EGL_MESA_choose_display version 1

[Jon Smirl]

On 6/14/05, Adam Jackson <ajax at nwnk.net> wrote:
> On Monday 13 June 2005 23:00, Jon Smirl wrote:
> > I've been using fbdev devices names - fb0,  fb1, etc. Linux has udev
> > for assigning a specific device name to correspond to a specific
> > card/PCI slot. From the fbdev device name I can figure out which chip
> > specific driver to load.
> >
> > I may switch this to use the DRI device names - card0, card1, etc.
> > Again correspondence to the PCI slot is controlled by udev.
> 
> I'm not a huge fan of embedding the name under /dev into the display
> specification.  I could probably be convinced that a 'display/0' scheme makes
> sense and explicitly allow that to have implementation-defined ordering, but
> that's about it.  Remember this isn't really intended to be a user-visible
> string, this is just how the server selects displays from the EGL stack.

If you start Xegl without any parameters it will look at /dev/dri and
see which devices it has permission to open and then open all of the
ones it can. Doing that relies on a PAM module to assign the dev
ownership to the logged in user.

I'm looking at a future model where where there is one DRM/fb device
per screen. fb is currently one per screen and DRM is one per card.
I'll modify DRM to expose one per screen (these will all be pointing
to the current DRM code there will just be multiple names). By having
one fb/DRM device pair per screen we are opening up a path for having
two independent user logged onto the two devices. We need two DRM
device nodes since they will have different ownership permissions.

There is no problem taking the list of card0,card1,etc and converting
it to display/0, display/1,etc and then back again in the driver. But
I do need these to represent screens not devices. Display is ambiguous
as to whether it is a screen or device. Would screen/0, screen/1 be
better?

-- 
Jon Smirl
jonsmirl at gmail.com