What is the name of the compressed cpio archive used for booting the kernel?

The correct answer is "initramfs." Initramfs stands for "initial RAM filesystem" and is a compressed cpio archive that serves as a temporary root file system for the Linux kernel during the boot process. When the Linux kernel is first loaded into memory, it typically does not yet have access to the root filesystem or drivers needed to fully initialize the system.

Initramfs provides the necessary files and drivers to facilitate this process, allowing the kernel to load essential modules and perform tasks like mounting the actual root filesystem, managing swap, or handling device initialization. It's typically unpacked into RAM and mounted as a virtual filesystem, enabling the kernel to execute the required steps to transition to the real root filesystem.

Understanding initramfs is crucial for system boot management as it improves the boot process, especially in systems with complex drivers or storage configurations. It also allows for a more flexible and dynamic initialization since it can include additional scripts and modules, making it a vital part of the boot process.