[PATCH 1/3] dt-bindings: riscv: Add Supm extension description

[Guodong Xu]

On Fri, Jan 23, 2026 at 2:52 AM Conor Dooley <conor at kernel.org> wrote:
>
> On Fri, Jan 16, 2026 at 10:10:31AM +0800, 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.
> >
> > Signed-off-by: Guodong Xu <guodong at riscstar.com>
> > ---
> >  Documentation/devicetree/bindings/riscv/extensions.yaml | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
> > index 4ffd61926505..1922dff03787 100644
> > --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
> > +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
> > @@ -262,6 +262,23 @@ properties:
> >              ratified in RISC-V Profiles Version 1.0, with commit b1d806605f87
> >              ("Updated to ratified state.")
> >
> > +        - const: supm
> > +          description: |
> > +            The standard Supm extension for pointer masking support in user
> > +            mode (U-mode) as ratified at commit d70011dde6c2 ("Update to
> > +            ratified state") of riscv-j-extension.
> > +
> > +            Supm represents a combination of underlying hardware capability
> > +            (Smnpm or Ssnpm), U-mode consumer privilege level, and M/S-mode
>
> Should we therefore make this require that Smnpm or Ssnpm are present?

I'm not sure. Would U-mode DTBs typically omit the privileged extensions like
Smnpm/Ssnpm, making such a dependency impractical?

-Guodong

>
> > +            software configuration that enables pointer masking for U-mode.
> > +
> > +            DO NOT include this property in device trees targeting privileged
> > +            system software (S-mode or M-mode).
> > +
> > +            This property is only appropriate in device trees provided to
> > +            U-mode software where the next-higher-privilege-mode supports
> > +            Smnpm or Ssnpm and enables it for U-mode.
> > +
> >          - const: svade
> >            description: |
> >              The standard Svade supervisor-level extension for SW-managed PTE A/D
> >
> > --
> > 2.43.0
> >