Re: conflicts between fbcon and user-mode fbdev clients

[James Simmons <jsimmons@infradead.org>]

> Hi fbdevs,
> 
> This is probably a FAQ, but I haven't found the answer.
> 
> What (if anything) should a driver be doing to prevent fbcon and other
> clients (e.g. X, etc.) from simultaneously opening and rendering to
> the framebuffer?
> 
> Running a USB graphics device using the udlfb framebuffer driver
> (in the staging tree of 2.6.32), a common problem is fbcon
> automatically opens the first available framebuffer device (/dev/fb0).
>  Then when the user loads an X server, both the X server and fbcon
> continue to merrily render to the device, overwriting each other.
> 
> So, typically, the udlfb driver will see this sequence at boot (with
> the xf-video-displaylink X server):
> fb_open(user = 0)  fbcon opening the framebuffer
> fb_open(user = 1)  X opening the framebuffer
> fb_open(user = 1)  Another instance of X opening framebuffer
> * X and fbcon both render to the framebuffer, causing a mess *
> And then any calls to release() later.

That shouldn't happen. In the xorg.conf do you have in the 

Option UseFBDev "True"