Re: [PATCH] nios2: remove the architecture

[Simon Schuster <schuster.simon@siemens-energy.com>]

Hi Ethan, Arnd, Peter and Dinh,

On Mon, May 18, 2026 at 11:29:48AM +0200, Arnd Bergmann wrote:
> We last discussed this a year ago when Simon Schuster mentioned[1]
> that Siemens Energy is still using NIOS-2 in production and would
> prefer to have this still included in Linux for at least another
> few years until the obligation for kernel updates ends.

First off, thank you, Arnd, for remembering us as this patch series came
up and also to Dinh for his maintenance of the architecture!

Regarding our status in relation to nios2, Arnd's response already gives
you the gist:

We are well aware that the architecture was deprecated by Intel and are
therefore phasing it out in favour of more contemporary hardware.
I'm also fully aware of the uncertain future of 32-bit architectures as
a whole [0] and that this fate will come to nios2 sooner or later.
But as of now, the mainline support is still in very good shape.

On Mon, May 18, 2026 at 12:57:35PM +0200, Peter Zijlstra wrote:
> Isn't that what we have LTS branches for?

Unfortunately, as we are an infrastructure provider for civil energy
infrastructure, the refurbishment cycle is a bit slower than for
traditional consumer systems. This implies that the traditional LTS
support duration (max. Dec 2028 as of writing [1]) is rather short, and
we would be glad if we could keep the architecture in mainline for at
least 5 years and only then "decay" to LTS.

On Mon, May 18, 2026 at 11:29:48AM +0200, Arnd Bergmann wrote:
> My feeling is that the maintenance burden of keeping nios2 is
> relatively low. On the other hand, maintaining it out of tree
> as a patch set is also something that should not be all that
> hard if it does get removed.

Judging from the architecture's git history, it seems that it's
currently mainly touched by treewide refactors, which are extremely
helpful as we therefore do not have to piece these changes together 
downstream. In other respects, we try to be good citizens and contribute
bugfixes as well as required cleanups (such as implementing clone3 [2]
and fixing its flag behaviour on 32-bit architectures) as they come up.

If desired, we also would be happy to intensify our support regarding
reviews or testing to share the maintnance burden if it helps to keep
nios2 in mainline a bit longer.

Best regards,
Simon
 
0: https://lwn.net/Articles/1035727/
1: https://www.kernel.org/category/releases.html
2: https://lore.kernel.org/lkml/20250821-nios2-implement-clone3-v1-0-1bb24017376a@siemens-energy.com/