup process. initrd and initramfs (from INITial RAM File System) refer to two different methods of achieving this.

2024年3月18日 · initrd gives us the ability to load a RAM disk by the bootloader. The loaded RAM disk is mounted as the root file system, and different programs are run from it. We can also mount a new root file system from a different device, making the bootloader move the former initrd root to a different directory, and we can unmount it.

2024年6月17日 · initrd.img, short for “initial RAM disk,” is an older format that uses a file system image, requiring a loopback device for mounting and typically containing a minimal file system with necessary drivers and executables.

initrd provides the capability to load a RAM disk by the boot loader. This RAM disk can then be mounted as the root file system and programs can be run from it. Afterwards, a new root file system can be mounted from a different device.

See the Linux kernel source file Documentation/admin-guide/initrd.rst (or Documentation/initrd.txt before Linux 4.10) as well as pivot_root(2) and pivot_root(8) for information on the modern method of changing the root filesystem.

2023年12月8日 · initrd stands for "initial RAM disk," a temporary root filesystem used in the boot process. The initrd is loaded by the bootloader along with the kernel image and is essential for the two-stage boot process that modern Linux systems use.