[Mesa-dev] [RFC] New EGL extension: EGL_EXT_platform_display

Chad Versace chad.versace at linux.intel.com
Tue Feb 26 12:53:49 PST 2013

On 02/25/2013 11:58 PM, Pekka Paalanen wrote:
> On Mon, 25 Feb 2013 09:09:22 -0800
> Chad Versace <chad.versace at linux.intel.com> wrote:

> Thank you for the reply. Indeed, that dance to check for the extension
> is non-trivial, and I think it might be good to explain somehow in the
> spec, maybe in the Q&A section?

Yes, I'll add the topic to the Issues section.

> I quickly checked the EGL 1.4 spec, and could not spot any mention of
> whether eglGetProcAddress needs a valid context or display or anything.
> Does it require any initialization? Well, should not matter much I
> guess, since in any case you have to open a display first to get the
> extensions string.
> Btw. what is EGL_DEFAULT_DISPLAY in Mesa, what does it give us?

Ah, that is complicated. In the Mesa configuration that nearly everyone
uses, eglGetDisplay(EGL_DEFAULT_DISPLAY) calls XOpenDisplay(NULL) to acquire
the display. If Mesa is configured as Wayland-centric, though,
then eglGetDisplay(EGL_DEFAULT_DISPLAY) calls wayland_display_connect(NULL)
to acquire the display. It's also possible to select to which platform
EGL_DEFAULT_DISPLAY belongs with the env var EGL_PLATFORM, but, according
to Kristian, that method is deprecated.

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