Re: Help: How do I make a machine with 2 separate ARM SoC's?

[Cédric Le Goater]

Hello Peter M.,

[ ... ]

> Another device that does some moderately complicated things with
> MemoryRegions is the hw/arm/armsse.c SoC, which has several CPUs
> and has some per-CPU devices.
>
> I think we have not thus far had a model of a board where different
> CPUs see radically different things (only ones where they can see
> minor differences), so you'll probably run into places where the
> APIs are a bit clunky (and we can perhaps have a go at making
> them a bit less so). What I would do is make the system_memory
> container be used by whatever is the "main" application processor
> SoC in your board. If the two SoCs really see absolutely different
> worlds with no shared devices at all, then you'll want to create
> a new empty container for the second SoC. If they do have some
> board-level shared devices, then you'll want to do something a little
> more complicated with aliases.
>
> If you find the SoC device models you're using hardcode use of
> system_memory or address_space_memory you should treat those as
> bugs to be fixed. Other loose ends (like monitor commands that
> assume the system address space) can be ignored: having those
> operate on the 'application processor' SoC is fine, I think.

On the CPU topic, I think we will need to change the GIC device
to stop using qemu_get_cpu() in the CPU interface init routine
and in the GIC realize routine, since this is global to the machine.
I am having the same problem when trying to model a multi SoC board
with a GIC device on each chip.

What would be a good approach to loop only on the CPUs related
to a GIC device ? Could we tag the CPUs and the GIC in some way
to filter the unrelated CPUs ? Or pass a CPU list to the GIC
device ?

Thanks,

C.

> Overall, this is definitely doable but will involve a fair
> about of slogging through territory where nobody has yet
> broken a trail for you :-)
>
> -- PMM