Re: [PATCH] Add direct memory access synchronize extension

David Kruckemyer

Hi all,

My apologies as I just got wind of this discussion (I was unable to attend the last few CMO TG meetings due to travel). I think we should sync up on the CMO TG and SBI/platform efforts since there seems to be a bit of disconnect.

Regarding the CMO TG goals, we have intended to get a basic subset of operations into the profile/platform specifications for this year. The "phase 1" status is listed here:

Though honestly, a bit of this is out of date already, so expect some clarification in the coming days (just need to do some terminology cleanup).

Please do not hesitate to reach out to me with any questions (or to post questions to the the CMO TG mailing list: tech-cmo@... )


On Mon, Jun 7, 2021 at 2:35 AM Nick Kossifidis <mick@...> wrote:
Στις 2021-06-07 07:03, Anup Patel έγραψε:
> Let's have a simple SBI DMA sync extension in SBI v0.4 spec.
> The shared code pages between M-mode and S-mode will have it's own
> Challenges and we will have to define more stuff in SBI spec to support
> this (see above).

Totally agree with you, I just thought it'd be a good opportunity to
bring this up so that we can discuss it at some point, let's have
something that works and we can optimize it later on.

> It seems CMO extension might freeze sooner than we think (others can
> comment on this). If CMO extension is frozen by year end then we can
> trap-n-emulate CMO instructions instead of SBI DMA sync extension. If
> it does not freeze by year end then we will have to go ahead with
> SBI DMA sync extension as stop-gap solution.

The CMOs TG has a meeting today, I'll try and join and ask for updates
on this.

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