Query regarding initial mode setting by X server & /dev/dri/control

[Akash Hajari]

Hi Rob,

Thanks for your answer and your example
(https://github.com/robclark/kmscube/blob/master/kmscube.c). I
understood standalone KMS without x11 (as written by you @
http://lists.freedesktop.org/archives/dri-devel/2012-September/027348.html
).

But, looking at Linux Graphics stack
(http://en.wikipedia.org/wiki/File:Linux_Graphics_Stack_2013.svg), I
am confused. Does libGL calls always directly calls libDRM and never
to x-server?

If so, then how simple gl example ‘drawf.c’
(http://www.glprogramming.com/red/chapter08.html) using glBitmap()
work well when x11 server running?


Also, when switching between multiple windows, x server running in
backgroung, why drm_mode_addfb (DRM_IOCTL_MODE_ADDFB) getting called
many times?
(as I think, fb might have already created for multiple windows.)

Thanks for your patience, Rob.

Akash Hajari.

On 1/14/14, Rob Clark <robdclark at gmail.com> wrote:
> On Tue, Jan 14, 2014 at 5:15 AM, Akash Hajari <akashhajari at gmail.com>
> wrote:
>> Hi,
>> I am new to DRM & KMS and I had seen your pdf named "why & how to use kms
>> as
>> your user space display api if choice".
>> I have to understand initial mode setting  flow of x server. So is it
>> located in /xorg-server/hw/xfree86/modes/ or some where else?
>
>
> currently it is in each different DDX driver (for example,
> xf86-video-intel, xf86-video-modesetting, etc)
>
> Perhaps either tests/modetest/modetest.c (in libdrm tree) or kmscube
> (https://github.com/robclark/kmscube/blob/master/kmscube.c) might be a
> simpler stand-alone example to look at (the former does only modeset,
> the later does modeset + gl)
>
>> And, I don't know use control node. What's use of /dev/dri/control node?
>
> I don't think it is really used for much yet.. but mostly people just
> use drmOpen() in libdrm and it figures out what device file to open.
>
> BR,
> -R
>
>>
>> Akash Hajari.
>>
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>>
>