Message-ID: <b3d015aa-01bd-4974-881a-0af297655c55@riscstar.com>
Date: Sun, 28 Dec 2025 17:50:25 -0600
From: Alex Elder <elder@...cstar.com>
To: Guodong Xu <guodong@...cstar.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Paul Walmsley <pjw@...nel.org>,
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Alexandre Ghiti <alex@...ti.fr>, Yixun Lan <dlan@...too.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Thomas Gleixner <tglx@...utronix.de>,
 Samuel Holland <samuel.holland@...ive.com>, Anup Patel
 <anup@...infault.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Jiri Slaby <jirislaby@...nel.org>, Lubomir Rintel <lkundrak@...sk>,
 Yangyu Chen <cyy@...self.name>, Paul Walmsley <paul.walmsley@...ive.com>,
 Conor Dooley <conor@...nel.org>, Heinrich Schuchardt <xypron.glpk@....de>,
 Kevin Meng Zhang <zhangmeng.kevin@...ux.spacemit.com>,
 Andrew Jones <ajones@...tanamicro.com>, devicetree@...r.kernel.org,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
 spacemit@...ts.linux.dev, linux-serial@...r.kernel.org
Subject: Re: [PATCH v2 09/13] dt-bindings: riscv: Add Ssccptr, Sscounterenw,
 Sstvala, Sstvecd, Ssu64xl

On 12/28/25 6:31 AM, Guodong Xu wrote:
> Hi, Alex
> 
> On Sat, Dec 27, 2025 at 5:28 AM Alex Elder <elder@...cstar.com> wrote:
>>
>> On 12/22/25 7:04 AM, Guodong Xu wrote:
>>> Add descriptions for five new extensions: Ssccptr, Sscounterenw, Sstvala,
>>> Sstvecd, and Ssu64xl. These extensions are ratified in RISC-V Profiles
>>> Version 1.0 (commit b1d806605f87 "Updated to ratified state.").
>>>
>>> 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, their
>>> requirement status are:
>>>
>>>    - Ssccptr: Mandatory in RVA20S64, RVA22S64, RVA23S64
>>>    - Sscounterenw: Mandatory in RVA22S64, RVA23S64
>>>    - Sstvala: Mandatory in RVA20S64, RVA22S64, RVA23S64
>>>    - Sstvecd: Mandatory in RVA20S64, RVA22S64, RVA23S64
>>>    - Ssu64xl: Optional in RVA20S64, RVA22S64; Mandatory in RVA23S64
>>
>> Again, I did not verify your statements about where these are
>> optional and mandatory, but I assume they're correct.
> 
> Thanks for the review.
> 
> As mentioned in my response to patch 8, the requirement status for these
> extensions is clearly defined in the RISC-V Profiles specification(s) which
> I mentioned above.
> 
> I have verified these details against the official document to ensure
> accuracy.

Right, my comment here was just to be transparent that *I* did
not check this, and am trusting that what you said is right.
Thanks for confirming.

					-Alex

> The extension descriptions are included in the commit message to provide
> necessary background information.
> 
>>
>>> Signed-off-by: Guodong Xu <guodong@...cstar.com>
>>> ---
>>> v2: New patch.
>>> ---
>>>    .../devicetree/bindings/riscv/extensions.yaml      | 32 ++++++++++++++++++++++
>>>    1 file changed, 32 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
>>> index a6b9d7e3edf86ecfb117ba72e295ef097bdc9831..ed7a88c0ab3b7dc7ad4a4d2fd300d6fb33ef050c 100644
>>> --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
>>> +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
>>> @@ -160,12 +160,26 @@ properties:
>>>                behavioural changes to interrupts as frozen at commit ccbddab
>>>                ("Merge pull request #42 from riscv/jhauser-2023-RC4") of riscv-aia.
>>>
>>> +        - const: ssccptr
>>> +          description: |
>>> +            The standard Ssccptr extension for main memory (cacheability and
>>> +            coherence) hardware page-table reads, as ratified in RISC-V
>>> +            Profiles Version 1.0, with commit b1d806605f87 ("Updated to
>>> +            ratified state.")
>>> +
>>>            - const: sscofpmf
>>>              description: |
>>>                The standard Sscofpmf supervisor-level extension for count overflow
>>>                and mode-based filtering as ratified at commit 01d1df0 ("Add ability
>>>                to manually trigger workflow. (#2)") of riscv-count-overflow.
>>>
>>> +        - const: sscounterenw
>>> +          description: |
>>> +            The standard Sscounterenw extension for support writable enables
>>> +            in scounteren for any supported counter, as ratified in RISC-V
> 
> Here, I used the abbreviated version. See below.
> 
>>> +            Profiles Version 1.0, with commit b1d806605f87 ("Updated to
>>> +            ratified state.")
>>
>> Maybe you should just copy the text from the RVA23 specification
>> for all of these.  So something like:
>>
>>     For any hpmcounter that is not read-only zero, the corresponding
>>     bit in scounteren must be writable.  This was ratified in the
>>     RISC-V Profiles specification version 1.0, with commit ...
>>
> 
> As you noticed, the RVA23 Profile v1.0 provides two versions of explanation
> for Sscounterenw:
> "Sscounterenw: For any hpmcounter that is not read-only zero, the corresponding
> bit in scounteren must be writable"
> "Sscounterenw: Support writeable enables for any supported counter"
> 
> BR,
> Guodong Xu
> 
>>> +
>>>            - const: ssnpm
>>>              description: |
>>>                The standard Ssnpm extension for next-mode pointer masking as
>>> @@ -178,6 +192,24 @@ properties:
>>>                ratified at commit 3f9ed34 ("Add ability to manually trigger
>>>                workflow. (#2)") of riscv-time-compare.
>>>
>>> +        - const: sstvala
>>> +          description: |
>>> +            The standard Sstvala extension for stval provides all needed values
>>> +            as ratified in RISC-V Profiles Version 1.0, with commit b1d806605f87
>>> +            ("Updated to ratified state.")
>>
>> Or alternative to the full text in the spec, you could copy over
>> the abbreviated description listed in the glossary at the end
>> instead.  Something like:
>>
>>     stval provides all needed values.  This was ratified in...
>>
>>                                          -Alex
>>
>>> +
>>> +        - const: sstvecd
>>> +          description: |
>>> +            The standard Sstvecd extension for stvec supports Direct mode as
>>> +            ratified in RISC-V Profiles Version 1.0, with commit b1d806605f87
>>> +            ("Updated to ratified state.")
>>> +
>>> +        - const: ssu64xl
>>> +          description: |
>>> +            The standard Ssu64xl extension for UXLEN=64 must be supported, as
>>> +            ratified in RISC-V Profiles Version 1.0, with commit b1d806605f87
>>> +            ("Updated to ratified state.")
>>> +
>>>            - const: svade
>>>              description: |
>>>                The standard Svade supervisor-level extension for SW-managed PTE A/D
>>>
>>

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