On Tue, Feb 07, 2023 at 10:15:22AM -0800, Atish Patra wrote: > On Tue, Feb 7, 2023 at 10:05 AM Conor Dooley <conor@xxxxxxxxxx> wrote: > > On Fri, Feb 03, 2023 at 05:31:01PM +0530, Anup Patel wrote: > > > On Fri, Feb 3, 2023 at 5:54 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote: > > > > > > > > On Fri, 27 Jan 2023 23:27:32 PST (-0800), apatel@xxxxxxxxxxxxxxxx wrote: > > > > > We have two extension names for AIA ISA support: Smaia (M-mode AIA CSRs) > > > > > and Ssaia (S-mode AIA CSRs). > > > > > > > > This has pretty much the same problem that we had with the other > > > > AIA-related ISA string patches, where there's that ambiguity with the > > > > non-ratified chapters. IIRC when this came up in GCC the rough idea was > > > > to try and document that we're going to interpret the standard ISA > > > > strings that way, but now that we're doing custom ISA extensions it > > > > seems saner to just define on here that removes the ambiguity. > > > > > > > > I just sent > > > > <https://lore.kernel.org/r/20230203001201.14770-1-palmer@xxxxxxxxxxxx/> > > > > which documents that. > > > > > > I am not sure why you say that these are custom extensions. > > > > > > Multiple folks have clarified that both Smaia and Ssaia are frozen > > > ISA extensions as-per RVI process. The individual chapters which > > > are in the draft state have nothing to do with Smaia and Ssaia CSRs. > > > > > > Please refer: > > > https://github.com/riscv/riscv-aia/pull/36 > > > https://lists.riscv.org/g/tech-aia/message/336 > > > https://lists.riscv.org/g/tech-aia/message/337 > > > > All of these links seem to discuss the draft chapters somehow being > > incompatible with the non-draft ones. I would very expect that that, > > as pointed out in several places there, that the draft chapters > > finalisation would not lead to meaningful (and incompatible!) changes > > being made to the non-draft chapters. > > > > Here is the status of all RVI specs. It states that the Smaia, Ssaia > extensions are frozen (i.e. public review complete). > https://wiki.riscv.org/display/HOME/Specification+Status > > I have added stephano/Jeff to confirm the same. > > AFAIK, IOMMU spec is close to the public review phase and should be > frozen in this or next quarter. > IIRC, this chapter in AIA will be frozen along with IOMMU spec. > > Anup: Please correct me if that's not correct. > > > Maybe yourself and Palmer are looking at this from different > > perspectives? Looking at his patch from Friday: > > https://lore.kernel.org/linux-riscv/20230203001201.14770-1-palmer@xxxxxxxxxxxx/ > > He specifically mentioned this aspect, as opposed to the aspect that > > your links refer to. > > > > Surely a duo-plic, if that ever comes to be, could be detected from > > compatible strings in DT or w/e - but how do you intend differentiating > > between an implementation of S*aia that contains the IOMMU support in > > Chapter 9 in a finalised form, versus an implementation that may make > > "different decisions" when it comes to that chapter of the spec? > > We will most likely have an extension specific to iommu spec as well. Right, but unless I am misunderstanding you, that is an extension for the IOMMU spec, not for Chapter 9 of the AIA spec? I would say that it is likely that if you have AIA and IOMMU that you'd want to be implementing Chapter 9, but that would not appear sufficient to draw a conclusion from. Maybe the RVI lads that you've added (or Anup for that matter!) can clarify if there is a requirement that if you do AIA and IOMMU that you must do Chapter 9. If not, my prior question about a differentiation mechanism still applies I think! > > I thought that would be handled by extension versions, but I am told > > that those are not a thing any more. > > If that's not true, and there'll be a version number that we can pull in > > from a DT and parse which will distinguish between the two, then please > > correct my misunderstanding here!
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