11.1 release CD image panics very early during boot on ppc.

[Jukka Ukkonen]

So, I tried setting debug.debugger_on_panic=1 and ”boot -v”.
The first time I tried the ofw did not see the full-HD display
which was connected to another system via a KVM switch at
that time. I only got the KVM switched to the correct system
only when I had got the booting stopped at the ofw prompt.
So, the early boot assumed a very traditional 80 columns by
25 to 30 lines display with a large font. Surprisingly the 11.1 CD
booted just fine. Obviously I wanted to double check and rebooted
the system. This time the display was connected via the KVM
switch to the system right from the start. The ofw obviously figured
out the true full-HD resolution and used a tiny font. When the kernel 
got control of the system it selected a bit larger font, showed some
of the autoconfig messages, and went down hard no matter whether
I set the debug.debugger_on_panic=1 or not.
This raises the obvious assumption that there must be something
going awry with how vt and ofw communicate and how they try to
control the display. Supposedly this could lead to mismanagement
of a large chunk of memory such that even the debugger is left
totally powerless when the crash happens. Because vt is new to 11.1
and the properly booting 10.4 uses sc, memory corruption seems
like a plausible explanation to the mysterious crash.

I hope this helps.

--jau


> On 17 Apr 2018, at 18.11, Justin Hibbits <jrh29 at alumni.cwru.edu> wrote:
> 
> Hi,
> 
>> On Sun, Apr 15, 2018 at 2:10 AM, Jukka Ukkonen <jau789 at gmail.com> wrote:
>> 
>> I had a bit of an accident with my old PowerMac G4 which had been
>> running FreeBSD-10.4. To fix the mess I had to boot the system from
>> a CD image. So, I decided to try 11.1 while at it. To my astonishment
>> and disappointment the 11.1 images (both CD and DVD) paniced
>> very early on during the boot. The messages flashed past the screen
>> so quickly that I cannot be really sure about anything, but it kind of
>> seemed like the issue might be yet another installment of the SPRG
>> related problems (in ofw_machdep.c) which have been troubling
>> ppc64 systems before.
>> The 10.4 CD image boots just fine on ppc.
>> 
>> --jau
> 
> Can you try booting with 'boot -v' and also setting at the loader
> debug.debugger_on_panic=1?  I think it's set to 0 on release ISOs, so
> this should let you get a screen capture.
> 
> - Justin