On Wed, Mar 7, 2018 at 11:44 AM, Ian Romanick <i...@freedesktop.org> wrote:
> On 03/06/2018 03:27 PM, Marek Olšák wrote:
>> From: Marek Olšák <marek.ol...@amd.com>
>>
>> ---
>>  docs/envvars.html       |  3 ++-
>>  src/mesa/main/version.c | 16 +++++-----------
>>  2 files changed, 7 insertions(+), 12 deletions(-)
>>
>> diff --git a/docs/envvars.html b/docs/envvars.html
>> index ea42a50..3ef3ab1 100644
>> --- a/docs/envvars.html
>> +++ b/docs/envvars.html
>> @@ -92,22 +92,23 @@ glGetString(GL_VERSION) and possibly the GL API type.
>>  <li> FC is an optional suffix that indicates a forward compatible context.
>>  This is only valid for versions &gt;= 3.0.
>>  <li> GL versions &lt; 3.0 are set to a compatibility (non-Core) profile
>>  <li> GL versions = 3.0, see below
>>  <li> GL versions &gt; 3.0 are set to a Core profile
>>  <li> Examples: 2.1, 3.0, 3.0FC, 3.1, 3.1FC
>>  <ul>
>>  <li> 2.1 - select a compatibility (non-Core) profile with GL version 2.1
>>  <li> 3.0 - select a compatibility (non-Core) profile with GL version 3.0
>>  <li> 3.0FC - select a Core+Forward Compatible profile with GL version 3.0
>> -<li> 3.1 - select a Core profile with GL version 3.1
>> +<li> 3.1 - keep the same profile and set GL version 3.1
>>  <li> 3.1FC - select a Core+Forward Compatible profile with GL version 3.1
>> +<li> 3.1COMPAT - select a compatibility (non-Core) profile with GL version 
>> 3.1
>
> I don't think we should mention profiles here.  Before OpenGL 3.2 there
> is no such thing as a profile.  It doesn't exist.  I think this is more
> accurate:
>
> <li> 3.1 - Select OpenGL 3.1.  GL_ARB_compatibility will be enabled per the 
> driver default.
> <li> 3.1FC - Select OpenGL 3.1 with forward compatibility enabled.  
> GL_ARB_compatibilty will not be enabled.
> <li> 3.1COMPAT - Select OpenGL 3.1 with GL_ARB_compatibilty forced enabled.
>
>>  </ul>
>>  <li> Mesa may not really implement all the features of the given version.
>>  (for developers only)
>>  </ul>
>>  <li>MESA_GLES_VERSION_OVERRIDE - changes the value returned by
>>  glGetString(GL_VERSION) for OpenGL ES.
>>  <ul>
>>  <li> The format should be MAJOR.MINOR
>>  <li> Examples: 2.0, 3.0, 3.1
>>  <li> Mesa may not really implement all the features of the given version.
>> diff --git a/src/mesa/main/version.c b/src/mesa/main/version.c
>> index a280690..9ad49db 100644
>> --- a/src/mesa/main/version.c
>> +++ b/src/mesa/main/version.c
>> @@ -133,48 +133,42 @@ create_version_string(struct gl_context *ctx, const 
>> char *prefix)
>>     }
>>  }
>>
>>  /**
>>   * Override the context's version and/or API type if the
>>   * environment variable MESA_GL_VERSION_OVERRIDE is set.
>>   *
>>   * Example uses of MESA_GL_VERSION_OVERRIDE:
>>   *
>>   * 2.1: select a compatibility (non-Core) profile with GL version 2.1
>> - * 3.0: select a compatibility (non-Core) profile with GL version 3.0
>> - * 3.0FC: select a Core+Forward Compatible profile with GL version 3.0
>> - * 3.1: select a Core profile with GL version 3.1
>> - * 3.1FC: select a Core+Forward Compatible profile with GL version 3.1
>> + * X.Y: override GL version to X.Y without changing the profile
>> + * X.YFC: select a Core+Forward Compatible profile with GL version X.Y
>> + * X.YCOMPAT: select a Compatibility profile with GL version X.Y
>>   */
>>  bool
>>  _mesa_override_gl_version_contextless(struct gl_constants *consts,
>>                                        gl_api *apiOut, GLuint *versionOut)
>>  {
>>     int version;
>>     bool fwd_context, compat_context;
>>
>>     get_gl_override(*apiOut, &version, &fwd_context, &compat_context);
>>
>>     if (version > 0) {
>>        *versionOut = version;
>>
>> -      /* If the API is a desktop API, adjust the context flags.  We may also
>> -       * need to modify the API depending on the version.  For example, Mesa
>> -       * does not support a GL 3.3 compatibility profile.
>> -       */
>> +      /* Modify the API and context flags as needed. */
>>        if (*apiOut == API_OPENGL_CORE || *apiOut == API_OPENGL_COMPAT) {
>>           if (version >= 30 && fwd_context) {
>>              *apiOut = API_OPENGL_CORE;
>>              consts->ContextFlags |= GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT;
>> -         } else if (version >= 31 && !compat_context) {
>> -            *apiOut = API_OPENGL_CORE;
>> -         } else {
>> +         } else if (compat_context) {
>
> I seem to have missed what it is we're trying to fix.  Without this
> patch, if I run 'MESA_GL_VERSION_OVERRIDE=3.1 glxinfo | grep version' I
> get more or less the behavior that I expect:
>
>     Max core profile version: 3.1
>     Max compat profile version: 3.0
> OpenGL version string: 3.1 (Core Profile) Mesa 18.1.0-devel (git-877efedf4a)
> OpenGL shading language version string: 4.50
>
> I am wondering where the non-core profile version information is. :(
>
> With this patch, I get
>
>     Max core profile version: 4.5
>     Max compat profile version: 3.1
> OpenGL core profile version string: 3.1 (Core Profile) Mesa 18.1.0-devel 
> (git-cd435e0882)
> OpenGL core profile shading language version string: 4.50
> OpenGL version string: 3.1 Mesa 18.1.0-devel (git-cd435e0882)
> OpenGL shading language version string: 4.50
>
> Which doesn't seem right... but maybe I'm misunderstanding.  With this
> patch, 'MESA_GL_VERSION_OVERRIDE=3.1FC glxinfo | grep version' gives the
> same behavior as =3.1 without the patch.
>
> Without this change, MESA_GL_VERSION_OVERRIDE=3.2 seems pretty broken:
>
>     Max core profile version: 3.2
>     Max compat profile version: 3.0
> OpenGL core profile version string: 3.2 (Core Profile) Mesa 18.1.0-devel 
> (git-877efedf4a)
> OpenGL core profile shading language version string: 4.50
> Mesa: User error: GL_INVALID_ENUM in glGetString(GL_EXTENSIONS)
> OpenGL version string: 3.2 (Core Profile) Mesa 18.1.0-devel (git-877efedf4a)
> OpenGL shading language version string: 4.50

It's supposed to remove "version >= 31" from the conditional since
3.1 with ARB_compatibility is also possible. The behavior of the
version override is too shady already, so I don't care too much about
this.

Marek
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