> > > > The fb_ops can only be called from fbcon or the fbdev userland
> > > > interface.
> > > > The fbcon calls should only happen when the VC is in KD_TEXT mode. Now
> > > > with the DRM backend we have the advantage of creating a mapping
> > > > seperate
> > > > from the console mapping. A fb_open/fb_close could be used to cleaning
> > > > up
> > > > the userland mmap as well as handle the console pinning. We can supply
> > > > your own fb_mmap hook.
> > >
> > > Again, the issue is not userspace but that fb_ops hooks can be called
> > > from interrupt context etc.
> >
> > This should not happen. The VT layer is protected from calling in the
> > interrupt context. TNor does fbcon call any fb_ops methods from a irq.
>
> E.g. printk?
Sorry I have been sick. This is true when you are in KD_TEXT mode and using
fbcon.
Now while working on a graphical console yes you can have other hardware
devices do
a printk which can alter the state of of your graphics card. As for debugging a
graphics driver you have to be very careful with your printks. Usually in that
case
I use two graphics cards in my system and map one to fbcon and test the other
graphcis cards driver.
P.S
The fbdev api is such that it doesn't always require a permanent
framebuffer
mapping. This was done for the case of graphical hardware that lacks a directly
accessable framebuffer. If you have accelerated fillrect,copyarea,and imageblit
then
you don't even the mapping except in the case of someone calling mmap on
/dev/fbX.
I noticed the nouveau drivers has a accelerated fbcon :-)
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