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Re: NetBSD 8.1 / Sun Ultra5 install crash during initial kernel device autosizing

First, huge thanks for such fast and useful responses.  Especially to
a first-timer here.

My intention is to help troubleshoot this and to alleviate the trouble
surrounding graphics modes -- possibly decrease brittleness
surrounding displays and support more monitors (or at least not
blatantly crash on mismatch) if that's really what's going on..

I've noticed that on boot, my other SPARC NetBSD machines change video
modes and load new fonts, overriding the default OBP ones.  This
extravagance is not lost on me personally -- warm, modern and very
pleasant indeed, but in retrospect feels kind of related to this

I've since my initial post gathered up serial console plumbing and
have gone through headless boot (and successful 8.1 install!) .  Works
fine, no crashes.  One really interesting thing was that after
install, when I tried Michael's advice and plugged in a different
monitor (while running), the system panicked! Just from changing
displays.  I suspect this behaviour isn't the intent, but nonetheless
opens up the possibility of troubleshooting this issue more deeply
since we might potentially instrument the EDID, failure mode, etc.
from the perspective of a stable running system.

The last boot message I can grab when booting with head and using my
eyes is something about post_div, which I suspect comes right after
the machfb stuff.  Planning to review other boot messages and try to
interpret what that means.  But in the meantime, does anyone know of a
way to let me instrument the machfb piece?  Like, where's that in the
source tree?  Sorry for the newbie question -- new here.  Can I change
and rebuild machfb and stuff it into the kernel to provide some
tracers and see EDID, etc? I'd like to sanity-check my EDID info
coming in and ascertain whether the existing code digests it.

Another question (and forgive me if this is contentious -- again, new
here) is: while I do enjoy the more snazzy font and resolution switch
at boot on my other spares that work well,  why is the video mode
changed at boot?  For aesthetics?  If so, wouldn't it be less fragile
and more accommodating to leave it at default?

Open to any input, critique, direction, etc. and thanks in advance.

On Tue, Dec 3, 2019 at 7:46 PM Mike Barnes <mike%bremensaki.com@localhost> wrote:
> > Do you have a different monitor to try? This looks like machfb tries to
> > program a video mode and for some reason screws up. My initial thought
> > is that maybe the monitor's EDID block describes a mode machfb can't
> > support for whatever reason.
> I'm using a Sun LSA800 flat panel monitor with mine, same results.

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