If that is the intention, the text should be changed to "Returns 0 if the given SBI extension ID (EID) is not available, or an implementation defined non-zero value if it is available". Although, if the extensions aren't defining any meaning to the various possible non-zero values, I personally don't see why we shouldn't change it to "returns one if it is available".

Jonathan

On Wed, Jan 12, 2022 at 3:32 PM Atish Kumar Patra <atishp@...> wrote:

On Wed, Jan 12, 2022 at 10:59 AM Jonathan Behrens <behrensj@...> wrote:
>
> If I understand correctly, per the description of `sbi_probe_extension`, each of the extensions are supposed to specify an "extension-specific non-zero value" to return if they are available. However, right now I don't think any of them do. Is this something that should be fixed?
>

The description says "Returns 0 if the given SBI extension ID (EID) is
not available, or an extension-specific non-zero value if it is
available"
The specification says it should be non-zero as the value "0"
indicates non-availability of the extension. The exact return value
should be an implementation detail.

> Jonathan
>
> On Wed, Jan 12, 2022 at 1:44 PM atishp via lists.riscv.org <atishp=rivosinc.com@...> wrote:
>>
>> I just realized that the below email was not delivered to unix
>> platform mailing list and
>> linux-riscv mailing list because of the attachment. Reseeding it again
>> without the
>> attachment. Apologies for the noise.
>>
>> -----------------------------------------------------------------------------------------------
>> We are delighted to announce the start of the public review period for
>> the Non-ISA Supervisor Binary Interface (SBI) specification. The
>> SBI specification is considered as frozen now as per the RISC-V International
>> policies.
>>
>> The review period begins today, Monday Jan 10, and ends on Monday
>> Jan 24 (inclusive).
>>
>> The specification can be found here
>> https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v1.0-rc1/riscv-sbi.pdf
>>
>> which was generated from the source available in the following GitHub
>> repository:
>> https://github.com/riscv-non-isa/riscv-sbi-doc
>>
>> To respond to the public review, please either reply to this email or
>> send comments to the platform mailing list[1] or add issues to the
>> SBI GitHub repo[2]. We welcome all input and appreciate your time and
>> effort in helping us by reviewing the specification.
>>
>> During the public review period, corrections, comments, and
>> suggestions, will be gathered for review by the Platform HSC members. Any
>> minor corrections and/or uncontroversial changes will be incorporated
>> into the specification. Any remaining issues or proposed changes will
>> be addressed in the public review summary report. If there are no
>> issues that require incompatible changes to the public review
>> specification, the platform HSC will recommend the updated
>> specifications be approved and ratified by the RISC-V Technical
>> Steering Committee and the RISC-V Board of Directors.
>>
>> SBI specification is non-ISA specifications and will evolve over time
>> with new extensions as long as they are backward compatible. Any such
>> proposals for new extensions can be included in the future releases
>> after proper discussions in the platform working group meetings.
>>
>> Thanks to all the contributors for all their hard work.
>>
>> [1] tech-unixplatformspec@...
>> [2] https://github.com/riscv-non-isa/riscv-sbi-doc/issues
>>
>> Regards,
>> Atish Patra
>>
>>
>>
>>
>>

HI Andrew,

On Wed, Jan 19, 2022 at 6:31 AM Andrew Waterman <andrew@...> wrote:
>
> Hi Atish,
>
> I've got some minor feedback from the Architecture Review committee:
>
> We think that only the RV64 SBI should be ratified at this time.  The RV32 variants are likely to need some reworking (e.g., passing a physical address as an unsigned long precludes use of the full 34-bit physical-address space), and the RV32 variants aren't currently in high demand, anyway.

The RV32 physical address space limitation only impacts SBI RFENCE
calls and SBI HSM calls. A RV32 system can still use these calls as
long as their physical address space is within 4GB.

I suggest we document this RV32 limitation in SBI RFENCE and SBI HSM
chapters for SBI v1.0 and plan to address this in SBI v2.0.

>
> It would be helpful to add some non-normative text about what the SBI assumes about discovery.  For example, there's no SBI call to retrieve the value of the misa CSR--which is reasonable because the OS is presumably expected to retrieve this information from the DeviceTree--but readers who don't know that might find this surprising.

I agree with this suggestion. We got this question multiple times in
the past as well.

Regards,
Anup

>
> Thanks,
> Andrew
>
> On Wed, Jan 12, 2022 at 10:43 AM <atishp@...> wrote:
>>
>> I just realized that the below email was not delivered to unix
>> platform mailing list and
>> linux-riscv mailing list because of the attachment. Reseeding it again
>> without the
>> attachment. Apologies for the noise.
>>
>> -----------------------------------------------------------------------------------------------
>> We are delighted to announce the start of the public review period for
>> the Non-ISA Supervisor Binary Interface (SBI) specification. The
>> SBI specification is considered as frozen now as per the RISC-V International
>> policies.
>>
>> The review period begins today, Monday Jan 10, and ends on Monday
>> Jan 24 (inclusive).
>>
>> The specification can be found here
>> https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v1.0-rc1/riscv-sbi.pdf
>>
>> which was generated from the source available in the following GitHub
>> repository:
>> https://github.com/riscv-non-isa/riscv-sbi-doc
>>
>> To respond to the public review, please either reply to this email or
>> send comments to the platform mailing list[1] or add issues to the
>> SBI GitHub repo[2]. We welcome all input and appreciate your time and
>> effort in helping us by reviewing the specification.
>>
>> During the public review period, corrections, comments, and
>> suggestions, will be gathered for review by the Platform HSC members. Any
>> minor corrections and/or uncontroversial changes will be incorporated
>> into the specification. Any remaining issues or proposed changes will
>> be addressed in the public review summary report. If there are no
>> issues that require incompatible changes to the public review
>> specification, the platform HSC will recommend the updated
>> specifications be approved and ratified by the RISC-V Technical
>> Steering Committee and the RISC-V Board of Directors.
>>
>> SBI specification is non-ISA specifications and will evolve over time
>> with new extensions as long as they are backward compatible. Any such
>> proposals for new extensions can be included in the future releases
>> after proper discussions in the platform working group meetings.
>>
>> Thanks to all the contributors for all their hard work.
>>
>> [1] tech-unixplatformspec@...
>> [2] https://github.com/riscv-non-isa/riscv-sbi-doc/issues
>>
>> Regards,
>> Atish Patra
>>
>>
>>
>>
>>

Hi Andrew,

On Wed, Jan 19, 2022 at 11:38 AM Andrew Waterman <andrew@...> wrote:
>
>
>
> On Tue, Jan 18, 2022 at 7:48 PM Anup Patel <apatel@...> wrote:
>>
>> HI Andrew,
>>
>> On Wed, Jan 19, 2022 at 6:31 AM Andrew Waterman <andrew@...> wrote:
>> >
>> > Hi Atish,
>> >
>> > I've got some minor feedback from the Architecture Review committee:
>> >
>> > We think that only the RV64 SBI should be ratified at this time.  The RV32 variants are likely to need some reworking (e.g., passing a physical address as an unsigned long precludes use of the full 34-bit physical-address space), and the RV32 variants aren't currently in high demand, anyway.
>>
>> The RV32 physical address space limitation only impacts SBI RFENCE
>> calls and SBI HSM calls. A RV32 system can still use these calls as
>> long as their physical address space is within 4GB.
>>
>> I suggest we document this RV32 limitation in SBI RFENCE and SBI HSM
>> chapters for SBI v1.0 and plan to address this in SBI v2.0.
>
>
> It's true that specific example is limited to those calls, but I'll re-emphase the "e.g."  The RV32 variants have not gotten much road testing because there isn't much demand for them--which again calls into question why we are rushing to ratify them.  So, I'll re-emphasize our suggestion that we only ratify the RV64 versions.

I mostly agree with your suggestion considering the fact that we have
very few (or none) RV32 Linux (or RichOS) capable systems.

I would also like to correct my previous comment about the RV32
limitation. The RV32 limitation only affects SBI HSM and does not
affect any other SBI extension (including SBI RFENCE) because SBI
RFENCE calls take virtual address as "unsigned long" parameter. In
other words, on a RV32 system the SBI HSM start and suspend calls will
need a physical address within the 4GB address range.

Regards,
Anup

>
>>
>> >
>> > It would be helpful to add some non-normative text about what the SBI assumes about discovery.  For example, there's no SBI call to retrieve the value of the misa CSR--which is reasonable because the OS is presumably expected to retrieve this information from the DeviceTree--but readers who don't know that might find this surprising.
>>
>> I agree with this suggestion. We got this question multiple times in
>> the past as well.
>
>
> Cool, thanks!
>
>>
>>
>> Regards,
>> Anup
>>
>> >
>> > Thanks,
>> > Andrew
>> >
>> > On Wed, Jan 12, 2022 at 10:43 AM <atishp@...> wrote:
>> >>
>> >> I just realized that the below email was not delivered to unix
>> >> platform mailing list and
>> >> linux-riscv mailing list because of the attachment. Reseeding it again
>> >> without the
>> >> attachment. Apologies for the noise.
>> >>
>> >> -----------------------------------------------------------------------------------------------
>> >> We are delighted to announce the start of the public review period for
>> >> the Non-ISA Supervisor Binary Interface (SBI) specification. The
>> >> SBI specification is considered as frozen now as per the RISC-V International
>> >> policies.
>> >>
>> >> The review period begins today, Monday Jan 10, and ends on Monday
>> >> Jan 24 (inclusive).
>> >>
>> >> The specification can be found here
>> >> https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v1.0-rc1/riscv-sbi.pdf
>> >>
>> >> which was generated from the source available in the following GitHub
>> >> repository:
>> >> https://github.com/riscv-non-isa/riscv-sbi-doc
>> >>
>> >> To respond to the public review, please either reply to this email or
>> >> send comments to the platform mailing list[1] or add issues to the
>> >> SBI GitHub repo[2]. We welcome all input and appreciate your time and
>> >> effort in helping us by reviewing the specification.
>> >>
>> >> During the public review period, corrections, comments, and
>> >> suggestions, will be gathered for review by the Platform HSC members. Any
>> >> minor corrections and/or uncontroversial changes will be incorporated
>> >> into the specification. Any remaining issues or proposed changes will
>> >> be addressed in the public review summary report. If there are no
>> >> issues that require incompatible changes to the public review
>> >> specification, the platform HSC will recommend the updated
>> >> specifications be approved and ratified by the RISC-V Technical
>> >> Steering Committee and the RISC-V Board of Directors.
>> >>
>> >> SBI specification is non-ISA specifications and will evolve over time
>> >> with new extensions as long as they are backward compatible. Any such
>> >> proposals for new extensions can be included in the future releases
>> >> after proper discussions in the platform working group meetings.
>> >>
>> >> Thanks to all the contributors for all their hard work.
>> >>
>> >> [1] tech-unixplatformspec@...
>> >> [2] https://github.com/riscv-non-isa/riscv-sbi-doc/issues
>> >>
>> >> Regards,
>> >> Atish Patra
>> >>
>> >>
>> >>
>> >>
>> >>

On Wed, Jan 12, 2022 at 12:50 PM Jonathan Behrens <behrensj@...> wrote:

If that is the intention, the text should be changed to "Returns 0 if the given SBI extension ID (EID) is not available, or an implementation defined non-zero value if it is available". Although, if the extensions aren't defining any meaning to the various possible non-zero values, I personally don't see why we shouldn't change it to "returns one if it is available".

I think allowing implementation-defined nonzero rather than requiring it be 1 is OK, but I agree with your proposed wording change.

Jonathan

On Wed, Jan 12, 2022 at 3:32 PM Atish Kumar Patra <atishp@...> wrote:

On Wed, Jan 12, 2022 at 10:59 AM Jonathan Behrens <behrensj@...> wrote:
>
> If I understand correctly, per the description of `sbi_probe_extension`, each of the extensions are supposed to specify an "extension-specific non-zero value" to return if they are available. However, right now I don't think any of them do. Is this something that should be fixed?
>

The description says "Returns 0 if the given SBI extension ID (EID) is
not available, or an extension-specific non-zero value if it is
available"
The specification says it should be non-zero as the value "0"
indicates non-availability of the extension. The exact return value
should be an implementation detail.

> Jonathan
>
> On Wed, Jan 12, 2022 at 1:44 PM atishp via lists.riscv.org <atishp=rivosinc.com@...> wrote:
>>
>> I just realized that the below email was not delivered to unix
>> platform mailing list and
>> linux-riscv mailing list because of the attachment. Reseeding it again
>> without the
>> attachment. Apologies for the noise.
>>
>> -----------------------------------------------------------------------------------------------
>> We are delighted to announce the start of the public review period for
>> the Non-ISA Supervisor Binary Interface (SBI) specification. The
>> SBI specification is considered as frozen now as per the RISC-V International
>> policies.
>>
>> The review period begins today, Monday Jan 10, and ends on Monday
>> Jan 24 (inclusive).
>>
>> The specification can be found here
>> https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v1.0-rc1/riscv-sbi.pdf
>>
>> which was generated from the source available in the following GitHub
>> repository:
>> https://github.com/riscv-non-isa/riscv-sbi-doc
>>
>> To respond to the public review, please either reply to this email or
>> send comments to the platform mailing list[1] or add issues to the
>> SBI GitHub repo[2]. We welcome all input and appreciate your time and
>> effort in helping us by reviewing the specification.
>>
>> During the public review period, corrections, comments, and
>> suggestions, will be gathered for review by the Platform HSC members. Any
>> minor corrections and/or uncontroversial changes will be incorporated
>> into the specification. Any remaining issues or proposed changes will
>> be addressed in the public review summary report. If there are no
>> issues that require incompatible changes to the public review
>> specification, the platform HSC will recommend the updated
>> specifications be approved and ratified by the RISC-V Technical
>> Steering Committee and the RISC-V Board of Directors.
>>
>> SBI specification is non-ISA specifications and will evolve over time
>> with new extensions as long as they are backward compatible. Any such
>> proposals for new extensions can be included in the future releases
>> after proper discussions in the platform working group meetings.
>>
>> Thanks to all the contributors for all their hard work.
>>
>> [1] tech-unixplatformspec@...
>> [2] https://github.com/riscv-non-isa/riscv-sbi-doc/issues
>>
>> Regards,
>> Atish Patra
>>
>>
>>
>>
>>

On 1/27/22 09:33, atishp@... wrote:
>
>
> On Tue, Jan 18, 2022 at 2:46 PM Andrew Waterman <andrew@...
> <mailto:andrew@...>> wrote:
>
>
>
>     On Wed, Jan 12, 2022 at 12:50 PM Jonathan Behrens <behrensj@...
>     <mailto:behrensj@...>> wrote:
>
>         If that is the intention, the text should be changed to "Returns
>         0 if the given SBI extension ID (EID) is not available, or an
>         *implementation defined* non-zero value if it is available".
>         Although, if the extensions aren't defining any meaning to the
>         various possible non-zero values, I personally don't see why we
>         shouldn't change it to "returns one if it is available".
>
>
>     I think allowing implementation-defined nonzero rather than
>     requiring it be 1 is OK, but I agree with your proposed wording change.
>
>
> Sounds good to me as well. I will make the change.

Why should the value be implementation specific and not extension specific?

I would prefer if the specification would provide extension specific
unique return values instead of introducing ambiguity about possible
return values.

This also allows us to define further return values per extension if
needed in future. But currently all of these values can be defined as 1.

We just have to add this value 1 to each extension description.

Best regards

Heinrich

>
>
>         Jonathan
>
>         On Wed, Jan 12, 2022 at 3:32 PM Atish Kumar Patra
>         <atishp@... <mailto:atishp@...>> wrote:
>
>             On Wed, Jan 12, 2022 at 10:59 AM Jonathan Behrens
>             <behrensj@... <mailto:behrensj@...>> wrote:
>              >
>              > If I understand correctly, per the description of
>             `sbi_probe_extension`, each of the extensions are supposed
>             to specify an "extension-specific non-zero value" to return
>             if they are available. However, right now I don't think any
>             of them do. Is this something that should be fixed?
>              >
>
>             The description says "Returns 0 if the given SBI extension
>             ID (EID) is
>             not available, or an extension-specific non-zero value if it is
>             available"
>             The specification says it should be non-zero as the value "0"
>             indicates non-availability of the extension. The exact
>             return value
>             should be an implementation detail.
>
>              > Jonathan
>              >
>              > On Wed, Jan 12, 2022 at 1:44 PM atishp via
>             lists.riscv.org <http://lists.riscv.org>
>             <atishp=rivosinc.com@...
>             <mailto:rivosinc.com@...>> wrote:
>              >>
>              >> I just realized that the below email was not delivered
>             to unix
>              >> platform mailing list and
>              >> linux-riscv mailing list because of the attachment.
>             Reseeding it again
>              >> without the
>              >> attachment. Apologies for the noise.
>              >>
>              >>
>             -----------------------------------------------------------------------------------------------
>              >> We are delighted to announce the start of the public
>             review period for
>              >> the Non-ISA Supervisor Binary Interface (SBI)
>             specification. The
>              >> SBI specification is considered as frozen now as per the
>             RISC-V International
>              >> policies.
>              >>
>              >> The review period begins today, Monday Jan 10, and ends
>             on Monday
>              >> Jan 24 (inclusive).
>              >>
>              >> The specification can be found here
>              >>
>             https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v1.0-rc1/riscv-sbi.pdf
>             <https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v1.0-rc1/riscv-sbi.pdf>
>              >>
>              >> which was generated from the source available in the
>             following GitHub
>              >> repository:
>              >> https://github.com/riscv-non-isa/riscv-sbi-doc
>             <https://github.com/riscv-non-isa/riscv-sbi-doc>
>              >>
>              >> To respond to the public review, please either reply to
>             this email or
>              >> send comments to the platform mailing list[1] or add
>             issues to the
>              >> SBI GitHub repo[2]. We welcome all input and appreciate
>             your time and
>              >> effort in helping us by reviewing the specification.
>              >>
>              >> During the public review period, corrections, comments, and
>              >> suggestions, will be gathered for review by the Platform
>             HSC members. Any
>              >> minor corrections and/or uncontroversial changes will be
>             incorporated
>              >> into the specification. Any remaining issues or proposed
>             changes will
>              >> be addressed in the public review summary report. If
>             there are no
>              >> issues that require incompatible changes to the public
>             review
>              >> specification, the platform HSC will recommend the updated
>              >> specifications be approved and ratified by the RISC-V
>             Technical
>              >> Steering Committee and the RISC-V Board of Directors.
>              >>
>              >> SBI specification is non-ISA specifications and will
>             evolve over time
>              >> with new extensions as long as they are backward
>             compatible. Any such
>              >> proposals for new extensions can be included in the
>             future releases
>              >> after proper discussions in the platform working group
>             meetings.
>              >>
>              >> Thanks to all the contributors for all their hard work.
>              >>
>              >> [1] tech-unixplatformspec@...
>             <mailto:tech-unixplatformspec@...>
>              >> [2]
>             https://github.com/riscv-non-isa/riscv-sbi-doc/issues
>             <https://github.com/riscv-non-isa/riscv-sbi-doc/issues>
>              >>
>              >> Regards,
>              >> Atish Patra
>              >>
>              >>
>              >>
>              >>
>              >>
>