+++ /dev/null
-Name
-
- MESA_query_renderer
-
-Name Strings
-
- GLX_MESA_query_renderer
-
-Contact
-
- Ian Romanick <ian.d.romanick@intel.com>
-
-IP Status
-
- No known IP claims.
-
-Status
-
- Shipping as of Mesa 10.0
-
-Version
-
- Version 9, 09 November 2018
-
-Number
-
- OpenGL Extension #446
-
-Dependencies
-
- GLX 1.4 is required.
-
- GLX_ARB_create_context and GLX_ARB_create_context_profile are required.
-
-Overview
-
- In many situations, applications want to detect characteristics of a
- rendering device before creating a context for that device. Information
- gathered at this stage may guide choices the application makes about
- color depth, number of samples per-pixel, texture quality, and so on.
- In addition, versions of supported APIs and implementation API
- preference may also guide start-up decisions made by the application.
- For example, one implementation may prefer vertex data be supplied using
- methods only available in a compatibility profile, but another
- implementation may only support the desired version in a core profile.
-
- There are also cases where more than one renderer may be available per
- display. For example, there is typically a hardware implementation and
- a software based implementation. There are cases where an application
- may want to pick one over the other. One such situation is when the
- software implementation supports more features than the hardware
- implementation. Another situation is when a particular version of the
- hardware implementation is blacklisted due to known bugs.
-
- This extension provides a mechanism for the application to query all of
- the available renderers for a particular display and screen. In
- addition, this extension provides a mechanism for applications to create
- contexts with respect to a specific renderer.
-
-New Procedures and Functions
-
- Bool glXQueryRendererIntegerMESA(Display *dpy, int screen,
- int renderer, int attribute,
- unsigned int *value);
- Bool glXQueryCurrentRendererIntegerMESA(int attribute, unsigned int *value);
-
- const char *glXQueryRendererStringMESA(Display *dpy, int screen,
- int renderer, int attribute);
-
- const char *glXQueryCurrentRendererStringMESA(int attribute);
-
-New Tokens
-
- Accepted as an <attribute> in glXQueryRendererIntegerMESA and
- glXQueryCurrentRendererIntegerMESA:
-
- GLX_RENDERER_VENDOR_ID_MESA 0x8183
- GLX_RENDERER_DEVICE_ID_MESA 0x8184
- GLX_RENDERER_VERSION_MESA 0x8185
- GLX_RENDERER_ACCELERATED_MESA 0x8186
- GLX_RENDERER_VIDEO_MEMORY_MESA 0x8187
- GLX_RENDERER_UNIFIED_MEMORY_ARCHITECTURE_MESA 0x8188
- GLX_RENDERER_PREFERRED_PROFILE_MESA 0x8189
- GLX_RENDERER_OPENGL_CORE_PROFILE_VERSION_MESA 0x818A
- GLX_RENDERER_OPENGL_COMPATIBILITY_PROFILE_VERSION_MESA 0x818B
- GLX_RENDERER_OPENGL_ES_PROFILE_VERSION_MESA 0x818C
- GLX_RENDERER_OPENGL_ES2_PROFILE_VERSION_MESA 0x818D
-
- Accepted as an <attribute> in glXQueryRendererStringMESA and
- glXQueryCurrentRendererStringMESA:
-
- GLX_RENDERER_VENDOR_ID_MESA
- GLX_RENDERER_DEVICE_ID_MESA
-
-Additions to the OpenGL / WGL Specifications
-
- None. This specification is written for GLX.
-
-Additions to the GLX 1.4 Specification
-
- [Add to Section 3.3.2 "GLX Versioning" of the GLX Specification]
-
- To obtain information about the available renderers for a particular
- display and screen,
-
- Bool glXQueryRendererIntegerMESA(Display *dpy, int screen, int renderer,
- int attribute, unsigned int *value);
-
- can be used. The value for <attribute> will be returned in one or more
- integers specified by <value>. The values, data sizes, and descriptions
- of each renderer attribute are listed in the table below.
-
- GLX renderer attribute number description
- of values
- ---------------------- --------- -----------
- GLX_RENDERER_VENDOR_ID_MESA 1 PCI ID of the device vendor
- GLX_RENDERER_DEVICE_ID_MESA 1 PCI ID of the device
- GLX_RENDERER_VERSION_MESA 3 Major, minor, and patch level of
- the renderer implementation
- GLX_RENDERER_ACCELERATED_MESA 1 Boolean indicating whether or
- not the renderer is hardware
- accelerated
- GLX_RENDERER_VIDEO_MEMORY_MESA 1 Number of megabytes of video
- memory available to the renderer
- GLX_RENDERER_UNIFIED_MEMORY_ARCHITECTURE_MESA
- 1 Boolean indicating whether or
- not the renderer uses a unified
- memory architecture or has
- separate "on-card" and GART
- memory.
- GLX_RENDERER_PREFERRED_PROFILE_MESA
- 1 Bitmask of the preferred context
- profile for this renderer. This
- value is suitable to be supplied
- with the
- GLX_CONTEXT_PROFILE_MASK_ARB
- attribute to
- glXCreateContextAttribsARB
- GLX_RENDERER_OPENGL_CORE_PROFILE_VERSION_MESA
- 2 Maximum core profile major and
- minor version supported by the
- renderer
- GLX_RENDERER_OPENGL_COMPATIBILITY_PROFILE_VERSION_MESA
- 2 Maximum compatibility profile
- major and minor version
- supported by the renderer
- GLX_RENDERER_OPENGL_ES_PROFILE_VERSION_MESA
- 2 Maximum OpenGL ES 1.x
- major and minor version
- supported by the renderer
- GLX_RENDERER_OPENGL_ES2_PROFILE_VERSION_MESA
- 2 Maximum OpenGL ES 2.x or 3.x
- major and minor version
- supported by the renderer
-
- In the table, boolean attributes will have either the value 0 or 1.
-
- GLX_RENDERER_OPENGL_CORE_PROFILE_VERSION_MESA,
- GLX_RENDERER_OPENGL_COMPATIBILITY_PROFILE_VERSION_MESA,
- GLX_RENDERER_OPENGL_ES_PROFILE_VERSION_MESA, and
- GLX_RENDERER_OPENGL_ES2_PROFILE_VERSION_MESA each return <0, 0> in
- *value if no version of that profile is supported.
-
- GLX_RENDERER_VENDOR_ID_MESA and GLX_RENDERER_DEVICE_ID_MESA may return
- 0xFFFFFFFF if the device does not have a PCI ID (because it is not a PCI
- device) or if the PCI ID is not available. In this case the application
- should rely on the string query instead.
-
- If <attribute> is not a recognized value, False is returned, but no GLX
- error is generated. Otherwise, True is returned.
-
- String versions of some attributes may also be queried using
-
- const char *glXQueryRendererStringMESA(Display *dpy, int screen,
- int renderer, int attribute);
-
- The value for <attribute> will be returned in one or more
- integers specified by <value>. The values, data sizes, and descriptions
- of each renderer attribute are listed in the table below.
-
- GLX renderer attribute description
- ---------------------- -----------
- GLX_RENDERER_VENDOR_ID_MESA Name of the renderer provider. This may
- differ from the vendor name of the
- underlying hardware.
- GLX_RENDERER_DEVICE_ID_MESA Name of the renderer. This may differ from
- the name of the underlying hardware (e.g.,
- for a software renderer).
-
- If <attribute> is not a recognized value, NULL is returned, but no GLX
- error is generated.
-
- The string returned for GLX_RENDERER_VENDOR_ID_MESA will have the same
- format as the string that would be returned by glGetString of GL_VENDOR.
- It may, however, have a different value.
-
- The string returned for GLX_RENDERER_DEVICE_ID_MESA will have the same
- format as the string that would be returned by glGetString of GL_RENDERER.
- It may, however, have a different value.
-
-Issues
-
- 1) How should the difference between on-card and GART memory be exposed?
-
- UNRESOLVED.
-
- 2) How should memory limitations of unified memory architecture (UMA)
- systems be exposed?
-
- UNRESOLVED. Some hardware has different per-process and global
- limits for memory that can be accessed within a single draw call.
-
- 3) How should the renderer's API preference be advertised?
-
- UNRESOLVED. The common case for desktop renderers is to prefer
- either core or compatibility. However, some renderers may actually
- prefer an ES context. This leaves the application in a tough spot
- if it can only support core or compatibility and the renderer says it
- wants ES.
-
- 4) Should OpenGL ES 2.0 and OpenGL ES 3.0 be treated separately?
-
- RESOLVED. No. OpenGL ES 3.0 is backwards compatible with OpenGL ES
- 2.0. Applications can detect OpenGL ES 3.0 support by querying
- GLX_RENDERER_OPENGL_ES2_PROFILE_VERSION_MESA.
-
- 5) How can applications tell the difference between different hardware
- renderers for the same device? For example, whether the renderer is the
- open-source driver or the closed-source driver.
-
- RESOLVED. Assuming this extension is ever implemented outside Mesa,
- applications can query GLX_RENDERER_VENDOR_ID_MESA from
- glXQueryRendererStringMESA. This will almost certainly return
- different strings for open-source and closed-source drivers.
-
- 6) What is the value of GLX_RENDERER_UNIFIED_MEMORY_ARCHITECTURE_MESA for
- software renderers?
-
- UNRESOLVED. Video (display) memory and texture memory is not unified
- for software implementations, so it seems reasonable for this to be
- False.
-
- 7) How does an application determine the number of available renderers?
-
- UNRESOLVED.
-
- 8) What happens if a fbconfig is used to create context on a renderer
- that cannot support it? For example, if a multisampled config is used
- with a software renderer that does not support multisampling.
-
- RESOLVED. The language for glXCreateContextAttribsARB already covers
- this case. Context creation will fail, and BadMatch is generated.
-
- 9) In addition to being able to query the supported versions, should
- applications also be able to query the supported extensions?
-
- RESOLVED. No. Desktop OpenGL core profiles and OpenGL ES 3.0 have
- moved away from the monolithic string returned by glGetString of
- GL_EXTENSIONS. Providing the newer indexed query would require adding
- a lot of extra infrastructure, and it would probably provide little
- benefit to applications.
-
- 10) What combination of values for GLX_RENDERER_PREFERRED_PROFILE_MESA,
- GLX_RENDERER_OPENGL_COMPATIBILITY_PROFILE_VERSION_MESA, and
- GLX_RENDERER_OPENGL_CORE_PROFILE_VERSION_MESA should be returned
- for a renderer that only supports OpenGL 3.1 without the
- GL_ARB_compatibility extension?
-
- RESOLVED. The renderer will return GLX_CONTEXT_CORE_PROFILE_BIT_ARB
- for GLX_RENDERER_PREFERRED_PROFILE_MESA.
-
- Further, the renderer will return <3,0> for
- GLX_RENDERER_OPENGL_COMPATIBILITY_PROFILE_VERSION_MESA because OpenGL
- 3.1 without GL_ARB_compatibility is not backwards compatible with
- previous versions of OpenGL. The render will return <3,1> for
- GLX_RENDERER_OPENGL_CORE_PROFILE_VERSION_MESA indicating that support
- for OpenGL 3.1 is available.
-
- Even though there is no OpenGL 3.1 core profile, the values
- returned for GLX_RENDERER_PREFERRED_PROFILE_MESA and
- GLX_RENDERER_OPENGL_CORE_PROFILE_VERSION_MESA can be supplied
- with the GLX_CONTEXT_PROFILE_MASK_ARB and
- GLX_CONTEXT_{MAJOR,MINOR}_VERSION_ARB attributes of
- glXCreateContextAttribsARB without error. If the requested
- OpenGL version is less than 3.2, the
- GLX_CONTEXT_PROFILE_MASK_ARB attribute is ignored by
- glXCreateContextAttribsARB.
-
- 11) How can application learn about multi-GPU (e.g., SLI, CrossFireX,
- etc.) configurations?
-
- UNRESOLVED. Based on ISV feedback, this is important information to
- provide to the application. Given the variety of possible hardware
- configurations (e.g., Hybrid CrossFireX) and different rendering
- modes (e.g., split-frame rendering vs. alternate-frame rendering),
- it's not clear how this information can be communicated.
-
- It is likely that this will be left to a layered extension.
-
- 12) Should capability queries similar to those in
- GL_ARB_internalformat_query or GL_ARB_internalformat_query2 be added?
-
- RESOLVED. No. With the possible exception of the texture size
- queries, it seems unlikely that applications would ever use this
- information before creating a context.
-
- 13) Existing GL extensions (e.g., GL_ATI_meminfo and
- GL_NVX_gpu_memory_info) allow easy queries after context creation. With
- this extension it is a bit of a pain for a portable application to query
- the information after context creation.
-
- RESOLVED. Add versions of the queries that implicitly take the
- display, screen, and renderer from the currently bound context.
-
- 14) Why not make the queries from issue #13 GL functions (instead of GLX)?
-
- RESOLVED. It is fairly compelling for the post-creation queries to
- just use glGetInteger and glGetString. However, the GL enums and
- the GLX enums would have different names and would almost certainly
- have different values. It seems like this would cause more problems
- than it would solve.
-
- 15) Should the string queries be required to return the same values as
- glGetString(GL_VENDOR) and glGetString(GL_RENDERER)?
-
- UNRESOLVED. This may be useful for applications that already do
- device detection based on these strings.
-
- 16) What type should the value parameter of glXQueryRendererIntegerMESA
- and glXQueryCurrentRendererIntegerMESA be?
-
- UNRESOLVED. Other similar GLX query functions just use int or
- unsigned int, so that's what this extension uses for now. However,
- an expeclitly sized value, such as uint32_t or uint64_t, seems
- preferable.
-
- 17) What about SoCs and other systems that don't have PCI?
-
- RESOLVED. The GLX_RENDERER_VENDOR_ID_MESA and
- GLX_RENDERER_DEVICE_ID_MESA integer queries may return 0xFFFFFFFF if a
- PCI ID either does not exist or is not available. Implementations
- should make every attempt to return as much information as is
- possible. For example, if the implementation is running on a non-PCI
- SoC with a Qualcomm GPU, GLX_RENDERER_VENDOR_ID_MESA should return
- 0x5143, but GLX_RENDERER_DEVICE_ID_MESA will return 0xFFFFFFFF.
-
-Revision History
-
- Version 1, 2012/08/27 - Initial version
-
- Version 2, 2012/09/04 - Specify behavior of implementations that
- do not support certain profiles.
- Change wording of issue #8 to be more
- clear.
- Make some wording changes to issue #10 to
- clarify the resolution a bit.
-
- Version 3, 2012/09/23 - Add issue #11 regarding multi-GPU systems.
-
- Version 4, 2013/02/01 - Add issue #12 regarding texture / renderbuffer
- format queries.
-
- Version 5, 2013/02/14 - Add issues #13 and #14 regarding simpler queires
- after the context is created and made current.
- Add issue #15 regarding the string query.
- Add issue #16 regarding the value type returned
- by the Integer functions.
-
- Version 6, 2013/10/25 - Fix a typo. Update the list of functions to
- which the new enums can be passed. The "Current"
- versions were previously missing.
-
- Version 7, 2013/11/07 - Fix a couple more typos. Add issue #17 regarding
- the PCI queries on systems that don't have PCI.
-
- Version 8, 2014/02/14 - Fix a couple typos. GLX_RENDER_ID_MESA should
- read GLX_RENDERER_ID_MESA. The VENDOR/DEVICE_ID
- example given in issue #17 should be 0x5143 and
- 0xFFFFFFFF respectively.
-
- Version 9, 2018/11/09 - Remove GLX_RENDERER_ID_MESA, which has never been
- implemented. Remove the unnecessary interactions
- with the GLX GLES profile extensions. Note the
- official GL extension number. Specify the section
- of the GLX spec to modify.
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