[PATCH v7 1/1] RISC-V: Use SBI SRST extension when available

Tue Nov 9 07:19:22 PST 2021

On 7/29/21 08:10, Atish Patra wrote:
> On Wed, Jul 28, 2021 at 9:30 PM Palmer Dabbelt <palmer at dabbelt.com> wrote:
>>
>> On Sun, 11 Jul 2021 11:59:33 PDT (-0700), Palmer Dabbelt wrote:
>>> On Fri, 09 Jul 2021 22:01:02 PDT (-0700), Anup Patel wrote:
>>>>
>>>>
>>>> On 08/07/21, 9:22 AM, "Anup Patel" <anup at brainfault.org> wrote:
>>>>
>>>>      On Wed, Jul 7, 2021 at 1:57 AM Palmer Dabbelt <palmerdabbelt at google.com> wrote:
>>>>      >
>>>>      > On Mon, 21 Jun 2021 21:46:46 PDT (-0700), anup at brainfault.org wrote:
>>>>      > > Hi Palmer,
>>>>      > >
>>>>      > > On Wed, Jun 9, 2021 at 5:43 PM Anup Patel <anup.patel at wdc.com> wrote:
>>>>      > >>
>>>>      > >> The SBI SRST extension provides a standard way to poweroff and
>>>>      > >> reboot the system irrespective to whether Linux RISC-V S-mode
>>>>      > >> is running natively (HS-mode) or inside Guest/VM (VS-mode).
>>>>      > >>
>>>>      > >> The SBI SRST extension is available in the SBI v0.3 specification.
>>>>      > >> (Refer, https://github.com/riscv/riscv-sbi-doc/releases/tag/v0.3.0-rc1)
>>>>      > >
>>>>      > > Can you please consider this patch for Linux-5.14-rc1 ?
>>>>      > >
>>>>      > > The SBI v0.3 spec is already frozen and this patch has been
>>>>      > > floating on LKML for quite a few months now.
>>>>      >
>>>>      > I didn't realize that SBI-0.3 had been frozed.  That link is to a RC,
>>>>      > the cooresponding v0.3.0 tag isn't in that repo.  Can you give me a
>>>>      > pointer to the frozen spec?
>>>>
>>>>      Here's the link to SBI v0.3.0 tag:
>>>>      https://github.com/riscv/riscv-sbi-doc/releases/tag/v0.3.0
>>>>
>>>>      We treat RC tags as frozen in SBI spec because no functional
>>>>      changes are done in SBI spec after it is tagged as RC. We only
>>>>      do typo fixes and clarifications on SBI spec RC release.
>>>
>>> Treating the 0.3.0-rc1 as frozen as soon as it's released is a
>>> terrifying policy: some of the fixes I sent in after I saw rc1 released
>>> change the actual meaning of the text, even if they were meant to change
>>> them to what I thought the intended meaning was supposed to be.  That
>>> means the actual text of 0.3.0-rc1 and 0.3.0 conflict with each other.
>>> Given that frozen comes with a guarntee of backwards compatibility, does
>>> that mean that the behavior allowed by 0.3.0-rc1 is compliant with the
>>> SBI, even if it was likely just allowed by a wording mistake?
>>>
>>> If you're going to freeze things at rc1 then you really need to be quite
>>> explicit about that, as generally the point of RCs is to elicit
>>> review/testing.  Looks like I was the only person to have provided any
>>> review, so I guess I was the only one who assumed "We don't expect any
>>> significant functional changes. We will wait for any further feedback
>>> and release the official v0.3 in a month or so." actually meant "this is
>>> frozen".
>>>
>>>> Can you take this patch for Linux-5.14 ??
>>>
>>> No, sorry, it's way too late for that.  Please be specific about when
>>> you freeze specifications in the future, so we can all stay on the same
>>> page.
>>
>> I went and talked to Krste, and he says that there's a whole process for
>> freezing extensions that this hasn't gone through.  They don't have
>> anything written down that I can point to, but can you guys please just
>> get on the same page about this?  It seems like every time I talk to
> 
> Absolutely. The freezing extensions process is documented right now[1]
> but that is only meant
> for ISA/hardware/platform specifications. There is no process defined
> for a SBI specification which is purely
> a software specification because SBI specification release
> processes(v0.1 and v0.2) predate these documented processes.
> The SBI specification is owned by the Platform HSC which falls under
> the purview of software HC.
> You can see a detailed chart of the RVI organization at [2]. All the
> aspects of SBI specification are discussed
> in platform meetings[3] and frozen only after public review[4] and
> approval from the platform working group
> and the software HC. The official SBI specification(v0.3) will also be
> available along with all other RISC-V specifications
> once they figure out how to structure non-ISA specifications.
> 
> I have cc'd Kumar (chair of the Platform HSC) and Philip (chair of the
> software HC) in case they want to add anything.
> I was not aware of the fact that Krste/Andrew are not aware of the
> progress of the SBI specification.
> I will raise this topic during the next meeting and make sure they are
> in the loop as well.
> 
>> someone from the RISC-V foundation I get a conflicting description of
>> what's going on, and I'm entirely out of patience when it comes to
>> getting blamed for all the chaos over there.
>>
> I agree the RVI process has not been very clear in the past. However,
> that has changed a lot in recent times thanks to Mark and
> other working group chairs. I don't think anybody is blaming you for
> the delay in ratification of the RVI specifications.
> There is a clear path for all the specifications to be ratified e.g.
> the AIA and H extensions are planned to be frozen by the end of this
> year.
> Let me know if you want to see the timeline of each specification and
> I can point you to the correct sheet.
> 
> [1] https://docs.google.com/presentation/d/1nQ5uFb39KA6gvUi5SReWfIQSiRN7hp6z7ZPfctE4mKk/edit#slide=id.ga0a994c3c8_0_6
> [2] https://docs.google.com/presentation/d/1eEVuu6lRZd9iiDnZQSZME7Q7svtTG3pGIKHPmZ79B8E/edit#slide=id.ga275a504df_0_9
> [3] https://github.com/riscv/riscv-platform-specs/wiki
> [4] https://lists.riscv.org/g/tech-unixplatformspec/message/1042

https://github.com/riscv-non-isa/riscv-sbi-doc/releases/tag/v0.3.1-rc1
has:

"This tag the release candidate of version 0.3.1 of the RISC-V SBI 
specification. It doesn't have any significant changes other than typos.
A new release is created to adapt the ratification process for non-ISA 
specifications defined by RVI recently."

Has this patch to wait until release 0.3.1 of the SBI specification is 
ratified?
What is the timeline?

Could you, please, provide a link the the non-ISA ratification process 
description.

Best regards

Heinrich