NFSv4 boot support?

[Dan Shelton]

On Mon, 5 Feb 2024 at 19:31, Antony Pavlov <antonynpavlov at gmail.com> wrote:
>
> On Wed, 31 Jan 2024 22:37:50 +0100
> Ahmad Fatoum <a.fatoum at pengutronix.de> wrote:
>
> Hi all!
>
> > Hello Dan,
> >
> > On 31.01.24 22:03, Dan Shelton wrote:
> > > Hello!
> > >
> > > Does barebox support booting from a NFSv4 filesystem, e.g. boot from
> > > NFSv4 filesystem into a Linux NFSv4 netroot (diskless machine)?
> >
> > The barebox network stack only does UDP/IP. There have been attempts to
> > bring a TCP stack into barebox, but none have so far succeeded to
> > make it mainline. This is a hard requirement before we can consider
> > supporting NFSv4. I hope that lwIP could fill this gap in the future,
> > but no one is actively continuing this work as far as I am aware[1].
> >
> > > We need NFSv4, because it does not need rpcbind, and combines
> > > filesystem, lockd and other stuff all in one TCP port (2049). Site
> > > policy also does not allow NFSv2/NFSv3, but allows NFSv4.
> >
> > Please note that this only concerns barebox and that kernel nfsroot is
> > unaffected. You can load kernel and device tree over TFTP and supply a
> > suitable command line argument to the kernel to use a NFS root.
> >
> > The standard net boot target does just that:
> > https://elixir.bootlin.com/barebox/v2024.01.0/source/defaultenv/defaultenv-2-base/boot/net
> >
> > It specifies TCP, but hardcodes v3 currently. I guess we could drop the v3 and let
> > the kernel decide on its own what version it will use? If that doesn't work, you can
> > override the file locally in your environment, e.g. via CONFIG_DEFAULT_ENVIRONMENT
> > pointing at a directory that contains a boot/net file with the appropriate
> > changes (or just call your boot target something else like boot/nfsv4).
> >
> > Hope this helps.
> >
> > [1]: Some attempts I am aware of:
> >      https://github.com/a3f/barebox/tree/lwip
>
> It looks like lwip is BSD-3-clause-licensed. Can we use the BSD-3-clause code in barebox?

I think yes

Dan
-- 
Dan Shelton - Cluster Specialist Win/Lin/Bsd