[PATCH xserver] glamor_egl: request GL2.1 when requesting Desktop GL context

[Icenowy Zheng]

于 2018年8月22日 GMT+08:00 下午8:24:09, Emil Velikov <emil.l.velikov at gmail.com> 写到:
>On 21 August 2018 at 17:01, Icenowy Zheng <icenowy at aosc.io> wrote:
>> Some devices cannot support OpenGL 2.1, which is the minimum desktop
>GL
>> version required by glamor. However, they may support OpenGL ES 2.0,
>> which is the GLES version required by glamor. Usually in this
>situation
>> the desktop GL version supported is 2.0 or 1.4.
>>
>> Currently, as no requirements are passed when creating desktop GL
>> context, a OpenGL 1.4/2.0 context will be created, and glamor will
>> arguing that the context is not suitable, although the GPU supports a
>> suitable GLES context.
>>
>> Add version number 2.1 requirement when requesting non-core desktop
>GL
>> context (core context has at least 3.1), so it will fall back to
>create
>> GLES contexts when the version number requirement is not met.
>>
>I don't know glamor enough to say if OpenGL 2.1 or another version
>should be required.

I think there's other code saying OpenGL 2.1 is required in glamor.c .

>Small mildly related note below.
>
>> Tested on a Intel 945GMS integrated GPU, which supports GL 1.4 and
>GLES
>> 2.0. Before applying this, it will fail to launch X server when no
>> configuration is present because of glamor initialization failure,
>after
>> applying glamor will start with GLES.
>>
>> Signed-off-by: Icenowy Zheng <icenowy at aosc.io>
>> ---
>>  glamor/glamor.h     | 4 ++++
>>  glamor/glamor_egl.c | 4 ++++
>>  2 files changed, 8 insertions(+)
>>
>> diff --git a/glamor/glamor.h b/glamor/glamor.h
>> index 09e9c895c..abee6a3e8 100644
>> --- a/glamor/glamor.h
>> +++ b/glamor/glamor.h
>> @@ -75,6 +75,10 @@ typedef Bool (*GetDrawableModifiersFuncPtr)
>(DrawablePtr draw,
>>  #define GLAMOR_GL_CORE_VER_MAJOR 3
>>  #define GLAMOR_GL_CORE_VER_MINOR 1
>>
>> +/* We need OpenGL 2.1 to work at least */
>> +#define GLAMOR_GL_VER_MAJOR 2
>> +#define GLAMOR_GL_VER_MINOR 1
>> +
>>  /* @glamor_init: Initialize glamor internal data structure.
>>   *
>>   * @screen: Current screen pointer.
>> diff --git a/glamor/glamor_egl.c b/glamor/glamor_egl.c
>> index b33d8ef15..8da8d2731 100644
>> --- a/glamor/glamor_egl.c
>> +++ b/glamor/glamor_egl.c
>> @@ -946,6 +946,10 @@ glamor_egl_init(ScrnInfoPtr scrn, int fd)
>>              EGL_NONE
>>          };
>>          static const EGLint config_attribs[] = {
>> +            EGL_CONTEXT_MAJOR_VERSION_KHR,
>> +           GLAMOR_GL_VER_MAJOR,
>> +           EGL_CONTEXT_MINOR_VERSION_KHR,
>The EGL attributes are part of EGL_KHR_create_context, which we do not
>check currently.
>Since EGL_CONTEXT_MAJOR_VERSION_KHR is effectively an alias for
>EGL_CONTEXT_CLIENT_VERSION one could use the latter and GL_VERSION of
>the created context.
>
>it's technically correct, although it feels like an overkill.
>Worth checking what others think on the topic.
>
>HTH
>Emil