Re: [PATCH v7 1/1] RISC-V: Use SBI SRST extension when available
From: Palmer Dabbelt
Date: Tue Jan 11 2022 - 13:40:44 EST
On Tue, 11 Jan 2022 01:32:24 PST (-0800), aurelien@xxxxxxxxxxx wrote:
On 2021-11-12 17:49, Atish Patra wrote:
On Tue, Nov 9, 2021 at 10:19 AM Heinrich Schuchardt
<heinrich.schuchardt@xxxxxxxxxxxxx> wrote:
>
> On 7/29/21 08:10, Atish Patra wrote:
> > On Wed, Jul 28, 2021 at 9:30 PM Palmer Dabbelt <palmer@xxxxxxxxxxx> 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@xxxxxxxxxxxxxx> wrote:
> >>>>
> >>>> On Wed, Jul 7, 2021 at 1:57 AM Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx> wrote:
> >>>> >
> >>>> > On Mon, 21 Jun 2021 21:46:46 PDT (-0700), anup@xxxxxxxxxxxxxx wrote:
> >>>> > > Hi Palmer,
> >>>> > >
> >>>> > > On Wed, Jun 9, 2021 at 5:43 PM Anup Patel <anup.patel@xxxxxxx> 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?
Not ratified, Frozen (officially as per newly defined RVI process)
> What is the timeline?
>
According to this mail, the "SBI specification is considered as frozen
now as per the RISC-V International policies":
http://lists.infradead.org/pipermail/opensbi/2022-January/002357.html
Therefore can we get this patch queued for 5.17-rc1?
Thanks. Atish had actually pointed this out last night, but I wasn't at
the computer. This in on for-next.