I've started playing with the modesetting branch of DRM and managed to get it 
to work on my GMA 965 based laptop (after working out I needed to pass 
modeset=1 as a parameter to the i915 module).

On my laptop, I get /dev/fb0 & /dev/fb1, with /dev/fb0 connected to my laptop 
screen (LVDS?) and fb1 connected to VGA out. I can successfully run 
Qt/Embedded on fb1 (using the normal fbdev interface... not started writing 
drm modesetting code yet).

What would be nice is to have a tool like fbset which not only sets the mode, 
but also chooses which crtc (correct terminology?) is connected to which 
framebuffer. On the OMAP framebuffer, this can be controlled through a sysfs 
interface.

However, my understanding is that the i915 driver provides a linuxfb emulation 
driver it registers with the kernel during probe? The fbcon then binds to the 
(first) fbdev device? So the tool would in fact just configure i915's linuxfb 
emulation and not be very useful or portable. Have I understood things 
correctly?

I'm getting a bit confused about how things should look inside the kernel 
(This is mainly because I'm having a hard time working out how consoles, 
virtual terminals & vt-switching fit together... but I'm picking it up 
bit-by-bit). It seems to me that a completely new console driver needs to be 
written which uses the drm modesetting interface, rather than the fbdev 
interface? So the tool to set modes & change crtcs would only talk to the 
console driver. 

User-space applications like X & Qt/Embedded seem pretty strait-forward. They 
just use mode setting functions in libdrm. I.e. They provide their own way of 
configuring which output goes to which crtc. What about vt-switches? Will an 
application still be responsible for re-drawing itself after a vt-switch? Or 
will vt-switches now become completely transparent to userspace applications?


Please let me know what I've got wrong. Eventually, I'd quite like to have a 
go at writing some in-kernel stuff using the drm. If there's any boring 
low-hanging fruit I could start to learn on, let me know (like an fbset-like 
utility).


Cheers,

Tom

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