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

[Mark Cave-Ayland]

On 17/10/2021 17:56, Laurent Vivier wrote:

> Le 17/10/2021 à 12:00, Mark Cave-Ayland a écrit :
> ...
> > I've just tried this on Linux, and it seems to work okay although I get several 
> > copies of the
> > register dump on the console for a single invocation of "info nmi" e.g.
> >
> > [    4.610000] Non-Maskable Interrupt
> > [    4.610000] Modules linked in: mac_esp(+) esp_scsi macsonic
> > [    4.610000] PC: [<00002dc0>] arch_cpu_idle+0x4/0x6
> > [    4.610000] SR: 2000  SP: (ptrval)  a2: 00395314
> > [    4.610000] d0: 00000000    d1: 00000002    d2: 0004b492    d3: 00392000
> > [    4.610000] d4: 00000000    d5: 00000000    a0: 00392000    a1: 00395314
> > [    4.610000] Process swapper (pid: 0, task=(ptrval))
> > [    4.610000] Frame format=0
> > [    4.610000] Stack from 00393f9c:
> > [    4.610000]         0004b540 00000431 0040ee22 0004b4c4 0002bf6a 004005f0 
> > 00393ff8 0004b714
> > [    4.610000]         0003e23a 0029c518 000000c2 0040eb54 3dc1e5d0 00000000 
> > 0004ff74 0003efe2
> > [    4.610000]         003f4e92 00000000 00000040 00000000 00000000 00000000 
> > 0040ee22 00000000
> > [    4.610000]         003f3872
> > [    4.610000] Call Trace: [<0004b540>] do_idle+0x7c/0xd2
> > [    4.610000]  [<0004b4c4>] do_idle+0x0/0xd2
> > [    4.610000]  [<0002bf6a>] kernel_thread+0x0/0x26
> > [    4.610000]  [<004005f0>] __alloc_bootmem+0x0/0x38
> > [    4.610000]  [<0004b714>] cpu_startup_entry+0xe/0x12
> > [    4.610000]  [<0003e23a>] find_task_by_pid_ns+0x0/0x22
> > [    4.610000]  [<0029c518>] rest_init+0x78/0x82
> > [    4.610000]  [<0004ff74>] printk+0x0/0x18
> > [    4.610000]  [<0003efe2>] parse_args+0x0/0x2c2
> > [    4.610000]  [<003f4e92>] start_kernel+0x43e/0x448
> > [    4.610000]  [<003f3872>] _sinittext+0x872/0x11f8
> > [    4.610000] Code: bc00 0060 f210 f0ff 7001 60cc 4e72 2000 <4e75> 2079 003b 
> > fc6c 4a88 6702 4e90
> > 60fe 2079 003b fc68 4a88 6702 4e90 60fe 2f0c
> >
> > (repeated 7 or 8 times)
> >
> > MacsBug seems to handle this better: as soon as the NMI is triggered, MacsBug 
> > opens and displays
> > "NMI" both if the programmer switch GPIO is held active, or pulsed as 
> > implemented in the patch. When
> > using the above patch, subsequent NMI triggers do not display "NMI" or change 
> > MacsBug in any visible
> > way which suggests that once the NMI is triggered, the NMI is ignored until the 
> > programmers switch
> > GPIO is inactive once again.
> >
> > Do you see the repeated register output in Linux for a single press of the 
> > programmers switch on a
> > real Quadra 800? It may be that Linux could be improved by having similar logic.
>
> In fact, register output is repeated while I keep the button pressed (5.14 
> kernel provided by Finn)
>
> If I press and release one (or several) time(s) before the end of the first 
> output I have only one
> output.

Thanks, that makes sense - my guess is that the repeated output in QEMU is just a 
symptom of the QEMU machine being much faster than the real one.


ATB,

Mark.