Re: [PATCH v2 11/13] dt-bindings: riscv: Add Supm extension description

[Rob Herring <robh@kernel.org>]

On Fri, Dec 26, 2025 at 03:28:47PM -0600, Alex Elder wrote:
> On 12/22/25 7:04 AM, Guodong Xu wrote:
> > Add description for the Supm extension. Supm indicates support for pointer
> > masking in user mode. Supm is mandatory for RVA23S64.
> > 
> > The Supm extension is ratified in commit d70011dde6c2 ("Update to ratified
> > state") of riscv-j-extension.
> > 
> > Supm depends on either Smnpm or Ssnpm, so add a schema check to enforce
> > this dependency.
> 
> I have the same general question on this, about whether it's really
> necessary for the DT binding to enforce these requirements.  The
> RISC-V specifications are what truly defines their meaning, so I
> don't really see why the DT framework should need to enforce them.
> (That said, I'm sure there are other cases where DT enforces things
> it shouldn't have to.)

Does the specification have some way to check it? What happens if a DT 
is wrong? Are you going to require a DT update to make things right? Or 
the kernel has to work-around the error? Neither is great. So having 
this as a schema makes sense to prevent either scenario.

> 
> And now, having looked at these added binding definitions (in patches
> 07 through 11 in this series), I wonder what exactly is required for
> them to be accepted.  For the most part these seem to just be defining
> how the extensions specified for RISC-V are to be expressed in
> DT files.  It seems to be a fairly straightforward copy from the
> ratified specification(s) to the YAML format.
> 
> Who need to sign off on it?  Conor?  Paul?  DT maintainers?

I generally leave this extension mess to Conor.

Rob