Re: [Linux-fbdev-devel] [PATCH] FBDev: vga16fb port

[James Simmons]

> If X is running  in native mode then it has to save the register state. 
> Otherwise you cannot switch to a console.  If X is running on top of
> fbdev, then state restore/saves are done using fb_set_var and
> fb_get_var.  The registers are not touched, that's the purpose of fbdev.
> 
> If you are running vgacon, fbdev, and native X, then yes, fbdev and X
> has to do a save of their initial state.

Not really. When X closes /dev/fb then fb_release is called which if the 
driver supports it will switch back to text mode. The exception is 
firmware based fbdev drivers like vesafb and offb.  

> > Does this also apply to vesafb ?
> Not too sure about this. vesa requires real-mode initialization.  Either
> you do this at boot time, or fake a real-mode environment like what X
> does.

X has to reset the vidoe hardware back to the state that matches what the 
VESA mode was. Other wise it will mess you your system.

P.S

    X on VESA fb always foobars my system when I exit X.