Re: [PATCH v2 08/13] dt-bindings: riscv: Add descriptions for Za64rs, Ziccamoa, Ziccif, and Zicclsm

[Alex Elder]

On 12/22/25 7:04 AM, Guodong Xu wrote:
> Add descriptions for four extensions: Za64rs, Ziccamoa, Ziccif, and
> Zicclsm. These extensions are ratified in RISC-V Profiles Version 1.0
> (commit b1d806605f87 "Updated to ratified state.").

I think stating the RISC-V profiles commit ID here (in the commit 
header) is good.

I do *not* think it's necessary to include it in the descriptions
for the extensions, below, but I seem to be late to the party in
expressing this opinion...

That commit ID is related to this repository:
  https://github.com/riscv/riscv-profiles.git

I have a few other comments below but generally I think what you
did looks good.  I have one overall question though.

> They are introduced as new extension names for existing features and
> regulate implementation details for RISC-V Profile compliance. According
> to RISC-V Profiles Version 1.0 and RVA23 Profiles Version 1.0, they are
> mandatory for the following profiles:
>
>   - za64rs: Mandatory in RVA22U64, RVA23U64
>   - ziccamoa: Mandatory in RVA20U64, RVA22U64, RVA23U64
>   - ziccif: Mandatory in RVA20U64, RVA22U64, RVA23U64
>   - zicclsm: Mandatory in RVA20U64, RVA22U64, RVA23U64

I did not verify your statements about where these are
optional and mandatory, but I assume they're correct.

> Since Ziccamoa depends on the 'A' extension, add a schema check to
> enforce this dependency.

All of these extensions are related to atomic operations, right?
Don't *all* of them (not just Ziccamoa) depend on the A extension?
Furthermore, the A extension is already mandated by RVA23U64, so
is it really necessary to add this logic?


> Signed-off-by: Guodong Xu <guodong@xxxxxxxxxxxx>
> ---
> v2: New patch.
> ---
>   .../devicetree/bindings/riscv/extensions.yaml      | 34 ++++++++++++++++++++++
>   1 file changed, 34 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
> index 385e1deb23996d294e7662693f1257f910a6e129..a6b9d7e3edf86ecfb117ba72e295ef097bdc9831 100644
> --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
> +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
> @@ -237,6 +237,12 @@ properties:
>               as ratified at commit 4a69197e5617 ("Update to ratified state") of
>               riscv-svvptc.
>   
> +        - const: za64rs
> +          description:
> +            The standard Za64rs extension for reservation set size of at most
> +            64 bytes, as ratified in RISC-V Profiles Version 1.0, with commit
> +            b1d806605f87 ("Updated to ratified state.")

The more complete description says:

    Reservation sets are contiguous, naturally aligned, and a maximum
    of 64 bytes.

But as I read on (below) I suppose using the more succinct description
from the glossary might be best, forcing people who care to go look
at the reference documents.

> +
>           - const: zaamo
>             description: |
>               The standard Zaamo extension for atomic memory operations as
> @@ -378,6 +384,27 @@ properties:
>               in commit 64074bc ("Update version numbers for Zfh/Zfinx") of
>               riscv-isa-manual.
>   
> +        - const: ziccamoa
> +          description:
> +            The standard Ziccamoa extension for main memory (cacheability and
> +            coherence) must support all atomics in A, as ratified in RISC-V
> +            Profiles Version 1.0, with commit b1d806605f87 ("Updated to
> +            ratified state.")

Similar comment here (but also with a similar caveat):

  Main memory regions with both the cacheability and coherence PMAs
  must support all atomics in A.

And I might say "the A extension", but maybe that's a bad idea.

> +
> +        - const: ziccif
> +          description:
> +            The standard Ziccif extension for main memory (cacheability and
> +            coherence) instruction fetch atomicity, as ratified in RISC-V
> +            Profiles Version 1.0, with commit b1d806605f87 ("Updated to
> +            ratified state.")
> +
> +        - const: zicclsm
> +          description:
> +            The standard Zicclsm extension for main memory (cacheability and
> +            coherence) must support misaligned loads and stores, as ratified
> +            in RISC-V Profiles Version 1.0, with commit b1d806605f87 ("Updated
> +            to ratified state.")
> +
>           - const: ziccrse
>             description:
>               The standard Ziccrse extension which provides forward progress
> @@ -795,6 +822,13 @@ properties:
>           then:
>             contains:
>               const: f
> +      # Ziccamoa depends on A

Maybe more than just depends on the A extension.

					-Alex

> +      - if:
> +          contains:
> +            const: ziccamoa
> +        then:
> +          contains:
> +            const: a
>         # Zvfbfmin depends on V or Zve32f
>         - if:
>             contains: