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1Name
2
3    EXT_context_priority
4
5Name Strings
6
7    GLX_EXT_context_priority
8
9Contributors
10
11    Adam Jackson, Red Hat
12
13    Cloned from EGL_IMG_context_priority, whose contributors included:
14
15    Ben Bowman, Imagination Techonologies
16    Graham Connor, Imagination Techonologies
17
18Contacts
19
20    Adam Jackson <ajax@redhat.com>
21
22Status
23
24    Complete
25
26Version
27
28    Version 2, 10 April 2019
29
30Number
31
32    OpenGL Extension #535
33
34Dependencies
35
36    Requires GLX_ARB_create_context.
37
38    This extension is written against the text of the GLX 1.4 specification.
39
40Overview
41
42    This extension allows a GLXContext to be created with a priority
43    hint. It is possible that an implementation will not honour the
44    hint, especially if there are constraints on the number of high
45    priority contexts available in the system, or system policy limits
46    access to high priority contexts to appropriate system privilege
47    level. A query is provided to find the real priority level assigned
48    to the context after creation.
49
50New Types
51
52    None
53
54New Procedures and Functions
55
56    None
57
58New Tokens
59
60    New attributes accepted by the <attrib_list> argument of
61    glXCreateContextAttribsARB:
62
63        GLX_CONTEXT_PRIORITY_LEVEL_EXT          0x3100
64
65    New attribute values accepted in the <attrib_list> argument
66    of glXCreateContextAttribsARB:
67
68        GLX_CONTEXT_PRIORITY_HIGH_EXT           0x3101
69        GLX_CONTEXT_PRIORITY_MEDIUM_EXT         0x3102
70        GLX_CONTEXT_PRIORITY_LOW_EXT            0x3103
71
72Additions to the GLX_ARB_create_context specification
73
74    Add to the text of attributes supported by glXCreateContextAttribsARB:
75
76        "GLX_CONTEXT_PRIORITY_LEVEL_EXT determines the priority level of
77        the context to be created. This attribute is a hint, as an
78        implementation may not support multiple contexts at some
79        priority levels and system policy may limit access to high
80        priority contexts to appropriate system privilege level. The
81        default value for GLX_CONTEXT_PRIORITY_LEVEL_EXT is
82        GLX_CONTEXT_PRIORITY_MEDIUM_EXT."
83
84Additions to the GLX 1.4 specification
85
86    To Table 3.5 "Context attributes" add the row:
87
88    Attribute                       Type    Description
89    GLX_CONTEXT_PRIORITY_LEVEL_EXT  int     Context priority level
90
91Issues
92
93    Refer to the issues in EGL_IMG_context_priority for further background.
94
95    1) What enumerant values should we use here?
96
97    RESOLVED: Reuse the enums from EGL_IMG_context_priority. The window
98    system binding APIs have trended towards sharing enumerant space. The
99    range is not otherwise assigned for GLX, and Imagination have consented
100    to its reuse in GLX.
101
102Revision History
103
104    Version 2, 10 April 2019 (Adam Jackson)
105    - Resolve enumerant issue.
106
107    Version 1, 20 February 2019 (Adam Jackson)
108    - Clone from EGL_IMG_context_priority
109