What I want to do.

[Michael Grunditz]

In message <CAO3d8HiWwzqnWE+GqGYOhWaJN6KOmiidFBLB6rJC+x2_Mx7Btw at mail.gmail 
.com>
          Edoardo Mantovani <mantovani.edoardo18 at gmail.com> wrote:

> Hi Michael,
> Sorry if I am late, but only now I had time for read this:
> http://www.update.uu.se/~micken/ronetbsd.html

Thanks.

> Extremely interesting and, at the same time, extremely fast to read,
> I have only one question:
> Have you created two more GRUB partitions (separate one from each other) to
> boot the 2 systems?

ARM doesn't use GRUB , it uses u-boot. I have only done this for RK3399 
SoC. It started with the fact that the cpu was continuing running after I 
started RISC OS on the A72 core 0. I figured that this could be (ab)used 
to run a second system.

> it would be interesting to know more about the boot phase because honestly
> I can't understand if there could be problems related to the probe of the
> connected devices (like, if the 2 OS at the same time probe via PCI for the
> same hardware at the same time, could an error occur? for example something
> like "device busy, impossible to connect with it"?)
> It would be very interesting for an article about an advanced Fault
> Injection methodology that I've been thinking about for a long time.

I am very careful not to use the same devices from the different OSes. I 
am using what is called affinity routing in the interrupt "chip" (General 
Interrupt Controller). It does route the interrupts to different CPUs. 
That means that only the supported hardware interrupts.

I have written a couple of drivers for NetBSD in order to use the WiMP in 
RISC OS (the desktop) as input and display devices.

The NetBSD project is the first of it kind ,according to NetBSD 
developers. There are other uses that do run a realtime system on a small 
cpu. But I haven't found anything that does run full scale OSes without 
virtualization  . Correct me if I am wrong!

> Let me know,
> Regards,
> Edoardo Mantovani, 2021

<big snip>

You can in theory run 4 OSes on a quad core cpu. But the OSes needs to be 
able to run quite  limited.


Best regards,

Michael


-- 
       Michael Grunditz
Sent from my RISC OS workstation..