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.
