sdk/2.0/docs/man/cl_khr_initialize_memory.xml

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<refentry>
    <refentryinfo>
        <keywordset>
            <keyword>cl_khr_initialize_memory</keyword>
        </keywordset>
    </refentryinfo>

    <refmeta>
        <refentrytitle>cl_khr_initialize_memory</refentrytitle>

        <refmiscinfo>
            <copyright>
                <year>2007-2013</year>
                <holder>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,
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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.</holder>
            </copyright>
        </refmiscinfo>
        <manvolnum>3</manvolnum>
    </refmeta>

<!-- ================================ SYNOPSIS -->

    <refnamediv id="cl_khr_initialize_memory">
        <refname>cl_khr_initialize_memory</refname>

        <refpurpose>
            Extension adds support for initializing local and private memory before a kernel begins execution.
        </refpurpose>
    </refnamediv>

    <!-- ALTERNATIVE SYNTAX SYNOPSIS (NON-FUNCTION) -->

    <refsect2 id="synopsis">
        <title>
        </title>

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            <tgroup cols="1" align="left" colsep="0" rowsep="0">
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                        <entry>
#pragma OPENCL EXTENSION cl_khr_initialize_memory : enable
                        </entry>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
    </refsect2>

<!-- ================================ DESCRIPTION  -->

    <refsect1 id="description"><title>Description</title>
        <para>
            Memory is allocated in various forms in OpenCL both explicitly (global memory) or implicitly 
            (local, private memory). This allocation so far does not provide a straightforward mechanism to 
            initialize the memory on allocation. In other words what is lacking is the equivalent of calloc for 
            the currently supported malloc like capability. This functionality is useful for a variety of 
            reasons including ease of debugging, application controlled limiting of visibility to previous 
            contents of memory and in some cases, optimization.
        </para>

        <para>
            This extension adds support for initializing local and private memory before a kernel begins 
            execution. This extension name is <code>cl_khr_initialize_memory</code>.
        </para>

        <para>
            Add a new context property to table 4.5 in section 4.4 
            (see <citerefentry><refentrytitle>clCreateContext</refentrytitle></citerefentry>):
        </para>

        <informaltable frame="all">
        <tgroup cols="3" align="left" colsep="1" rowsep="1">
            <colspec colname="col1" colnum="1" />
            <colspec colname="col2" colnum="2" />
            <colspec colname="col3" colnum="3" />

            <thead>
                <row>
                    <entry>cl_context_properties enum</entry>
                    <entry>Property value</entry>
                    <entry>Description</entry>
                </row>
            </thead>

            <tbody>
                <row>
                    <entry><constant>CL_CONTEXT_MEMORY_-
INITIALIZE_KHR</constant></entry>
                    <entry><type>cl_context_memory_-
initialize_khr</type></entry>
                    <entry>
                        <para>
                            Describes which memory types for the 
                            context must be initialized. This is a 
                            bit-field, where the following values are 
                            currently supported:
                        </para>

                        <para>
                            <constant>CL_CONTEXT_MEMORY_INITIALIZE_LOCAL_KHR</constant> – Initialize local memory 
                            to zeros.
                        </para>

                        <para>
                            <constant>CL_CONTEXT_MEMORY_INITIALIZE_PRIVATE_KHR</constant> – Initialize private 
                            memory to zeros.
                        </para>
                    </entry>
                </row>
            </tbody>

        </tgroup>
        </informaltable>

        <para>
            Updates to section 6.9 –Restrictions:
        </para>

        <para>
            <!-- The spec rev. 19 shows this constant with no underscores -->
            If the context is created with 
            <constant>CL CONTEXT MEMORY INITIALIZE KHR</constant>, appropriate memory 
            locations as specified by the bit-field is 
            initialized with zeroes, prior to the start of execution of 
            any kernel. The driver chooses when, prior to 
            kernel execution, the initialization of local and/or
            private memory is performed. The only requirement 
            is there should be no values set from outside 
            the context, which can be read during a kernel execution.
        </para>

    </refsect1>


<!-- ================================ EXAMPLE  -->
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            Example
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                        <entry>
                            Example goes here - it will be set in "code" type with white space preserved.
                        </entry>
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<!-- ================================ SPECIFICATION  -->
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            <olink uri="cl_khr_initialize_memory">OpenCL Specification</olink>
        </para>
    </refsect1>

<!-- ================================ ALSO SEE  -->

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    </refsect1>
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<!-- ============================== COPYRIGHT -->
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<!-- 24-Dec-2013, rev. 19 -->
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