Intel Mesa Driver Lands Support For OpenGL ARB_shader_ballot

[phoronix]

Phoronix: Intel Mesa Driver Lands Support For OpenGL ARB_shader_ballot

Just in time for this weekend's expected Mesa 17.2 branching, the Intel "i965" Mesa driver has landed support for the ARB_shader_ballot OpenGL extension...

http://www.phoronix.com/scan.php?page=news_item&px=Intel-Mesa-Lands-Shader-Ballot

[plonoma]

Good work from the Intel developers.
But the Intel driver is still running behind on implementing the GL_ARB_indirect_parameters extension.
The radeonsi (AMD) and nvc0 (Nvidia) drivers have already implemented this extension a long time ago.

[Linuxxx]

I assume both "Gen7" & "Gen7.5" (IvyBridge & Haswell, respectively) could also support this extension, but Intel doesn't seem to implement any of the post OpenGL 4.5 features for those chips anymore...
Makes me wonder if at least Haswell could get OpenGL 4.6...
Kayden ???

[Kayden]

I assume both "Gen7" & "Gen7.5" (IvyBridge & Haswell, respectively) could also support this extension, but Intel doesn't seem to implement any of the post OpenGL 4.5 features for those chips anymore...Kayden ???

Actually, it looks like Matt enabled GL_ARB_shader_group_vote all the way back to Gen4.

The reason you've seen a bunch of new features go by without Haswell support is because most of them require new hardware support - the older GPUs can't do them. Looking at a list of GL extensions we don't support on Haswell:

• GL_ARB_shader_stencil_export
• GL_KHR_blend_equation_advanced_coherent
• GL_KHR_texture_compression_astc_ldr
• GL_KHR_texture_compression_astc_sliced_3d
• GL_INTEL_conservative_rasterization
• GL_ARB_post_depth_coverage

All of the above require new hardware support that was introduced on Skylake (Gen9+): the ability to write arbitrary stencil from the fragment shader, coherent framebuffer read messages, ASTC, and some rasterizer bits. (Technically, ASTC could be done on Cherryview/Braswell too...there are a couple bugs we'd have to work around. But Haswell can't.)

• GL_ARB_gpu_shader_int64

Haswell doesn't do 64-bit integers natively, so we'd have to emulate it. I suppose we could, but I haven't heard much demand for this feature...

• GL_ARB_shader_ballot

This requires GL_ARB_gpu_shader_int64...so we'd have to do that first.

• GL_ARB_ES3_2_compatibility

This probably could be exposed on Haswell (since it doesn't require ASTC). Not sure why I didn't. I haven't heard of any apps using it.

So, while it might seem like we're neglecting Haswell, we're actually still taking it as far as it can (and further than Windows). I know I haven't abandoned it yet.

[Gusar]

So, while it might seem like we're neglecting Haswell, we're actually still taking it as far as it can (and further than Windows). I know I haven't abandoned it yet.

Yeah, seeing better support on Linux than there is on Windows is quite cool. You've pretty much squeezed everything possible out of this old thing now (save for emulating int64 ). As a Haswell owner I thank you for that.

But I also own a Baytrail machine, so, are Ivy/Baytrail still in consideration? Stencil texturing would bring those two up to GL 4.3 and ES 3.1, which would be cool.

[Kayden]

But I also own a Baytrail machine, so, are Ivy/Baytrail still in consideration? Stencil texturing would bring those two up to GL 4.3 and ES 3.1, which would be cool.

We're actually doing a lot of optimizations that should benefit Baytrail (and Braswell, and Apollolake) right now. Feature-wise...the only thing stopping stencil texturing and ES 3.1 is fixing up bugs with integer textures and GL_CLAMP_TO_BORDER. I've already written a lot of the code, but haven't found time to finish it off yet. I'd like to see it happen, but I don't know when I'll ever have time..

Ivybridge/Baytrail are pretty much the cut-off at this point. Nobody really wants to work on earlier platforms anymore (though we do sometimes). The newer hardware is so much faster and more capable...

[suberimakuri]

Thanks Kayden , really imformative, appreciate the support.