Re: [Linux-fbdev-devel] Some questions

[Michel <mi...@da...>]

On Mit, 2003-03-12 at 09:24, Geert Uytterhoeven wrote:
> On 12 Mar 2003, Michel [ISO-8859-1] Dänzer wrote:
> > On Mit, 2003-03-12 at 02:02, Antonino Daplas wrote:
> > > On Wed, 2003-03-12 at 08:07, Michel Dänzer wrote:
> > > > On Die, 2003-03-11 at 23:51, Antonino Daplas wrote:
> > > > > On Wed, 2003-03-12 at 06:23, Thomas Winischhofer wrote:
> > > > > > > 
> > > > > > > I actually prefer #3, and I already have working code for this.  We can
> > > > > > > also make this driver switchable (ie, drivers that are not affected by X
> > > > > > > can disable this, and only drivers that are affected such as the riva,
> > > > > > > aty, radeon, etc can turn this on).
> > > > > > 
> > > > > > What exactly is a "trusted" console?
> > > > > 
> > > > > By default, the pid of each vt is -1.  When X loads, it installs its own
> > > > > VT (ie vt7), which in that case the pid of that particular vt == X's
> > > > > pid.  We can check this pid, and if switching from a vt with pid == -1,
> > > > > we can safely assume that the hardware state is still sane, and if not,
> > > > > assume the hardware state is undefined.
> > > > 
> > > > Can you also detect when the app has opened the framebuffer device, and
> > > > assume it's playing nice when it has? (for Option "UseFBDev")
> > > 
> > > X using fbdev will also have the same limitation. I have implemented
> > > something like this before.  For each fb_open, the current->pid can be
> > > saved into a "white list" and removed for each fb_close.  fbcon can then
> > > compare this to the pid of the vt it's switching from.
> 
> The application cannot play not nice unless it mmap()s the MMIO registers. To
> be able to do that, it first has to clear FB_ACCELF_TEXT in var.accel_flags.

X will map the MMIO registers with Option "UseFBDev" and still play nice
(hopefully :).

> > > This is becoming to sound very ugly though.  I guess, the best way is to
> > > really support Option "UseFBDev", or at least have the user decide if
> > > he/she wants to have the hardware refreshed.  
> > 
> > I'm afraid I don't understand what you're saying here.
> 
> But I think you do agree :-) He says that if fbdev is active, the X server has
> to be fbdev compliant and thus not mess with the hardware where it's not
> allowed to.

I agree that's how it should be.


-- 
Earthling Michel Dänzer (MrCooper)/ Debian GNU/Linux (powerpc) developer
XFree86 and DRI project member   /  CS student, Free Software enthusiast