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authorIan Romanick <ian.d.romanick@intel.com>2013-02-15 22:38:23 -0800
committerIan Romanick <ian.d.romanick@intel.com>2013-11-07 18:12:33 -0800
commitee6c9fcbcaf525b13f23537f50e207bff57581d8 (patch)
tree80d42e3b763c7268c5e6ab9af582eb9850c10244
parent4680d237c5ae2d1ce6446ff2ec2f0a91f8286554 (diff)
docs: Import extension spec for GLX_MESA_query_renderer
The enumerated values are currently allocated from Intel's range. v2: Fix a typo. Update the list of functions to which the new enums can be passed. The "Current" versions were previously missing. Both things noticed by Marek. v3: Fix typo in return type of glXQueryRendererIntegerMESA in the spec body (noticed by Ken). Fix typo in issue #14 referencing itself instead of issue #13 (noticed by Dave). Signed-off-by: Ian Romanick <ian.d.romanick@intel.com> Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> Acked-by: Marek Olšák <marek.olsak@amd.com> Acked-by: Dave Airlie <airlied@redhat.com>
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+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
+
+ Incomplete. DO NOT SHIP.
+
+Version
+
+ Version 6, 7-November-2013
+
+Number
+
+ TBD.
+
+Dependencies
+
+ GLX 1.4 is required.
+
+ GLX_ARB_create_context and GLX_ARB_create_context_profile are required.
+
+ This extension interacts with GLX_EXT_create_context_es2_profile and
+ GLX_EXT_create_context_es_profile.
+
+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
+
+ Accepted as an attribute name in <*attrib_list> in
+ glXCreateContextAttribsARB:
+
+ GLX_RENDERER_ID_MESA 0x818E
+
+Additions to the OpenGL / WGL Specifications
+
+ None. This specification is written for GLX.
+
+Additions to the GLX 1.4 Specification
+
+ [Add the following to Section X.Y.Z 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.
+
+
+ [Add to section section 3.3.7 "Rendering Contexts"]
+
+ The attribute name GLX_RENDERER_ID_MESA specified the index of the render
+ against which the context should be created. The default value of
+ GLX_RENDER_ID_MESA is 0.
+
+
+ [Add to list of errors for glXCreateContextAttribsARB in section section
+ 3.3.7 "Rendering Contexts"]
+
+ * If the value of GLX_RENDERER_ID_MESA specifies a non-existent
+ renderer, BadMatch is generated.
+
+Dependencies on GLX_EXT_create_context_es_profile and
+GLX_EXT_create_context_es2_profile
+
+ If neither extension is supported, remove all mention of
+ GLX_RENDERER_OPENGL_ES2_PROFILE_VERSION_MESA from the spec.
+
+ If GLX_EXT_create_context_es_profile is not supported, remove all mention of
+ GLX_RENDERER_OPENGL_ES_PROFILE_VERSION_MESA from the spec.
+
+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
+ 0x168C, but GLX_RENDERER_DEVICE_ID_MESA will return 0x0000.
+
+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.