This might be of some interest - https://hackaday.com/2021/02/24/real-time-os-basics-picking-the-right-rtos-when-you-need-one/

Also - if you're interested in minimal OS with easy low-level access you could do worse than investigating RISC OS. Get a Pi, download the package from riscos direct )https://www.riscosdev.com/direct/) and play.

> On 2021-02-26, at 4:46 PM, ken.dickey at whidbey.com wrote:
> 
> Liam wrote:
> 
>> I do not know much about the whole L4 family but what little I know
> some of the existing OSes based upon them were very vaguely Unix-ish.
> That's precisely what I'm trying to move away from.
> 
> • I do not know if SEL4 has working multiprocessor support. I know
> that QNX does, which demonstrates that a Unix-like true microkernel
> can do this; but I also believe that Minix 3 so far lacks one, and
> lacks some APIs needed for POSIX and xNix compatibility. This is not
> an easy thing to do.
> ..
> 
> Right.  I am thinking of expanding outward from Genode ( https://genode.org/about/index ), start with a small (non-Unix) OS which runs on (some of) x86/ARM64/RISC-V which can be used as a bootstrap for Smalltalk->Native runtime, then replace services written in C to services written in Smalltalk initially with the same API, but later re-imagined.  An ultra-secure OS which has the right basics for hotplug/live updates.  Add eMail & Web browsing after getting core St GUI up.
> 
> This is pretty much a scratch effort.  Some C at first, particularly in the microkernel (e.g. seL4) but this is minimal and kinda like changing FPGA gates.
> 
> We are probably "agreeing loudly" on most of this, particularly given my ignorance of Oberon.
> 
> Later,
> -KenD
> 
> 


tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
Strange OpCodes: RCR: Rewind Card Reader