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<concept id="GUID-FE36E7DE-7C2C-415B-BB2F-22D9E2BE49A6" xml:lang="en"><title>Configuration Storage</title><shortdesc>The Hardware Configuration Repository (HCR) can be used
to hold configuration information for DMA.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>There are two places where you may want to consider using a registry
to hold information for DMA.<ol>
<li id="GUID-6316ABED-967B-453F-BBB9-8F6C346C3D9F"><p>Chipset configuration </p></li>
<li id="GUID-02513035-3A91-455A-8EEB-F7F914844734"><p>Channel configuration
and information.</p></li>
</ol></p>
<section id="GUID-85868C4A-83CA-4FEE-B35E-5C168819B03D"><title>Chipset
configuration</title><p>On initialization of the chipset you can store
and retrieve settings in the HCR. </p><p>In the <xref href="GUID-95A33491-17AC-4F12-948E-A1352ADDA483.dita">DMA Implementation
Guide</xref> there are links to a sample implementation in which no
chipset configuration is required or specified.</p></section>
<section id="GUID-D59E35D2-3198-43BA-91F9-153F7DCAA78A"><title>Channel
configuration and information</title><p>When a client opens a channel,
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
a specific channel on a specific DMA controller. This is entirely
chipset and implementation specific and the client will need to know
what cookie values can be used to request a channel.</p><p>One way
that the implementation can communicate this information to the client
is by using the Central Repository to hold a table of cookie values
and matching channel identification. An alternative approach may be
to use a Central Repository entry to specify the number of channels
available and then the client knows the highest channel number it
can request.</p><p>Again this is entirely implementation specific.
In the implementation mentioned above, the repository is not used.</p></section>
</conbody><related-links>
<link href="GUID-14F5433A-16F4-4F01-8A7B-C8E26F46C98B.dita"><linktext>HCR
Platform Service</linktext></link>
</related-links></concept>