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NAME
clCreateContextFromType - Create an OpenCL context from a device type that identifies the
specific device(s) to use.
cl_context clCreateContextFromType(const cl_context_properties *properties,
cl_device_type device_type,
void (CL_CALLBACK *pfn_notify) (const char *errinfo,
const void *private_info, size_t cb, void *user_data),
void *user_data, cl_int *errcode_ret);
PARAMETERS
properties
Specifies a list of context property names and their corresponding values. Each
property name is immediately followed by the corresponding desired value. The list of
supported properties is described in the table below. properties can also be NULL in
which case the platform that is selected is implementation-defined.
If the cl_khr_gl_sharing(3clc) extension is supported, properties points to an
attribute list whose format and valid contents are identical to the properties
argument of clCreateContext(3clc) which is: properties specifies a list of context
property names and their corresponding values. Each property name is immediately
followed by the corresponding desired value. The list is terminated with 0. The list
of supported properties is described in the table below. properties can be NULL in
which case the platform that is selected is implementation-defined.
┌──────────────────────────────┬──────────────────────────┬────────────────────────────────┐
│cl_context_properties │ Property value │ Description │
│enum │ │ │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CONTEXT_PLATFORM │ cl_platform_id │ Specifies the platform │
│ │ │ to use. │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CONTEXT_INTEROP_USER_SYNC │ cl_bool │ Specifies whether the │
│ │ │ user is responsible for │
│ │ │ synchronization between │
│ │ │ OpenCL and other APIs. │
│ │ │ Please refer to the │
│ │ │ specific sections in the │
│ │ │ OpenCL 1.2 extension │
│ │ │ specification that │
│ │ │ describe sharing with │
│ │ │ other APIs for │
│ │ │ restrictions on using │
│ │ │ this flag. If │
│ │ │ CL_CONTEXT_INTEROP_USER_SYNC │
│ │ │ is not specified, a │
│ │ │ default of CL_FALSE is │
│ │ │ assumed. │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CONTEXT_D3D10_DEVICE_KHR │ ID3D10Device * │ Specifies the ID3D10Device * │
│ │ │ to use for Direct3D 10 │
│ │ │ interoperability. The │
│ │ │ default value is NULL │
│ │ │ (applies if the extension │
│ │ │ cl_khr_d3d10_sharing(3clc) │
│ │ │ is supported) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CONTEXT_ADAPTER_D3D9_KHR │ IDirect3DDevice9 * │ Specifies an │
│ │ │ IDirect3DDevice9 to use for │
│ │ │ D3D9 intero (applies if the │
│ │ │ cl_khr_dx9_media_sharing(3clc) │
│ │ │ extension is supported) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CONTEXT_ADAPTER_D3D9EX_KHR │ IDirect3DDeviceEx* │ Specifies an │
│ │ │ IDirect3DDevice9Ex to use for │
│ │ │ D3D9 interop (applies if the │
│ │ │ cl_khr_dx9_media_sharing(3clc) │
│ │ │ extension is supported) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CONTEXT_ADAPTER_DXVA_KHR │ IDXVAHD_Device * │ Specifies an IDXVAHD_Device to │
│ │ │ use for DXVA interop (applies │
│ │ │ if the │
│ │ │ cl_khr_dx9_media_sharing(3clc) │
│ │ │ extension is supported) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_GL_CONTEXT_KHR │ 0, OpenGL context handle │ OpenGL context to associated │
│ │ │ the OpenCL context with │
│ │ │ (available if the │
│ │ │ cl_khr_gl_sharing(3clc) │
│ │ │ extension is enabled) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CGL_SHAREGROUP_KHR │ 0, CGL share group │ CGL share group to associate │
│ │ handle │ the OpenCL context with │
│ │ │ (available if the │
│ │ │ cl_khr_gl_sharing(3clc) │
│ │ │ extension is enabled) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_EGL_DISPLAY_KHR │ EGL_NO_DISPLAY, │ CGL share group to associate │
│ │ EGLDisplay handle │ the OpenCL context with │
│ │ │ (available if the │
│ │ │ cl_khr_gl_sharing(3clc) │
│ │ │ extension is enabled) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_GLX_DISPLAY_KHR │ None, X handle │ X Display an OpenGL context │
│ │ │ was created with respect to │
│ │ │ (available if the │
│ │ │ cl_khr_gl_sharing(3clc) │
│ │ │ extension is enabled) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_WGL_HDC_KHR │ 0, HDC handle │ HDC an OpenGL context was │
│ │ │ created with respect to │
│ │ │ (available if the │
│ │ │ cl_khr_gl_sharing(3clc) │
│ │ │ extension is enabled) │
├──────────────────────────────┼──────────────────────────┼────────────────────────────────┤
│CL_CONTEXT_D3D11_DEVICE_KHR │ ID3D11Device * │ Specifies the ID3D11Device * │
│ │ │ to use for Direct3D 11 │
│ │ │ interoperability. The default │
│ │ │ value is NULL * (applies if │
│ │ │ the cl_khr_d3d11_sharing(3clc) │
│ │ │ extension is supported) │
└──────────────────────────────┴──────────────────────────┴────────────────────────────────┘
device_type
A bit-field that identifies the type of device and is described in the table below.
┌───────────────────────────┬──────────────────────────────────┐
│cl_device_type │ Description │
├───────────────────────────┼──────────────────────────────────┤
│CL_DEVICE_TYPE_CPU │ An OpenCL device that is the │
│ │ host processor. The host │
│ │ processor runs the OpenCL │
│ │ implementations and is a single │
│ │ or multi-core CPU. │
├───────────────────────────┼──────────────────────────────────┤
│CL_DEVICE_TYPE_GPU │ An OpenCL device that is a GPU. │
│ │ By this we mean that the device │
│ │ can also be used to accelerate a │
│ │ 3D API such as OpenGL or │
│ │ DirectX. │
├───────────────────────────┼──────────────────────────────────┤
│CL_DEVICE_TYPE_ACCELERATOR │ Dedicated OpenCL accelerators │
│ │ (for example the IBM CELL │
│ │ Blade). These devices │
│ │ communicate with the host │
│ │ processor using a peripheral │
│ │ interconnect such as PCIe. │
├───────────────────────────┼──────────────────────────────────┤
│CL_DEVICE_TYPE_CUSTOM │ Dedicated accelerators that do │
│ │ not support programs written in │
│ │ OpenCL C. │
├───────────────────────────┼──────────────────────────────────┤
│CL_DEVICE_TYPE_DEFAULT │ The default OpenCL device in the │
│ │ system. The default device │
│ │ cannot be a │
│ │ CL_DEVICE_TYPE_CUSTOM device. │
├───────────────────────────┼──────────────────────────────────┤
│CL_DEVICE_TYPE_ALL │ All OpenCL devices available in │
│ │ the system except │
│ │ CL_DEVICE_TYPE_CUSTOM devices. │
└───────────────────────────┴──────────────────────────────────┘
pfn_notify
A callback function that can be registered by the application. This callback function
will be used by the OpenCL implementation to report information on errors that occur
in this context. This callback function may be called asynchronously by the OpenCL
implementation. It is the application's responsibility to ensure that the callback
function is thread-safe. If pfn_notify is NULL, no callback function is registered.
The parameters to this callback function are:
errinfo is a pointer to an error string.
private_info and cb represent a pointer to binary data that is returned by the OpenCL
implementation that can be used to log additional information helpful in debugging the
error.
user_data is a pointer to user supplied data.
There are a number of cases where error notifications need to be delivered due to an
error that occurs outside a context. Such notifications may not be delivered through
the pfn_notify callback. Where these notifications go is implementation-defined.
user_data
Passed as the user_data argument when pfn_notify is called. user_data can be NULL.
errcode_ret
Return an appropriate error code. If errcode_ret is NULL, no error code is returned.
DESCRIPTION
Only devices that are returned by clGetDeviceIDs(3clc) for device_type are used to create
the context. The context does not reference any sub-devices that may have been created
from these devices.
NOTES
clCreateContextFromType may return all or a subset of the actual physical devices present
in the platform and that match device_type.
clCreateContextFromType and clCreateContext(3clc) perform an implicit retain. This is very
helpful for 3rd party libraries, which typically get a context passed to them by the
application. However, it is possible that the application may delete the context without
informing the library. Allowing functions to attach to (i.e. retain) and release a context
solves the problem of a context being used by a library no longer being valid.
ERRORS
clCreateContextFromType returns a valid non-zero context and errcode_ret is set to
CL_SUCCESS if the context is created successfully. Otherwise, it returns a NULL value with
the following error vlaues returned in errcode_ret:
• CL_INVALID_PLATFORM if properties is NULL and no platform could be selected or if
platform value specified in properties is not a valid platform. If the
cl_khr_gl_sharing(3clc) extension is supported, this error is replaced (or not) by
CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR and possibly CL_INVALID_OPERATION (see below
and section 9.6.4 of the spec for clarification). .RE
• CL_INVALID_PROPERTY if context property name in properties is not a supported
property name, or if the value specified for a supported property name is not
valid, or if the same property name is specified more than once.
• CL_INVALID_VALUE if pfn_notify is NULL but user_data is not NULL.
• CL_INVALID_DEVICE_TYPE if device_type is not a valid value.
• CL_DEVICE_NOT_AVAILABLE if no devices that match device_type and property values
specified in properties are currently available.
• CL_DEVICE_NOT_FOUND if no devices that match device_type and property values
specified in properties were found.
• CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the
OpenCL implementation on the device.
• CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the
OpenCL implementation on the host.
• CL_INVALID_D3D10_DEVICE_KHR if the Direct3D 10 device specified for
interoperability is not compatible with the devices against which the context is
to be created (if the cl_khr_d3d10_sharing(3clc) extension is enabled).
• CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR when an invalid OpenGL context or share
group object handle is specified in properties if the cl_khr_gl_sharing(3clc)
extension is enabled.
• CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR: If no OpenGL or OpenGL ES context or share
group is specified in the attribute list, then memory objects may not be shared,
and calling any of the commands in section 9.7 will result in this error (if the
cl_khr_gl_sharing(3clc) extension is enabled).
• CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR if the cl_khr_gl_sharing(3clc) extension
is enabled and if a context was specified by any of the following means:
• Context specified for an EGL-based OpenGL ES or OpenGL implementation by
setting the attributes CL_GL_CONTEXT_KHR and CL_EGL_DISPLAY_KHR.
• Context was specified for a GLX-based OpenGL implementation by setting the
attributes CL_GL_CONTEXT_KHR and CL_GLX_DISPLAY_KHR.
• Context was specified for a WGL-based OpenGL implementation by setting the
attributes CL_GL_CONTEXT_KHR and CL_WGL_HDC_KHR.
and any of the following conditions hold:
• The specified display and context attributes do not identify a valid OpenGL
or OpenGL ES context.
• The specified context does not support buffer and renderbuffer objects.
• The specified context is not compatible with the OpenCL context being created
(for example, it exists in a physically distinct address space, such as
another hardware device, or does not support sharing data with OpenCL due to
implementation restrictions).
• CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR if a share group was specified for a
CGL-based OpenGL implementation by setting the attribute CL_CGL_SHAREGROUP_KHR,
and the specified share group does not identify a valid CGL share group object
(only if the cl_khr_gl_sharing(3clc) extension is enabled).
• CL_INVALID_DX9_MEDIA_ADAPTER_KHR if the media adapter specified for
interoperability is not compatible with the devices against which the context is
to be created (only if the cl_khr_dx9_media_sharing(3clc) extension is supported).
• CL_INVALID_ADAPTER_KHR if any of the values of the properties
CL_CONTEXT_ADAPTER_D3D9_KHR, CL_CONTEXT_ADAPTER_D3D9EX_KHR or
CL_CONTEXT_ADAPTER_DXVA_KHR is non-NULL and does not specify a valid media adapter
with which the cl_device_ids against which this context is to be created may
interoperate. (only if the cl_khr_dx9_media_sharing(3clc) extension is supported).
• CL_INVALID_OPERATION if interoperability is specified by setting
CL_CONTEXT_ADAPTER_D3D9_KHR, CL_CONTEXT_ADAPTER_D3D9EX_KHR or
CL_CONTEXT_ADAPTER_DXVA_KHR to a non-NULL value, and interoperability with another
graphics API is also specified. (only if the cl_khr_dx9_media_sharing(3clc)
extension is supported).
• CL_INVALID_D3D11_DEVICE_KHR if the Direct3D 11 device specified for
interoperability is not compatible with the devices against which the context is
to be created (only if the cl_khr_d3d11_sharing(3clc) extension is supported).
• CL_INVALID_OPERATION if Direct3D 11 interoperability is specified by setting
CL_INVALID_D3D11_DEVICE_KHR to a non-NULL value, and interoperability with another
graphics API is also specified. (only if the cl_khr_d3d11_sharing(3clc) extension
is supported).
• CL_INVALID_D3D11_DEVICE_KHR if the value of the property
CL_CONTEXT_D3D11_DEVICE_KHR is non-NULL and does not specify a valid Direct3D 11
device with which the cl_device_ids against which this context is to be created
may interoperate. (only if the cl_khr_d3d11_sharing(3clc) extension is supported).
SPECIFICATION
OpenCL Specification[1]
SEE ALSO
clCreateContext(3clc), clGetContextInfo(3clc), clReleaseContext(3clc),
clRetainContext(3clc), clGetContextInfo(3clc), classDiagram(3clc)
AUTHORS
The Khronos Group
COPYRIGHT
Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and/or associated documentation files (the "Materials"), to deal in the Materials
without restriction, including without limitation the rights to use, copy, modify, merge,
publish, distribute, sublicense, and/or sell copies of the Materials, and to permit
persons to whom the Materials are furnished to do so, subject to the condition that this
copyright notice and permission notice shall be included in all copies or substantial
portions of the Materials.
NOTES
1. OpenCL Specification
page 56, section 4.4 - Contexts