Intel Is Getting Very Close With Its Last Extension For OpenGL 4.3

[phoronix]

Phoronix: Intel Is Getting Very Close With Its Last Extension For OpenGL 4.3

For Broadwell hardware and newer, this week marked the milestone of the Intel Mesa driver exposing OpenGL 4.2 support. However, they are only one extension away from OpenGL 4.3 compliance for the newer Intel graphics hardware and a new version of that patch-set was just posted...

http://www.phoronix.com/scan.php?page=news_item&px=Intel-GL43-Buffer-Access-V2

[ids1024]

Is there any chance that some of this work will benefit my Ivy Bridge processor?

Either way, it is good to see the Intel driver making such progress.

[FireBurn]

Wothout the SIMD32 work compute shaders aren't exposed on Slylake, and GL4.3 can't be exposed

[cj.wijtmans]

Wothout the SIMD32 work compute shaders aren't exposed on Slylake, and GL4.3 can't be exposed

is Slylake a new chipset?

[Ericg]

is Slylake a new chipset?

Skylake is newest CPU architecture, yes.

[Gusar]

Is there any chance that some of this work will benefit my Ivy Bridge processor?

Nope, the pachset as posted is for BYT (Baytrail) and HSW+. Which is kinda weird, as Baytrail and Ivy Bridge are both gen7 GPUs.

Then there's another piece of the puzzle missing for Ivy (and Haswell too, for that matter) to get OpenGL 4.3 - stencil texturing. I searched the mesa list and found stencil texturing patches for gen6/7 posted two years ago, but nothing became of that. For any Intel devs reading this - any plans to resurrect that work and provide stencil texturing for gen7 at least?

Also robust_buffer_access is the second extension recently that's HSW+ (the other being query_buffer_object), what happened to Ivy? Aren't Ivy and HSW similar enough to both get support?

[Kayden]

Nope, the pachset as posted is for BYT (Baytrail) and HSW+. Which is kinda weird, as Baytrail and Ivy Bridge are both gen7 GPUs.

Yeah...both Baytrail and Haswell gained native support for 3-element vertex formats, while Ivybridge (as the older Gen7) doesn't support them and has to fall back to 4-element vertex formats. I'm not yet sure if that's essential, but that's why it is how it is.

Then there's another piece of the puzzle missing for Ivy (and Haswell too, for that matter) to get OpenGL 4.3 - stencil texturing. I searched the mesa list and found stencil texturing patches for gen6/7 posted two years ago, but nothing became of that. For any Intel devs reading this - any plans to resurrect that work and provide stencil texturing for gen7 at least?

Yes, definitely. It's required for ES 3.1, and we plan to support that on Gen7. Thanks for reminding me about those old patches!

Also robust_buffer_access is the second extension recently that's HSW+ (the other being query_buffer_object), what happened to Ivy? Aren't Ivy and HSW similar enough to both get support?

Sadly, not always. The point of ARB_query_buffer_object is to be able to produce query results without stalling and synchronizing with the CPU. On Haswell, the GPU gained a new "command streamer math" feature which allows us to do simple arithmetic on counters in a pipelined fashion (read a starting/ending counter snapshot, subtract the two, multiply by 4, and so on). This lets us easily do everything we need on the GPU. Ivybridge and Baytrail don't have that. We /could/ do it by using a compute shader, or a vertex shader rendering a single point with transform feedback, but that requires re-programming the entire pipeline, which seems pretty complex and heavyweight. I suppose we could also just stall and use the CPU, but that seems rather unfortunate as well. So for now, it's Haswell+ only.

[GreatEmerald]

Skylake is newest CPU architecture, yes.

Slylake, not Skylake

[JMB9]

AFAICS concerning OpenGL, OpenCL and Vulkan:
x Ivy Bridge [Gen7] should support OpenGL 4.0, OpenCL 1.2 and Vulkan 1.0,
x Haswell [Gen7.5] supports even OpenGL 4.3,
x Broadwell [Gen8] supports OpenGL 4.4 and OpenCL 2.0,
x Skylake [Gen9] same OpenGL and OpenCL level.
[ see https://en.wikipedia.org/wiki/Intel_..._Iris_Graphics ]

So restricting to Broadwell (or even Skylake) may be easier and thus
acceptable as first step (as was reported), but it would be nice to hear
when / if:
- Ivy Bridge (and all later chipsets) gets OpenGL 4.0 and Vulkan 1.0 support,
- Haswell OpenGL 4.3 and Vulkan 1.0 support (both not available next Mesa release - right?),
- and if Skylake can support OpenGL 4.5 - this was said in the proposal to hold back
Mesa release - but seems to contradict to above given article citing Intel resources.

I am working at a Haswell system with 4k screen right now - so I am personally
involved and try to get these pieces of information.
Hearing of Broadwell gains and Haswell stagnation is thus not welcome.
So I really do hope that will change in time for fall distribution releases
(Xubuntu 16.10 and others ...).

And as someone remarked in an earlier Intel graphics comment:
Intel should feel obliged to deliver (or help with development of) Linux drivers
for that exact level they advertised their chips with.

Maybe there is an Intel website with that information already ... ?
Would be welcome to get such an URL.
Or someone with inside information and permission to talk about could make a comment?

P.S.: IRC may not be such a good way to help spread pieces of information - I would
prefer an official website or blog. Similar to this topic of LWN May 5, 2016 citation:
~
Answering a user question on IRC doesn't scale, only one person and a few
lurkers will benefit from it. Answering a user question on a mailing list
scales a little better, since the answer is archived and can be searched for.
What really scales is instead to improve the reference manual.
Yes, you know, documentation.
-- Sébastien Wilmet

[smitty3268]

AFAICS concerning OpenGL, OpenCL and Vulkan:
x Ivy Bridge [Gen7] should support OpenGL 4.0, OpenCL 1.2 and Vulkan 1.0,
x Haswell [Gen7.5] supports even OpenGL 4.3,
x Broadwell [Gen8] supports OpenGL 4.4 and OpenCL 2.0,
x Skylake [Gen9] same OpenGL and OpenCL level.
[ see https://en.wikipedia.org/wiki/Intel_..._Iris_Graphics ]

That's just listing what GL version the windows driver exposes, not what the hardware is actually capable of. The Intel Windows drivers have long focused heavily on DX support rather than GL, so it's not exactly surprising that they don't max out the hardware capabilities.

I'm pretty confident Haswell, Broadwell, and Skylake can all reach GL 4.5 without any trouble. I'm not sure about Ivy Bridge, but I'd expect it could support at least 4.2 and i think probably the full 4.5 as well. The older generations will just need some more work to get there than the newer ones do.

Sandybridge (gen 6) is where i think actual hardware limitations start limiting support.