Everything old is new again?

On Sat, Aug 10, 2019 at 7:11 PM Cyber Fonic <cyberfo...@gmail.com> wrote:

> The emergent problem with IoT is the lack of security.  From my
> understanding of Plan9's architecture. 9p protocol and the "root-less"
> security model suggests to me that a Plan9 swarm of IoT devices could be
> the "killer app" where Plan9 emerges on the strength of the vision of
> decades ago.  Looking at other RT OSes the security models are often bolted
> on.  Plan9 worked well on IBM PC era hardware. An ESP-32 has more resources
> and better networking than the early PCs.  From my tinkering and reverse
> engineering of IoT devices, almost all use 8266 based WiFi and often in
> conjunction with a uController. An ESP-32 is dual processor and with
> sufficient I/O for most simple tasks.  With IoT, in general, you don't need
> a lot of I/O, you simply throw more CPUs into the mix.
>
> On Sat, 10 Aug 2019 at 08:55, Skip Tavakkolian <skip.tavakkol...@gmail.com>
> wrote:
>
>> I'm not sure if the effort would be worth it; but if you add support for
>> esp32, I think it would be better for the os to be something like the one
>> you had in kencc for AVR (*) or possibly Russ' libtask, rather than Plan 9.
>> Staying with FreeRTOS would need removal of GCC specific things from OS and
>> dealing with lots of drivers in C++.
>>
>> The Cortex-M based mpus (e.g. Teensy 4 with Cortex M7 @ 600MHz) seem more
>> appropriate for an "embedded" Plan 9.
>>
>> (*) for those who have not seen it, it is here:
>> % ls -l /n/sources/contrib/forsyth/avr*
>> --rw-rw-r-- M 518 bootes sys 251227 Sep  4  2011
>> /n/sources/contrib/forsyth/avr.9gz
>>
>> On Fri, Aug 9, 2019 at 2:36 PM Charles Forsyth <charles.fors...@gmail.com>
>> wrote:
>>
>>> Since the resources are small if not tiny, a little systems analysis and
>>> design is probably needed, but it looks like a bit of fun, until the
>>> inevitable moment of "why am I here?".
>>>
>>> On Fri, Aug 9, 2019 at 4:50 PM Charles Forsyth <
>>> charles.fors...@gmail.com> wrote:
>>>
>>>> The device I've got is ESP32-WROOM-32. None of the boards I've seen
>>>> that use it bother with external memory,
>>>> so memory is limited, especially the way it's partitioned.
>>>>
>>>> On Fri, Aug 9, 2019 at 3:50 PM Charles Forsyth <
>>>> charles.fors...@gmail.com> wrote:
>>>>
>>>>> The ESP32 has got several MMUs. The characteristics are different
>>>>> depending on the part that a given MMU accesses (flash, ROM, SRAM, 
>>>>> external
>>>>> memory).
>>>>> Some things are accessed using Memory Protection Units instead, which
>>>>> control access by Process ID, but don't do mapping. Others including some
>>>>> of the SRAMs are accessed through
>>>>> an MMU that can do virtual to physical mapping. The MMUs for internal
>>>>> SRAM0 and 2 choose protection for a given physical page as none, one or 
>>>>> all
>>>>> of PIDs 2 to 7, with the virtual address that
>>>>> maps to it. PIDs 0 and 1 can access everything. PID 0 can execute
>>>>> privileged instructions.
>>>>> A large chunk of SRAM (SRAM 1) has only Memory Protection and no
>>>>> translation. The external memory MMU is the most general (most
>>>>> conventional).
>>>>>
>>>>> On Fri, Aug 9, 2019 at 3:19 PM Bakul Shah <ba...@bitblocks.com> wrote:
>>>>>
>>>>>> esp32 doesn’t have an mmu, right?
>>>>>>
>>>>>> On Jul 26, 2019, at 03:30, Charles Forsyth <charles.fors...@gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>> I was thinking of doing that since I've got an ESP-32 for some reason
>>>>>>
>>>>>> On Fri, Jul 26, 2019 at 7:38 AM Cyber Fonic <cyberfo...@gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> I was reading the post Why Didn't Plan 9 Succeed
>>>>>>> <https://news.ycombinator.com/item?id=20527650> on Hacker News.
>>>>>>>
>>>>>>> Made me think that Plan 9 for IoT system of systems could be viable.
>>>>>>>
>>>>>>> To that end, ESP-32 modules look capable enough to run Plan 9, but
>>>>>>> is there a Plan 9 C compiler for Xtensa ISA CPUs?
>>>>>>>
>>>>>>>

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