Re: `io{re,un}map()` build error in s390 under `!CONFIG_HAS_IOMEM`

On Mon, Aug 3, 2026, at 20:09, Miguel Ojeda wrote:
>
> so e.g. an `allnoconfig` with Rust fails.
>
> I assume we will need to `#ifdef` the helpers, plus the users; or stub
> at some layer to avoid changing callers.
>
> I hope that helps & thanks!

I think in practice you'll find that all sensible configurations
will have PCI enabled since that was introduced in the 2012
generation (zEC12), while the oldest supported machines in
the kernel these days are from 2008 (z10) and Red Hat Enterprise
Linux already needs a z14 from 2017.

In theory you should be able to use rust code without PCI MMIO
support, but I can't see any practical downsides to making rust
'depends on HAS_MMIO' to avoid having to add those #ifdef.

Note that we already have 'config COMPILE_TEST depends on HAS_MMIO'
to work around similar problems with random drivers expecting
MMIO support.

      Arnd