[Mesa-dev] ARB_transform_feedback[23] on Haswell, Ubuntu 14.04

[Matt Turner]

On Thu, Jan 15, 2015 at 4:08 PM, Brian Paul <brianp at vmware.com> wrote:
>
> I have a question on behalf of a coworker.  He's using Ubuntu 14.04 (Mesa
> 10.1.3, kernel 3.13.0) on a Haswell system.  But glxinfo does not list
> support for GL_ARB_transform_feedback[23].  It does list
> ARB_conservative_depth.
>
> According to the driver code (from master, 10.1.3 lacks ARB_texture_view):
>
>    if (brw->gen >= 7) {
>       ctx->Extensions.ARB_conservative_depth = true;
>       ctx->Extensions.ARB_texture_view = true;
>       if (can_do_pipelined_register_writes(brw)) {
>          ctx->Extensions.ARB_transform_feedback2 = true;
>          ctx->Extensions.ARB_transform_feedback3 = true;
>          ctx->Extensions.ARB_transform_feedback_instanced = true;
>          ctx->Extensions.ARB_draw_indirect = true;
>       }
>
> this seems to indicate that can_do_pipelined_register_writes() is failing.
> The comments on that function say it can fail if the kernel driver isn't new
> enough.  So I'm guessing this is a kernel module issue.
>
> Can anyone confirm this behavior with Ubuntu 14.04?

Yes, that's expected, unfortunately.

We've been waiting on the kernel for like two years now to let us do
register writes. I hear it'll be ready Real Soon Now.