Status of the various RISC-V specification and policy

[Palmer Dabbelt]

On Mon, 27 Sep 2021 08:57:15 PDT (-0700), markhimelstein at riscv.org wrote:
> the words in this document : 
>
> https://wiki.riscv.org/plugins/servlet/mobile?contentId=13098230#content/view/13098230
>
> make it very clear when changes are allowed or not and likely or not.
>
> if you think the verbiage is somehow ambiguous please help us make it better.

I'm not really worried about changes, I'm worried about a committment to 
future compatibility.  When we take code into the kernel (and most other 
core systems projects) we're taking on the burden of supporting (until 
someone can prove there are no more users), which is very difficult to 
do when the ISA changes in an incompatible fashion.  The whole point of 
agreeing on the frozen thing was that it gave us a committment from the 
specifcation authors that the future ISA would be compatible with th 
frozen extensions.

We're already in this spot with the V extension and the whole stable 
thing, this definitaion of frozen looks very much like what was has led 
to the issues there.  Saying the spec won't change really isn't 
meaningful, it's saying future specs will be compatible that's 
important.  Nothing in this whole rule touches on compatibility, and I 
really don't want to end up in a bigger mess than we're already in.

(Also: some PGE subcontractor drove a crane into my house, so things are 
a bit chaotic on my end.  If you have that list of what's officially 
frozen, can you send it out?  I'll try to take a look ASAP, as then I 
can at least focus the discussion on what's relevant right now.)

>
> Mark
> --------
> sent from a mobile device. please forgive any typos.
>
>> On Sep 27, 2021, at 8:50 AM, Palmer Dabbelt <palmer at dabbelt.com> wrote:
>> 
>> On Tue, 21 Sep 2021 17:20:17 PDT (-0700), atishp at atishpatra.org wrote:
>>> Hi All,
>>> Please find the below email from Stephano about the freeze announcement for
>>> various RISC-V specifications that will be part of privilege specification
>>> v1.12.
>>> All the review discussions are happening in the isa-dev mailing list. The
>>> review period will be open for 45 days ending Sunday October 31, 2021.
>>> 
>>> I just want to highlight the fact that the *H*, *V, SvPBMT, CMO extensions
>>> are frozen now. *This will help us merge some patches that have been
>>> present in the mailing list for a while.
>>> 
>>> Here are the ratification policy and extension life cycle documents present
>>> in the public. If you have any questions regarding this, please check with
>>> Mark/Stephano (cc'd).
>>> 
>>> Ratification policy:
>>> https://docs.google.com/document/d/1-UlaSGqk59_myeuPMrV9gyuaIgnmFzGh5Gfy_tpViwM/edit
>>> 
>>> Extension life cycle:
>>> https://docs.google.com/presentation/d/1nQ5uFb39KA6gvUi5SReWfIQSiRN7hp6z7ZPfctE4mKk/edit#slide=id.p1
>> 
>> I'm still buried after Plumbers, but one of the bits on my TODO list was to look throught the new definitions for frozen and stable.  Nothing in this extension life cycle talks about the point at which compatibility will be maintained, which was really the central point behind frozen before.
>> 
>> Are there more concrete definitions somewhere?