4 ms·

Pico is a microcontroller whose Cortex-M0+ cores lack a memory management unit for virtual memory (considered essential for a full-fledged OS like Linux). But c

Pico is a microcontroller whose Cortex-M0+ cores lack a memory management unit for virtual memory (considered essential for a full-fledged OS like Linux). But can run FreeRTOS on it...memory usages are 236 bytes for the scheduler, 76 bytes + queue storage area for each queue, and 64 bytes plus task stack size for each task, plus 5 to 10 KBytes of ROM.[1] [1] https://freertos.org/FAQMem.html https://freertos.org/FAQMem.html

moffkalast 3y ago
Yeah I figured there might be a rub somewhere otherwise it would already be a thing, but since it's technically an ARM it sounded vaguely promising. What about a 32 bit build? I think those used to be able to work with without virtual addresses.
- NegativeLatency 3y ago
  https://unix.stackexchange.com/questions/190350/mmu-less-kernel https://unix.stackexchange.com/questions/190350/mmu-less-ker...
  - em3rgent0rdr 3y ago
    aha, and this reminds me about μClinux [1] which targets microcontrollers without a MMU. I installing it on 2005 iPod Classic 5G, and was able to then put a gameboy emulator on it. https://en.wikipedia.org/wiki/%CE%9CClinux https://en.wikipedia.org/wiki/%CE%9CClinux
    - em3rgent0rdr 3y ago
      Though μClinux project seems dead, however the key component of that is a ELF to bFLT (binary flat) converter [1] for no-mmu Linux targets, which is alive on github [2]. [1] https://web.archive.org/web/20120301074213/https://retired.beyondlogic.org/uClinux/bflt.htm https://web.archive.org/web/20120301074213/https://retired.b... [2] https://github.com/uclinux-dev/elf2flt https://github.com/uclinux-dev/elf2flt
yjftsjthsd-h 3y ago
There's also inferno, which is more or less a full unix-like that can run on the pico ( https://news.ycombinator.com/item?id=37393993 https://news.ycombinator.com/item?id=37393993 ) and on the Teensy and some other microcontrollers ( https://dboddie.gitlab.io/inferno-diary/index.html https://dboddie.gitlab.io/inferno-diary/index.html )
rzzzt 3y ago
ELKS supported MMU-less operation on 8088 and 80286 machines, but I don't think an ARM port exists: https://github.com/ghaerr/elks https://github.com/ghaerr/elks
gorkish 3y ago
The popular way to shorehorn modern linux onto a MMU-less microcontroller is to build a a RISC V system emulator and run uClinux on that; you can also emulate the MMU and run regular kernels if you have sufficient resources. It has been done on ESP32 with sufficient RAM; Pico would need additional hardware though in the form of something like QSPI RAM, and of course it would be very slow.

moffkalast 3y ago

Yeah I figured there might be a rub somewhere otherwise it would already be a thing, but since it's technically an ARM it sounded vaguely promising. What about a 32 bit build? I think those used to be able to work with without virtual addresses.

NegativeLatency 3y ago
https://unix.stackexchange.com/questions/190350/mmu-less-kernel https://unix.stackexchange.com/questions/190350/mmu-less-ker...
- em3rgent0rdr 3y ago
  aha, and this reminds me about μClinux [1] which targets microcontrollers without a MMU. I installing it on 2005 iPod Classic 5G, and was able to then put a gameboy emulator on it. https://en.wikipedia.org/wiki/%CE%9CClinux https://en.wikipedia.org/wiki/%CE%9CClinux
  - em3rgent0rdr 3y ago
    Though μClinux project seems dead, however the key component of that is a ELF to bFLT (binary flat) converter [1] for no-mmu Linux targets, which is alive on github [2]. [1] https://web.archive.org/web/20120301074213/https://retired.beyondlogic.org/uClinux/bflt.htm https://web.archive.org/web/20120301074213/https://retired.b... [2] https://github.com/uclinux-dev/elf2flt https://github.com/uclinux-dev/elf2flt

yjftsjthsd-h 3y ago

There's also inferno, which is more or less a full unix-like that can run on the pico ( https://news.ycombinator.com/item?id=37393993 https://news.ycombinator.com/item?id=37393993 ) and on the Teensy and some other microcontrollers ( https://dboddie.gitlab.io/inferno-diary/index.html https://dboddie.gitlab.io/inferno-diary/index.html )

rzzzt 3y ago

ELKS supported MMU-less operation on 8088 and 80286 machines, but I don't think an ARM port exists: https://github.com/ghaerr/elks https://github.com/ghaerr/elks

gorkish 3y ago

The popular way to shorehorn modern linux onto a MMU-less microcontroller is to build a a RISC V system emulator and run uClinux on that; you can also emulate the MMU and run regular kernels if you have sufficient resources. It has been done on ESP32 with sufficient RAM; Pico would need additional hardware though in the form of something like QSPI RAM, and of course it would be very slow.