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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-FE36E7DE-7C2C-415B-BB2F-22D9E2BE49A6" xml:lang="en"><title>Configuration Storage</title><shortdesc>The Hardware Configuration Repository (HCR) can be used

    13 to hold configuration information for DMA.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>There are two places where you may want to consider using a registry

    15 to hold information for DMA.<ol>

    16 <li id="GUID-6316ABED-967B-453F-BBB9-8F6C346C3D9F"><p>Chipset configuration </p></li>

    17 <li id="GUID-02513035-3A91-455A-8EEB-F7F914844734"><p>Channel configuration

    18 and information.</p></li>

    19 </ol></p>

    20 <section id="GUID-85868C4A-83CA-4FEE-B35E-5C168819B03D"><title>Chipset

    21 configuration</title><p>On initialization of the chipset you can store

    22 and retrieve settings in the HCR. </p><p>In the <xref href="GUID-95A33491-17AC-4F12-948E-A1352ADDA483.dita">DMA Implementation

    23 Guide</xref> there are links to a sample implementation in which no

    24 chipset configuration is required or specified.</p></section>

    25 <section id="GUID-D59E35D2-3198-43BA-91F9-153F7DCAA78A"><title>Channel

    26 configuration and information</title><p>When a client opens a channel,

    27 it specifies a cookie parameter in the <xref href="GUID-176B8E0D-0422-341B-A134-7C85432E1303.dita#GUID-176B8E0D-0422-341B-A134-7C85432E1303/GUID-934F46B3-1DF9-3870-87EE-A8E2DEF82810"><apiname>DmaChannelMgr::Open()</apiname></xref> function. This cookie is used by the DMA implementation to identify

    28 a specific channel on a specific DMA controller. This is entirely

    29 chipset and implementation specific and the client will need to know

    30 what cookie values can be used to request a channel.</p><p>One way

    31 that the implementation can communicate this information to the client

    32 is by using the Central Repository to hold a table of cookie values

    33 and matching channel identification. An alternative approach may be

    34 to use a Central Repository entry to specify the number of channels

    35 available and then the client knows the highest channel number it

    36 can request.</p><p>Again this is entirely implementation specific.

    37 In the implementation mentioned above, the repository is not used.</p></section>

    38 </conbody><related-links>

    39 <link href="GUID-14F5433A-16F4-4F01-8A7B-C8E26F46C98B.dita"><linktext>HCR

    40 Platform Service</linktext></link>

    41 </related-links></concept>