Re: conflicts between fbcon and user-mode fbdev clients

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"