[virglrenderer-devel] Some question about running a GLES backend for virgl

[Jakob Bornecrantz]

On 2018-03-22 01:38, Lepton Wu wrote:
> Hi Jakob,
> 
> I have seen you sent some CL to run virglrenderer with GLES backend.
> I am also interested in this and tried it and it doesn't work well for
> me. I have some questions:
> 
> 1.  The current virgl code is using some functions which is not
> available in GLES, for example, it's using glFramebufferTexture2DEXT
> and glBindBufferARB,  I can't find them in header files from GLES,
> then how it works with GLES backend?

Virgl is using libepoxy so it can use both GLES and desktop GL. We have 
added several checks to not call functions that are not available. 
Libepoxy will sometimes map a EXT function to a ARB function or a core 
function. If you are building virglrender make sure you have master of 
libepoxy.

It should all work as is, tho we have only tested on 3.2 and the many 
extensions that a Mesa driver gives. So there can be functions missing 
from angle.

> 
> 2. Any rough estimation for how long would it take for virgl work with
> a pure GLES backend?  basically I'd like to run virglrenderer on
> windows host and it seems it's easy to get GLES on windows with angle.
> So if virglrenderer can work with GLES backend, than perhaps it's not
> far away to get qemu+virgl works under windows.
We have it running now on Linux Mesa intel GLES 3.2 drier, if you are 
using the master branch of virgl.

What is not upstreamed right now is getting QEMU to give you a GLES 
context. Search and replace SDL_GL_CONTEXT_PROFILE_CORE with 
SDL_GL_CONTEXT_PROFILE_ES in ui/sdl2-gl.c in the QEMU source.

It should just work on Windows if you give virgl a GLES context, modulo 
different functions being available.

Cheers, Jakob.