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Comment by barkingcat | Hacker News Reader

For embedded / iot usage, one major issue is device support

It does contain raspberry pi's but the list isn't all that great.

I had trouble finding 32 bit ARM precompiled binary distributions from ubuntu (that is not a rpi), and had to compile my own kernel + inline it with debian to get 32 bit arm support.

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Smallest thing I've found is a FreeScale SOC running a Cortex-A7.

Cortex M* lack MMU, which is necessary for any normal linux distro. Cortex M0 and M4 are just beefy microcontrollers.

You're correct. I'll revise.

Can you run Linux on a Cortex-M, which is basically a microcontroller, instead of a Cortex-A that has a MMU? I don't think it's possible.

Yes, you can actually. I haven't done this myself, but there are defconfigs for mmu less devices (stm32f4 series for instance). You need some more RAM though, but most evaluation kits don't provide this. Have a look here: https://elinux.org/STM32 I'm planning to give this a spin on an EVK that I got from work if I find the time.

Linux? yes. Popular distro? not really. Lack of MMU means that all the processes (and shared objects) use the same memory space, so unless you have some way of randomizing where things go (like SELinux), two processes will step on each other's data (MPU will not trigger segfault, as both are allowed to r/w same addr - IIUC). But even when using randomizing, you're playing russian rulette.

Do you think there is any practical use to it instead of running just an embedded OS? Driver support maybe?

drivers, as you said, for filesystems for instance, syscalls available that we know and love :), somewhat easier deployment (elf instead of raw bin), other abstractions that linux provides, multiprocessing (if done carefully), real multithreading,

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