Strange panic on ppc64

[Justin Hibbits]

On Mon, Jun 10, 2013 at 6:31 AM, Nathan Whitehorn <nwhitehorn at freebsd.org>wrote:

> On 06/10/13 08:20, Nathan Whitehorn wrote:
> > This is now getting interesting. Reading the tea leaves, what has
> > happened is that the kernel has called into Open Firmware. Open Firmware
> > has then crashed early on, before setting up its own trap handlers,
> > which has then flung you back into FreeBSD's handlers with a totally
> > bogus environment, causing a second panic, which then causes a *third*
> > panic when trying to acquire a lock. It would be interesting to know
> > what the OF environment looked like and what commands it was trying to
> > execute (in r3), but that may be tricky to get...
> > -Nathan
> > _______________________________________________
>
> One other point: you can trace this pretty easily by just putting
> something like:
>
> if (pmap_bootstrapped) printf("Open Firmware call %p\n", args);
>
> in the top of openfirmware(). If I understood the debugger output
> correctly, something should be making a firmware call immediately before
> the crash.
>
> As a random guess about what is happening, it is possible OF is trying
> to allocate memory for itself. We just ignore the possibility that it
> might want to do that at present, but that is not necessarily a good
> assumption.
> -Nathan
>

I added that, both on entry and exit.  I also have it printing out the name
of the ofw call, since the first item is always a pointer to the name.
I'll be able to report more tomorrow.

- Justin