Re: [PATCH 8/8] q800: add NMI handler

[Laurent Vivier]

Le 15/10/2021 à 22:12, Mark Cave-Ayland a écrit :
> On 15/10/2021 09:40, Laurent Vivier wrote:
> 
>> Le 13/10/2021 à 23:21, Mark Cave-Ayland a écrit :
>>> This allows the programmer's switch to be triggered via the monitor for 
>>> debugging
>>> purposes. Since the CPU level 7 interrupt is level-triggered, use a timer 
>>> to hold
>>> the NMI active for 100ms before releasing it again.
>>
>> I'm wondering if Qemu provides another way to have a level-triggered 
>> interrupt in this case.
>>
>> I' tried to see if keeping the button pressed on a mac kept the IRQ up (as 
>> QMP NMI does), but a real
>> mac is too slow and has to many things to display it was not really 
>> conclusive...
> 
> When writing the patch I rebased the outstanding MacOS patches onto the 
> branch, installed Macsbug
> into MacOS and used "info nmi" to break into it.
> 
> Testing glue_nmi() with:
> 
>   GLUE_set_irq(s, GLUE_IRQ_IN_NMI, 1);
>   GLUE_set_irq(s, GLUE_IRQ_IN_NMI, 0);
> 
> i.e. a simple pulse didn't launch MacsBug at all. Keeping the NMI high 
> launches MacsBug (which is
> usable) but then as soon as you exit MacsBug with ES, MacsBug breaks 
> immediately again making it
> impossible to return to the Finder. Adding the timer allows launching MacsBug 
> and then
> exiting/re-entering MacsBug again on demand as expected.
> 

I think we have to mimic the finger pressing the button..

By the way, NMI should also dumps the CPU registers under linux.

Reviewied-by: Laurent Vivier <laurent@vivier.eu>