SUMMARY: Screenblank problem

From: Brian T. Wightman (
Date: Tue May 21 1996 - 23:54:10 CDT

Thanks to James Hsieh for replacing the light bulb :)

The problem was that in the process of trimming drivers to free up
limited real estate, I had removed the bwtwo driver from the kernel.
Since this is the only B&W machine, it never clicked. See below for


Brian T. Wightman
Academic Computing, UW Oshkosh wightman@oshkoshw.bitnet
800 Algoma Blvd, Dempsey Hall 307
Oshkosh, Wisconsin 54901 Phone: (414) 424-3020

In message <9605220013.AA15828@soemail>,
  James Hsieh wrote:
> --------
> Hi Brian,
> > Environment:
> > SPARCstation IPC, 8MB memory (don't laugh :)
> > B&W monitor using on-board video card (/dev/bwtwo0)
> > SunOS4.1.3 w/ current patches (I think :)
> I'm not -- I used to have one. :-)
> (Apologies in advance if I sound a little disoriented or bizarre -- I've
> spent the day setting up a whole lab of Ultra systems and think I've been
> exposed to just a little too much radiation... ;-) )
> > Possible clue:
> > On startup I get a message that there is
> > "No default frame buffer found". This message is issued
> > right before /etc/rc.boot executes.
> >
> > Anyone have any ideas? Not an urgent matter, just an annoyance that
> > has been sitting on my work queue for a while.
> Yes. Obviously, you've never tried to run a windowing system on this system
> before, because with this message, it wouldn't have worked (or rather, it
> shouldn't have worked). No other framebuffers, right? Console-mode only,
> right?
> If all true, then offhand, it sounds like your kernel got stripped down at
> some point and someone removed the bwtwo support for your kernel. You can
> run fine without the device driver support in the kernel if you're just using
> the framebuffer for console mode because console mode is handled by the OBP
> via FORTH code built-into the bwtwo's PROM. If you want more gory details as
> to what this process is all about, send me e-mail and I'll give you the
> Reader's Digest lowdown...
> screenblank tries to open /dev/fb. Without the device driver support in the
> kernel, you would not have /dev/fb mapped to anything, so screenblank just
> exits. If the device driver were in your kernel, /dev/fb would get mapped
> to the bwtwo and screenblank would work hunky-dory'ish.
> Go to /usr/share/sys/sun4c/conf and look at the configuration file for your
> kernel and see if bwtwo is commented out. If it is, put it back in, rebuild
> your kernel, install your kernel, and reboot. That part is left as an exerci
> se
> to the user (though I can probably still give you instructions on how to do
> it even though I haven't had to do it in about 2 years).
> Hope that this gives you some ideas on where to look!
> Regards,
> --James
> --
> [ James Hsieh (stickman) O Systems Programmer ]
> [ UC San Diego School of Engineering --+-- Ofc of Engineering Computing ]
> [ 9500 Gilman Dr 0405 | email: ]
> [ La Jolla, CA 92093-0405 / \ URL: ]

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