Re: NFSv4 boot support?

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Antony,

On 05.02.24 10:59, Antony Pavlov wrote:
> On Wed, 31 Jan 2024 22:37:50 +0100
> Ahmad Fatoum <a.fatoum@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].
> 
> I have started integration on picotcp into barebox in 2015, see
>   https://lore.barebox.org/barebox/1436991230-14251-10-git-send-email-antonynpavlov@gmail.com/T/
> 
> At the moment I have WIP barebox-v2023.11 with integrated picotcp 2.1:
> 
>   https://github.com/frantony/barebox/tree/20231127.picotcp

Cool. Looking at Oleksij's repo, it was based on your work. How well does
picotcp work for you? What open issues remain with the patch stack? Is the
barebox integration actively used in projects?

Is https://github.com/tass-belgium/picotcp the official repository? This hasn't
seen development activity in 5 years. lwIP on the other hand still sees active
development.

Regarding the license, inclusion of BSD-licensed code is ok. You can check out
the LICENSES/ subdirectory for the licenses covering barebox.

Cheers,
Ahmad




>>> 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
>>      https://github.com/olerem/barebox/tree/picotcp-2019.06.29
>>      https://github.com/jmaselbas/barebox/commit/4a987bfdc2ad50c13126dd6290d2477c3fc0c87d
>>
>> Cheers,
>> Ahmad
>>
>>>
>>> Dan
>>
>> -- 
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>>
>>
> 
> 

-- 
Pengutronix e.K.                           |                             |
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