Subject: Re: wsdisplay, early consoles etc.
To: Michael Lorenz <email@example.com>
From: Eduardo Horvath <eeh@NetBSD.org>
Date: 11/06/2006 16:27:08
On Sat, 4 Nov 2006, Michael Lorenz wrote:
> On Oct 26, 2006, at 13:36, Michael Lorenz wrote:
> > I'd like to make the following addition to wsdisplay.c - a version of
> > wsdisplay_cnattach() that can be overridden exactly once. The reason to do
> > that is this - macppc has been hardcoded to use ofb as console for ages but
> > we do have a few accelerated framebuffer drivers now ( like machfb,
> > voodoofb, radeonfb, chipsfb ) which all work on macppc. The problem is that
> > macppc relies on having a rasops-based console more or less from kernel
> > startup.
> > In my opinion it would be a good idea to have a generic framebuffer console
> > attach as early as possible and later allow some hardware-specific driver to
> > override it. This would nicely solve several headaches - we wouldn't have to
> > decide which driver to attach on startup before autoconf. Specific drivers
> > wouldn't have to implement xxx_cnattach() methods. And drivers would be
> > plug-compatible between at least sparc64 and macppc ( sparc64 uses OF output
> > until a driver takes over ).
> > The same could be useful on i386 and the like as well - cnattach vga for
> > early startup, then - maybe - let a framebuffer driver take over for an
> > accelerated high-resolution console.
> > I have these changes in my local source tree for ages now, they seem to be
> > unproblematic.
> > Besides that - we should come up with a generic interface to let a driver
> > find out if it's supposed to become the system console or not. On
> > OpenFirmware machines that's easy - just check /choosen/stdout - but it's
> > ugly to have OF-dependencies in drivers that reside in sys/dev/pci. Maybe we
> > should just have the MD autoconf code attach properties for:
> > - - console
> > - - display mode
> > - - font
> > - - whatever I can't think of right now
> I guess no protest means no objections?
Does wscons support split intput and output devices yet? If not, you
should look into that. Being able to use a serial port for input and
framebuffer for output or keyboard for input and serial port for output is
invaluable for debugging.