[Nouveau] Fermi+ shader header docs

[Ilia Mirkin]

On Thu, May 21, 2015 at 10:05 AM, Robert Morell <rmorell at nvidia.com> wrote:
> Hi Ilia,
>
> On Sat, May 02, 2015 at 12:34:21PM -0400, Ilia Mirkin wrote:
>> Hi,
>>
>> As I'm looking to add some support to nouveau for features like atomic
>> counters and images, I'm running into some confusion about what the
>> first word of the shader header means. Here is the definition as we
>> have it today:
>
> [...]
>
>> However I know that these are somewhat wrong. I've seen shaders that
>> use gmem accesses (i.e. mov r0, [r0]) that just have the LMEM enable
>> bit set (and they use no lmem). And I've seen additional bits set, esp
>> relating to images, but I haven't spent enough time looking at all the
>> variations to make sense of it yet. For example, I think that Fermi
>> and Kepler+ have different meanings for some of the bits.
>
> Those look pretty close :)
>
>> I was hoping you could just release the docs for the shader headers,
>> or at least the first word of the shader header.
>
> We've posted the specification for the full Shader Program Header to our
> GPU documentation site here:
>
> ftp://download.nvidia.com/open-gpu-doc/Shader-Program-Header/1/Shader-Program-Header.html
>
> I hope it helps clear things up.

Yep, just a few follow-up questions:

- SPH Type 1 and type 2 appear to be flipped wrt the tables -- "When
PS is used, field SphType in CommonWord0 must be set to 1; similarly,
when VTG is used, SphType in CommonWord0 must be set to 2." But the
"Table 1. SPH Type 1 Definition" is clearly meant for VTG and table 2
is clearly meant for PS...
- You skip over SassVersion -- what is that?
- You have a funny note in there -- "Triangles generated by the
geometry shader always have all their edge flags set to TRUE" -- that
is the *only* reference to edge flags in the whole document. Right now
we do some crazy thing to get edge flags right on fermi+ (and I think
we just get them wrong on tesla). Is there a way to emit edge flags
from vertex shader?
- To be clear: DoesLoadOrStore -- *any* load/store? Even LDC? ALD?

Thanks!

  -ilia