here's the SOC: https://documentation.espressif.com/esp32-p4_datasheet_en.html
I could not figure out what the MMU did, but it DOES have a lot of PMP regions (i.e. segments). I don't think it has privilege mode, but inferno won't care. On Mon, Sep 14, 2026 at 5:03 PM Charles Forsyth <[email protected]> wrote: > The MMU does not support page based virtual memory. I suspect that is a >> problem for plan9, unless there is a nommu option. > > > As someone suggested, Inferno's fine with that, or at least tolerates it. > What does the MMU do? > > On Mon, 14 Sept 2026 at 23:55, Joshua D. Boyd via 9fans <[email protected]> > wrote: > >> >> >> On September 14, 2026 4:03:48 PM EDT, Shawn Rutledge <[email protected]> >> wrote: >> >That looks like rather little memory (768k SRAM; 32MB “PSRAM” has some >> sort of catch - is it serial-attached and slow?) You’d have a chance with >> Inferno though: similar to David Boddie’s microcontroller ports >> https://github.com/dboddie/inferno-os (look at branches) except riscv >> instead of arm. I haven’t heard of a port to ESP-riscv chips being done >> yet. If the LoRa devices with nice screens and keyboards (like LilyGo >> T-Deck series) would start using the Risc-V ESP chips, I might be somewhat >> interested in that too. But I’m busy enough with the Plan 9 port for now, >> which is for Spacemit K1 and K3 so far (much more memory and performance). >> >> The PSRAM is serial attached. It should have its own MSPI bus for that, >> and should be good for a bit less than 200MB/s in bandwidth. >> >> The PSRAM does get mapped into memory space directly, and it does get >> cached. >> >> The MMU does not support page based virtual memory. I suspect that is a >> problem for plan9, unless there is a nommu option. > *9fans <https://9fans.topicbox.com/latest>* / 9fans / see discussions > <https://9fans.topicbox.com/groups/9fans> + participants > <https://9fans.topicbox.com/groups/9fans/members> + delivery options > <https://9fans.topicbox.com/groups/9fans/subscription> Permalink > <https://9fans.topicbox.com/groups/9fans/T925b60c1e0142973-M7e45e7f57d3e679eb64f5690> > ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/T925b60c1e0142973-M5156de1d17a6ab77886b37c3 Delivery options: https://9fans.topicbox.com/groups/9fans/subscription
