Re: Framebuffers and VC setup (via fbcon.c)

[Jan-Benedict Glaw <jbglaw@lug-owl.de>]

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On Wed, 2004-03-10 18:15:57 +0000, James Simmons <jsimmons@infradead.org>
wrote in message <Pine.LNX.4.44.0403101806460.24760-100000@phoenix.infradead.org>:
> > 	- Despite the fact that (quite late in the boot process)
> > 	  vc_init() is called (with correct looking arguments), I think
> > 	  it should have been called quite some time earlier. With other
> > 	  (PC based) graphic cards, the machine just switches to FB mode
> > 	  after the FB driver is initialized. All further output is put
> > 	  there. But not here...
> > 
> > I haven't yet really understood how FB and console code work together,
> > so it would be nice to have some hints there :)

In the meantime, another VAX hacker (who initially worked on the 2.4.x
code base) hinted me: in the arch_setup function, I was missing a 

	conswitchp = &dummy_con;

After adding these, I got a penguin and a login prompt. However, the
console output (during further boot-up) didn't show up. But I'll get
there:)

>     I'm going to have to look at your driver. Normally one of two things 
> happen. Some driver have there hardware modes set by firmware and they 
> can't be changed. For example VESA fbdev. In this case you lack a 
> xxxfb_check_var and xxxfb_set_par function. Then fbcon doesn't attempt to 
> change the hardware state but use the current one. 
>   The other case is that your driver sets the hardware state. You have a 
> set_check_var and a set_par function hook in struct fb_info->fbops. So the 
> fbcon layer will call set_par directly for you.

Well, as I know today, there are more variants of this hardware, some of
them capable of changing screen resolution. So I think I'd add those two
functions (after I figured out how to actually change modes, or even how
to properly detect the available hardware at all:)

Thanks for these valuable hints! Oh, just another question: the largest
of theses framebuffer devices can handle four CRTs. Just need to
register four framebuffers, then?

After all, I've had my very first local login last night, at 00:42:23
CET with local monitor and keyboard on a VAX. Right, I waited some
seconds to get that nice time on my watch:)

MfG, JBG

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