[bug#43219] [PATCH] gnu: Handle nfs-root device strings.

[Stefan]

Hi!

I’d like to propose these minimal changes to support an NFS as a root file 
system.

Currently there are three ways to define the root file system:

 • (file-system (device (label …)) …), 
 • (file-system (device (union …)) …), 
 • (file-system (device "<string>") …).

The manual does not mention that an NFS is currently not supported as a root 
file system. However, NFS mounts are possible already with (file-system (type 
"nfs") (device "<string>") …).

This patch enables users to use an NFS also as a root file system without 
introducing a new syntax.

I was asked before to introduce an <nfs-share> record to achieve the same. And 
I did so, see <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=41820#20>. But due 
to some other PXE efforts – for which I don’t see progress – that patch got on 
hold.

However, that <nfs-share> record would brake with the compatibility of how an 
NFS mount is defined today, and it makes the code much more complex without 
having a real gain.

I think this minimal patch will not conflict with that other PXE effort. Its 
only purpose is to enable the use of an NFS as a root file system already today.


Bye

Stefan