What are the advantages initrd

[jondkent]

Seen initrd crop up a few times on these forums and I was wondering why you would want/need to use it. I've looked at the documentation in the kernel tree but it not all clear as to why you'd want to use it. Any pointers would help me to decide whether it worth using it or not.

Thanks
Jon

[ebichu]

It allows you to load a RAM disk containing any kernel modules and set-up scripts required before the root partition is mounted. This initial RAM disk is loaded into memory by the thing that loads the kernel (LILO, GRUB, etc.), or rather the compressed version is loaded into memory and the kernel uncompresses it.

It's mostly useful when you don't want to build your own kernel containing the modules required for mounting the root partition, or when the kernel would otherwise be too large to fit on a floppy. (The initrd image could be located on a second floppy.)

It doesn't seem that useful when booting Gentoo off hard disk, as you are expected to build your own kernel anyway, and can build the drivers required for mounting the root partition into the kernel directly, rather than as separate modules.
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