Thanks, that helped a lot. I was able to track this down to a combination of statd (which I already suspected) and idmapd (which I should have remembered from recent changes to the upstart jobs, but had forgotten about).
Changing statd to start on virtual-filesystems, and changing idmapd to not block the / mountpoint, gets us clear of the boot hang.
This is not a perfect fix because it means that anyone trying to do nfsroot over nfsv4 is out of luck; but it's strictly an improvement over the status quo, and it's been suggested that nfsroot doesn't actually work on nfsv4, so I'll go ahead with it for now.
Thanks, that helped a lot. I was able to track this down to a combination of statd (which I already suspected) and idmapd (which I should have remembered from recent changes to the upstart jobs, but had forgotten about).
Changing statd to start on virtual- filesystems, and changing idmapd to not block the / mountpoint, gets us clear of the boot hang.
This is not a perfect fix because it means that anyone trying to do nfsroot over nfsv4 is out of luck; but it's strictly an improvement over the status quo, and it's been suggested that nfsroot doesn't actually work on nfsv4, so I'll go ahead with it for now.