add boot argument to allow legacy change_root removal

[Jeremy Jackson]

Binary package hint: initramfs-tools

In Linux 2.6 the change_root method of invoking initrd is considered "legacy", and might be removed in future. The new method is pivot_root, which does not have any special case code paths in kernel for initrd after it's block device /dev/ram0 is created. The kernel should be booted "vmlinux root=/dev/ram0" which will mount the initrd, and execute /sbin/init.

At present, this is problematic for initrd-tools (Gutsy), since there is no way to specify the "real" root filesystem that is desired, without using root= kernel commandline argument.

I propose a new argument be interpreted by initrd-tools /init script, to allow migration to a fixed "root=/dev/ram0" on all kernels using initrd to mount the real root device. There is precedent with rdinit=, although "rdroot=/dev/sda1" seems counterintuitive. Alternatives should be considered that are not confusing. Perhaps root2=, realroot=, or some other form.

Parsing the new argument could be conditional on finding "root=/dev/ram0" in kernel commandline, to make things more precise.

[maximilian attems (maks-debian)]

initrd-tools is long gone, thus closing.