[External] Re: [PATCH v3 1/3] dt-bindings: riscv: clarify Svadu boot-time behavior

[yunhui cui]

Hi Conor,

On Wed, Jun 10, 2026 at 12:09 AM Conor Dooley <conor at kernel.org> wrote:
>
> On Tue, Jun 09, 2026 at 09:00:18PM +0800, Yunhui Cui wrote:
> > Clarify that systems which advertise only Svadu have hardware PTE A/D
> > updating enabled at boot, while systems advertising both Svade and Svadu
> > must enable Svadu explicitly with SBI FWFT.
> >
> > Signed-off-by: Yunhui Cui <cuiyunhui at bytedance.com>
> > Reviewed-by: Qingwei Hu <qingwei.hu at bytedance.com>
> > ---
> >  Documentation/devicetree/bindings/riscv/extensions.yaml | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
> > index 2b0a8a93bb214..b09888e9988de 100644
> > --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
> > +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
> > @@ -294,10 +294,10 @@ properties:
> >                 of the PTE A/D bits or page faults when they need updated.
> >              2) Only Svade present in DT => Supervisor must assume Svade to be
> >                 always enabled.
> > -            3) Only Svadu present in DT => Supervisor must assume Svadu to be
> > -               always enabled.
> > +            3) Only Svadu present in DT => Supervisor must assume Svadu is
> > +               enabled at boot.
>
> Commit message is missing an explanation of why this behaviour change is
> not problematic. Although, to be honest, I am not sure what the changed text
> actually means. If only Svadu is present, then the hardware doesn't support
> Svade, and therefore Svadu would never be anything other than enabled so
> changing the wording to specify "at boot" seems less clear?

The "enabled at boot" wording came from Andrew's feedback on the previous
version: "always" is a sensitive term here because ADUE is writable when
Svadu is implemented, and ADUE=0 behaves as though Svade were implemented.

Would this wording work?

3) Only Svadu present in DT => Supervisor must assume hardware PTE A/D
    updating is enabled by default.

>
> >              4) Both Svade and Svadu present in DT => Supervisor must assume
> > -               Svadu turned-off at boot time. To use Svadu, supervisor must
> > +               Svadu is disabled at boot time. To use Svadu, supervisor must
>
> This change doesn't actually do anything, "turned-off" and "disabled"
> are the same thing - although the latter is more desirable wording I
> think. I have no problems with this portion of the patch.
>
> >                 explicitly enable it using the SBI FWFT extension.
> >
> >          - const: svadu
> > --
> > 2.39.5
> >

Thanks,
Yunhui