[Mesa-dev] [RFC] [PATCH 1/2] mesa: let GL3 buf obj queries not depend on opengl major version

[Chris Bandy]

On 09/19/2011 12:12 PM, Jose Fonseca wrote:
> ----- Original Message -----
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>> On 09/19/2011 07:20 AM, Brian Paul wrote:
>>> On 09/19/2011 04:25 AM, Yuanhan Liu wrote:
>>>> If I understand correctly, the new GL3 buffer object queries
>>>> parameters, like BUFFER_MAP_ACCESS_FLAGS, depends on
>>>> ARB_map_buffer_range extension.
>>> That would make sense, but in fact the extension spec
>>> (http://www.opengl.org/registry/specs/ARB/map_buffer_range.txt)
>>> says nothing about these queries.  They were added in GL 3.0.
>> It seems like this could be an error in the extension spec.  This is
>> one of the extensions, like ARB_framebuffer_object, that "back ports"
>> OpenGL 3.0 functionality to previous versions.  These extensions are
>> supposed to provide *identical* functionality to OpenGL 3.0.  The
>> other cases of mismatches have been determined to be bugs in the
>> extension specs.
> FWIW, this ability would be useful for GL debuggers such as apitrace.  Otherwise the ARB_map_buffer_range extension is unbalanced: it adds new state that can never be queried. 
>
>> The question is, what do other implementations do?  The other other
>> question is, are there any implementations that support
>> ARB_map_buffer_range but not OpenGL 3.0?
> Very good questions...
>
> The answer to the later question can be obtained by data mining openbenchmarking.org, by entering this query on google:
>
>    site:openbenchmarking.org GL_ARB_map_buffer_range glxinfo "OpenGL version string: 2.1" -mesa
>
> and there are a few NVIDIA cards / driver combinations out there that hit this:
>
> OpenGL vendor string: NVIDIA Corporation
> OpenGL renderer string: GeForce 7900 GT/GTO/PCI/SSE2
> OpenGL version string: 2.1.2 NVIDIA 260.19.36
>
> OpenGL vendor string: NVIDIA Corporation
> OpenGL renderer string: Quadro FX 3450/4000 SDI/PCI/SSE2
> OpenGL version string: 2.1.2 NVIDIA 195.36.31
>
> OpenGL vendor string: NVIDIA Corporation
> OpenGL renderer string: GeForce Go 7400/PCI/SSE2
> OpenGL version string: 2.1.2 NVIDIA 270.29
>
> OpenGL vendor string: NVIDIA Corporation
> OpenGL renderer string: GeForce Go 7900 GS/PCI/SSE2
> OpenGL version string: 2.1.2 NVIDIA 260.19.06
>
> OpenGL vendor string: NVIDIA Corporation
> OpenGL renderer string: GeForce 7600 GT/PCI/SSE2
> OpenGL version string: 2.1.2 NVIDIA 270.30

I have this card but an older version of the driver. It claims to
support GL_ARB_map_buffer_range. Attached is my full output from
`nvidia-settings -g`.

  OpenGL vendor string: NVIDIA Corporation
  OpenGL renderer string: GeForce 7600 GT/PCI/SSE2
  OpenGL version string: 2.1.2 NVIDIA 260.19.29

-- Chris

> If anybody had one of these, we could tell for sure.
>
> Jose
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