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

[Jacob Ritorto <jacob.ritorto%gmail.com@localhost>]

On Wed, Dec 4, 2019 at 5:41 PM Michael <macallan%netbsd.org@localhost> wrote:

> That's odd - machfb has no support for hotplugging monitors, I don't
> even know if the hardware can detect it. You may have moved the card
> while plugging in the monitor, that's the only reason I can think of
> for this to cause a crash.

I'm not able to reproduce it now, might've temporally correlated with
something else happening in the heat of battle.

> Machfb lives in src/sys/dev/pci/machfb.c
> options MACHFB_DEBUG in your kernel config will enable a bunch of debug
> output, including the EDID block.

Nice, will go there next, thx!

>
> > 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?
>
> The intention is to switch to the monitor's preferred mode - Sun OF has
> a nasty habit of sticking to VESA modes. We should really skip mode
> setting if what we want matches what the firmware set up for us though.

Any chance you could walk show me that logic?  I'm still spooling up
in my NetBSD efforts here and am just now figuring out this world's
version of loading sources and compiling kernels, etc.  But I do this
sort of stuff a lot - including way back to pdp11 2BSD and v7, etc, so
I can get there.  But a touch of hand holding could really accelerate
me if you have a sec..

>
> Since I'm working on a similar issue reported on port-macppc@ - any
> chance you can try a -current kernel?

Yeah, I *think* I did that (kinda guessing from general unix habits)
with the December 1 build of HEAD by slapping the new kernel down on
the root fs and telling boot to boot it instead of the default.  Was
that the right way?  Anyway, it crashed exactly the same way using
that HEAD kernel and method.

Related datapoint: I tried this same kernel supplanting test with
other kernel release versions down to 7.0.2 and that was the first one
that allowed normal boot to proceed without the crash.  7.1 crashes
just the same as 8.1 and HEAD (now 9).  So according to NetBSD release
dates webpage, the date gap there when it went from working to broken
is October 2016 to March 2017, so presumably whatever's triggering the
fault came in in that timeframe.  I've not yet figured out how PRs /
code changes correlate to releases, but working on it..


Generally, I'm eager to dive in here and answer whatever questions you
posit and have quite a few SPARCs and Macintoshes to help with real
hardware variety!

thx Michael!
jake

P.S. In minutes-old news, here, boot -c and disable machfb worked and
the machine booted okay using the generic fb.  It even shifted the
genfb0 resolution to 1280x1024 successfully with keyboard plugged in
and with screen/keyboard being used as wscons or whatever that's
called.  But X won't start with this genfb, so I'm still stuck.