New Linux Patch To Allow Booting From Arbitrary Non-Block Device File-Systems
Longtime kernel developer Christoph Hellwig sent out this new patch based on earlier work by Red Hat's Vivek Goyal. Extending the CIFS and NFS root file-system support right now in the kernel, this extension allows for arbitrary non-block device file-systems to be used for the root file-system.
One of the motivations for this patch is for easily allowing VirtIO FS root file-systems with options such as "root=myfs rootfstype=virtiofs rw" but can just as well apply to other file-systems too with this patch of just 40 lines of new code.
See this kernel mailing list thread if such functionality is of interest to you.