Re: [PATCH] gpio: sim: added configfs option for static base

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Fri, Feb 28, 2025 at 2:54 PM Sebastian Dietz <s.dietz@xxxxxxxxxxxxxxx> wrote:
>
> On 28.02.25 14:22, Bartosz Golaszewski wrote:
> > On Fri, Feb 28, 2025 at 1:46 PM Sebastian Dietz <s.dietz@xxxxxxxxxxxxxxx> wrote:
> >>
> >> To replicate gpio mappings of systems it is sometimes needed to have
> >> the base at static values.
> >>
> >
> > Can you give me more info on why you'd need that? Static base is
> > largely a legacy and deprecated feature, there's ongoing effort to
> > remove it from the kernel.
> >
> >> base is treated as unsigned as there doesn't happen to be a
> >> fwnode_property_read_s32().
> >>
> >
> > Ha! That's interesting, I wonder why that is. We do have signed
> > variants for OF-specific properties.
> >
> > Bart
>
> We are building digital twins for embedded devices for security research. The
> firmware of these devices often export static gpio pins which we simulate
> using gpio-sim. With this patch we are able to satisfy these conditions.
>
> While the feature may be deprecated, i would argue that it makes sense and
> fits the nature of a simulator to be able to configure it manually.
>
> BR,
> Sebastian

What kind of digital twins? Using qemu? In any case - I really dislike
the idea of extending the configfs interface of gpio-sim with an
attribute to support an option that we're actively trying to remove
from GPIO core. Unless you can give me a really convincing argument, I
will allow myself to use my maintainers' right to NAK this one.

Bart