Re: Sun4/110 "Panic: Crazy Interrupts"

[Samuel Furtaw <samfurtaw%gmail.com@localhost>]

Whoops, I forgot to include the mailing list - here is my message:
Hello again!

I commented out that block and compiled again - I had to add
-Wno-unused to the generated Makefile to get it to build since it
didn't like 'bt' and 'i' hanging around unused.

It looks like the stray interrupts still happen, and we still panic in
that further along spot from before. So I assume we'd just disable
these interrupts?

Thanks,
Samuel

On Thu, Apr 18, 2024 at 5:30 PM Samuel Furtaw <samfurtaw%gmail.com@localhost> wrote:
>
> Hello again!
>
> I commented out that block and compiled again - I had to add
> -Wno-unused to the generated Makefile to get it to build since it
> didn't like 'bt' and 'i' hanging around unused.
>
> It looks like the stray interrupts still happen, and we still panic in
> that further along spot from before. So I assume we'd just disable
> these interrupts?
>
> Thanks,
> Samuel
>
> On Thu, Apr 18, 2024 at 6:52 AM Julian Coleman <jdc%coris.org.uk@localhost> wrote:
> >
> > Hi,
> >
> > > The panic DDB isn't wanting to take input for me, so I added printf's
> > > to find the line number. It looks like we crash at line 304:
> > > ```
> > > bt->bt_addr = 0
> > > ```
> >
> > Looking at cgfourattach, there didn't appear to be much apart from the DAC
> > initialisation, but I'm still somewhat surprised that the SZERR comes from
> > here.
> >
> > We define these registers (bt_regs):
> >
> >   https://nxr.netbsd.org/xref/src/sys/dev/sun/btreg.h#71
> >
> > as integers, but I wonder if they are only readable/writeable as 8-bit
> > quantities on P4 framebuffers.  If so, I wonder how this worked in the
> > past.
> >
> > I'm guessing that we could either (or both):
> >
> >   a) alter the CG4/P4 code to only read/write 8-bit quantities
> >   b) look at the Sun3 code (especially the P4 register definition:
> >       https://nxr.netbsd.org/xref/src/sys/arch/sun3/dev/p4reg.h
> >     and disable interrupts.  After all, we're not going to use them.
> >
> > As a quick hack, commenting out the BT DAC setup might get us past this
> > crash and to check if attaching the CG4 driver does help with the interrupt
> > problem.  If so, we could work on a), if not we can fall back to b).
> >
> > Can you comment out the lines with:
> >
> >   bt->bt_addr = 0;
> >   for (i = 0; i < 256 * 3 / 4; i++)
> >     ((char *)&sc->sc_cmap)[i] = bt->bt_cmap >> 24;
> >   BT_INIT(bt, 24);
> >
> > and see if that gets us further along?
> >
> > Regards,
> >
> > Julian
> >
> > PS.  I don't have access to my development environment at the moment, so I'm
> > not able to easily send patches.