[Mesa-dev] [PATCH 0/2] Disable the EGL state tracker for Linux/DRI builds

[Jose Fonseca]

> How many people/companies use EGL for Windows/fbdev, how about OpenVG on
any platform ?

I already said this privately to Marek when he was RFC'ing on this change: I'm fine if Linux-specific drivers abandon st/egl to focus solely on st/dri, but removing st/egl altogether seems unnecessary and short-sighted: EGL is a cross-platform API, Mesa is a cross-platform implementation of OpenGL and friends, so sooner or later people will want to have Mesa's EGL support on platforms others than Linux.

This is not hypothetical:
- See https://bugs.freedesktop.org/show_bug.cgi?id=40920 for an example of a bug reported from an user using llvmpipe + egl + opengv on windows.
- VMware doesn't currently ship or support EGL on Windows, but I suspect we eventually we'll want to support EGL on non-linux platforms.

Even if OpenVG is loosing popularity, but maybe Khronos will come up with another cross-platform graphics API (maybe OpenGL NG) that's tied to EGL.

So a cross-platform implementation of EGL is bound to be useful.


I don't test, but I build egl-static and OpenVG on Windows nightly w/ llvmpipe.  It's like a superset of OSMesa, and it seems more useful, as it gives one more APIs than OSMesa, and through a standard API to create/bind contexts .


In short, stop caring about st/egl on Linux, maybe even remove DRI support out st/egl if you must, but please don't go out of your way to break EGL on non-linux platforms.


Jose

________________________________________
From: mesa-dev <mesa-dev-bounces at lists.freedesktop.org> on behalf of Emil Velikov <emil.l.velikov at gmail.com>
Sent: 05 November 2014 00:46
To: Marek Olšák; mesa-dev at lists.freedesktop.org
Cc: emil.l.velikov at gmail.com
Subject: Re: [Mesa-dev] [PATCH 0/2] Disable the EGL state tracker for Linux/DRI builds

On 04/11/14 22:42, Marek Olšák wrote:
> Hi everybody,
>
> I'm about to address this long-standing issue: The EGL state tracker is
> redundant. It duplicates what st/dri does and it also duplicates what
> the common loader egl_dri2 does, which is used by all classic drivers
> and even works better with gallium drivers.
>
> Let's compare EGL extensions for both backends:
>
> st/egl:
> EGL version string: 1.4 (Gallium)
> EGL client APIs: OpenGL OpenGL_ES OpenGL_ES2 OpenVG
> EGL extensions string:
>     EGL_WL_bind_wayland_display EGL_KHR_image_base EGL_KHR_image_pixmap
>     EGL_KHR_image EGL_KHR_reusable_sync EGL_KHR_fence_sync
>     EGL_KHR_surfaceless_context EGL_NOK_swap_region
>     EGL_NV_post_sub_buffer
>
> egl_dri2:
> EGL version string: 1.4 (DRI2)
> EGL client APIs: OpenGL OpenGL_ES OpenGL_ES2 OpenGL_ES3
> EGL extensions string:
>     EGL_MESA_drm_image EGL_MESA_configless_context EGL_KHR_image_base
>     EGL_KHR_image_pixmap EGL_KHR_image EGL_KHR_gl_texture_2D_image
>     EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image
>     EGL_KHR_surfaceless_context EGL_KHR_create_context
>     EGL_NOK_swap_region EGL_NOK_texture_from_pixmap
>     EGL_CHROMIUM_sync_control EGL_EXT_image_dma_buf_import
>     EGL_NV_post_sub_buffer
>
> egl_dri2 also supports MSAA on the window framebuffer (through st/dri).
> It's really obvious which one is better.
>
> I'm aware of 2 features that we will lose:
> - swrast on Wayland - I'm not sure about this. Perhaps kms-swrast has
> addressed this already.
> - OpenVG - It has never taken off. If people want this on Linux, it should
> use egl_dri2 and st/dri, like OpenGL does.
>
> This series removes st/egl and st/gbm support from the autoconf build
> (the latter depends on the former and is probably just as redundant).
> The next step is to remove all Linux-specific backends from st/egl.
> Windows, Android, and other platform backends will be kept intact,
> therefore st/egl won't be removed completely.
>
> Please comment.
>
A few thoughts:
 - Iirc Eric is using st/egl as the dri2 backend seems to be causing
problems :(
 - Android supports dri modules, but st/dri/Android.mk is missing.
Should be trivial to add.
 - Windows - might be a pain in the a** to get it working. Then again
does Windows have EGL ?
 - fbdev, OpenVG - the etnaviv project was using the former, currently
moving to full-blown drm :)

If one is to nuking the three st we can remove
 - the libEGL symbol export mayhem
 - gallium's st_api, and flatten things a bit
 - a bit of duplication :)

In summary:
With a bit of work we can remove Linux and Android from the equation.
How many people/companies use EGL for Windows/fbdev, how about OpenVG on
any platform ?

Cheers,
Emil

> Thanks,
>
> Marek
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