[Mesa-dev] [PATCH 13/25] gallium: Introduce max_gl*version pipe-caps

[Emil Velikov]

On 22/02/14 21:46, Roland Scheidegger wrote:
> 
> 
> ----- Original Message -----
>> From: "Emil Velikov" <emil.l.velikov at gmail.com>
>> To: "Roland Scheidegger" <sroland at vmware.com>, mesa-dev at lists.freedesktop.org
>> Cc: "emil l velikov" <emil.l.velikov at gmail.com>
>> Sent: Saturday, February 22, 2014 2:02:08 PM
>> Subject: Re: [Mesa-dev] [PATCH 13/25] gallium: Introduce max_gl*version pipe-caps
>>
>> On 22/02/14 12:02, Roland Scheidegger wrote:
>>> Am 22.02.2014 04:04, schrieb Emil Velikov:
>>>> According to the GLX_MESA_query_renderer spec each driver should
>>>> be able to report the version of each GL api they support before
>>>> creating a context.
>>>>
>>>> Currently both classic mesa and gallium evaluate the version post
>>>> context creation and while the classic drivers set the max_gl*version
>>>> according to their capabilities, gallium uses fixed values which
>>>> are not the best approach due to driver differences.
>>>>
>>>> Add pipe-caps so that each driver can provide their individual
>>>> capabilites.
>>>>
>>>> Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
>>>> ---
>>>>  src/gallium/docs/source/screen.rst   | 8 +++++++-
>>>>  src/gallium/include/pipe/p_defines.h | 6 +++++-
>>>>  2 files changed, 12 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/src/gallium/docs/source/screen.rst
>>>> b/src/gallium/docs/source/screen.rst
>>>> index bd553f4..7b72133 100644
>>>> --- a/src/gallium/docs/source/screen.rst
>>>> +++ b/src/gallium/docs/source/screen.rst
>>>> @@ -169,7 +169,7 @@ The integer capabilities:
>>>>    since they are linked) a driver can support. Returning 0 is equivalent
>>>>    to returning 1 because every driver has to support at least a single
>>>>    viewport/scissor combination.
>>>> -* ''PIPE_CAP_ENDIANNESS``:: The endianness of the device.  Either
>>>> +* ``PIPE_CAP_ENDIANNESS``:: The endianness of the device.  Either
>>>>    PIPE_ENDIAN_BIG or PIPE_ENDIAN_LITTLE.
>>>>  * ``PIPE_CAP_MIXED_FRAMEBUFFER_SIZES``: Whether it is allowed to have
>>>>    different sizes for fb color/zs attachments. This controls whether
>>>> @@ -182,6 +182,12 @@ The integer capabilities:
>>>>    vertex components output by a single invocation of a geometry shader.
>>>>    This is the product of the number of attribute components per vertex
>>>>    and
>>>>    the number of output vertices.
>>>> +* ``PIPE_CAP_MAX_GL_CORE_VERSION``: The maximum OpenGL (Core profile)
>>>> version
>>>> +  supported.
>>>> +* ``PIPE_CAP_MAX_GL_COMPAT_VERSION``: The maximum OpenGL (Compatibility
>>>> profile)
>>>> +  version supported.
>>>> +* ``PIPE_CAP_MAX_GL_ES1_VERSION``: The maximum OpenGL ES1 version
>>>> supported.
>>>> +* ``PIPE_CAP_MAX_GL_ES2_VERSION``: The maximum OpenGL ES2 version
>>>> supported.
>>>>  
>>>>  
>>>>  .. _pipe_capf:
>>>> diff --git a/src/gallium/include/pipe/p_defines.h
>>>> b/src/gallium/include/pipe/p_defines.h
>>>> index 83815cd..5c27f9c 100644
>>>> --- a/src/gallium/include/pipe/p_defines.h
>>>> +++ b/src/gallium/include/pipe/p_defines.h
>>>> @@ -522,7 +522,11 @@ enum pipe_cap {
>>>>     PIPE_CAP_MIXED_FRAMEBUFFER_SIZES = 86,
>>>>     PIPE_CAP_TGSI_VS_LAYER = 87,
>>>>     PIPE_CAP_MAX_GEOMETRY_OUTPUT_VERTICES = 88,
>>>> -   PIPE_CAP_MAX_GEOMETRY_TOTAL_OUTPUT_COMPONENTS = 89
>>>> +   PIPE_CAP_MAX_GEOMETRY_TOTAL_OUTPUT_COMPONENTS = 89,
>>>> +   PIPE_CAP_MAX_GL_CORE_VERSION = 90,
>>>> +   PIPE_CAP_MAX_GL_COMPAT_VERSION = 91,
>>>> +   PIPE_CAP_MAX_GL_ES1_VERSION = 92,
>>>> +   PIPE_CAP_MAX_GL_ES2_VERSION = 93,
>>>>  };
>>>>  
>>>>  #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)
>>>>
>>>
>>> Hmm do you really need all these different cap bits? Generally, the
>>> difference between ES/CORE/COMPAT contexts isn't hw related at all, and
>>> thus not really (gallium) driver related. So, obviously, every driver
>>> can do ES11 for instance, it should be impossible to write a gallium
>>> driver which can't. Similarly, I don't think core/compat needs a
>>> different query neither, though I guess ES2 version being separate might
>>> make sense.
>>>
>> If you can think of a way to retrieve the gl* version that a driver
>> support without ever having a gl_context I would love to hear how we can
>> do that. GLX_MESA_query_renderer requires from the driver to state the
>> version of each api it supports prior of context creation.
>>
>> Honestly I felt a bit bad about adding all those caps, but this is the
>> least evasive way of handling it. I will drop the ES1 cap would love to
>> nuke the rest as well :-)
> 
> 
> I think you could easily derive compat and core version from some "gl driver
> version" instead of having two (the driver knows nothing about core or compat
> contexts, after all). ES might be different (at least with OES 4.0).
> But technically, you shouldn't even need any version queries as you could derive
> this from all the other cap bits I think (much the same way as st_extensions.c
> figures out what extensions are supported, plus mesa's compute_version then does).
> None of that cap query stuff (including querying for msaa formats and the like)
> requires a context. At least I can't see why it wouldn't work.
> 
Now that I think about it, one could copy the extension list and
(context) constants to pipe_screen. This way on st_api_create_context,
we'll just copy the initial values over. FWIW we'll still be able to
amend the extension list via MESA_EXTENSION_OVERRIDE, during the
_mesa_make_current call.

... or should I scrap this idea, and retrieve the extensions only to
discard them after the version is determined ?

Either way the core/compat version will look rather hacky, imho, but
other places of mesa seem to be using the same approach so I'll stick
with it.

if version > 31 {
 core = version;
 compat = 30;
} else {
 core = 0;
 compat = version;
}


Roland do you had something similar in mind or am I completely off from
what you're saying ?

Thanks
-Emil
> Roland
>