Re: FreeBSD nfsroot - will it work with NFSv4.2?

On Sun, Apr 5, 2026 at 9:16 AM Rick Macklem <[email protected]> wrote:
>
> On Thu, Feb 19, 2026 at 2:23 PM Dan Shelton <[email protected]> wrote:
> >
> > Hello,
> >
> > Will a FreeBSD 15.0 diskless setup with nfsroot work with NFSv4.2?
> I just committed a patch to main that does this, with some limitations.
> It will be in 15.1.
>
> The limitations are:
> - The server must be configured to handle both NFSv3 and NFSv4
>   because the bootstrap code still uses NFSv3.
> - The root directory specified in the "V4:" line in /etc/exports must
>   be "/" so that the root-path is the same for an NFSv3 and NFSv4 mount.
> - The NFSv4 server must be configured to use id-numbers in strings and
>   not be running the nfsused(8) daemon. (This limitation might be lifted
>   in a future commit which hard-wires enough mapping info to make
>   things work until the nfsuserd(8) daemon is running.)
I just did a commit to main that allows the nfsuserd(8) daemon to run
on the NFSv4 root fs.

I'm not 100% sure if it will work for a read/write root fs mount.
(I tested a read-only one, as suggested by Section 34.10 of the
FreeBSD Handbook.

For the nfsuserd(8) daemon setup (ie. name@domain strings for
uid/gid's), you need..

In /boot/loader.conf
boot.nfsroot.user_domain="<user-domain>"
along with the two lines
nfsuserd_enable="YES"
nfsuserd_flags="-domain <user-domain>"
in /etc/sysctl.conf.

rick

>
> The NFSv4 mount is enabled by putting:
> boot.nfsroot.options="nfsv4"
> in the root fs's /boot/loader.conf in the NFS server.
> It also needs:
> vfs.nfs.enable_uidtostring=1
> in /etc/sysctl.conf in the root fs in the NFS server.
>
> I found Mateusz's wiki useful for the rest of the setup:
> https://wiki.freebsd.org/MateuszPiotrowski/BootFreebsdFromNfs
>
> I also did a couple of things...
> - Deleted /etc/hostid in the root fs in the NFS server, so that each
>   client gets a unique kern.hostuuid.
> - Added a line like:
>   tmpfs /tmp tmpfs rw,size=10M,mode=01777 0 0
>   to the /etc/fstab in the root fs in the NFS server, so /tmp was
>   mounted.
>
> Good luck with it, rick
> >
> > Dan
> > --
> > Dan Shelton - Cluster Specialist Win/Lin/Bsd
> >