On 13/11/2019 10:31, The Natural Philosopher wrote:
> On 13/11/2019 10:23, Areligious Republican wrote:
>> Is there a Usenet news group for discussing ARM in
>> general?
>>
>> I've looked at comp.sys.arm but it looks moribund,
>> only 5 posts over the past year (from Eternal September
>> anyway)
>
> More online web based fora.
>
> But here is no bad place.
>
>

OK, I'll try you as it's really an RPi4 consideration ...

1. Out of interest, were there to be a 32 bit application
running under a 64 bit OS, what actually happens when an
interrupt comes along, andinterrupt that might have system-wide
importance?

Is it dealt with by the 32 bit IRQ / FIRQ mechanism or does
it switch back to the 64 bit?

2. And this is really an RPi4 consideration. Are the graphics
controled by messages left in the postbox, and if so, the full
grapics package, normally for the 32 vit Raspbian, would actually
be available to 64 bit code?

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