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<concept id="GUID-0AFF5666-6BF9-5022-ADBC-5EFFA743B288" xml:lang="en"><title>ROM

Paging Guide</title><shortdesc>Describes demand paging when applied to ROM demand paging. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-D67AB531-76C8-50AE-BBA2-48FC7F47DCDD"><title>Introduction</title> <p>Demand

paging using ROM demand paging is used when the files to be paged are in the

core ROM image and not using another file system such as ROFS. </p> </section>

<section id="GUID-338FBBC7-2B90-4483-B055-2AEA23DAB479"><title>Background information</title><p> The following are useful

background information for Demand Paging using ROM demand paging:</p><ul>

<li><p>Demand Paging</p></li>

<li><p>ROM paging</p></li>

</ul> </section>

<section id="GUID-143C5BFF-AC9A-4A83-B20A-79E0A8E9B36E"><title>ROM Demand Paging features</title><p>Demand paging (using

ROM demand paging) provides the following features compared to <xref href="GUID-CE9EA167-0594-5E61-9640-6B2B63A92EA7.dita">code

paging</xref> and <xref href="GUID-2B7D04D9-98DE-5284-836D-01DB4FA8949D.dita">writable

data paging</xref> : </p><ul>

<li><p>Lower RAM overhead</p></li>

<li><p>Lower performance overhead.</p></li>

</ul> </section>

<section id="GUID-5391A3D1-A6CE-4C1A-8D42-B74A7E77E709"><title>ROM Demand Paging limitations</title><p>The following are

known limitations for Demand Paging (using ROM demand  paging) compared to

the other types of code paging: </p><ul>

<li><p>If the executable has static dependencies, then it is best to place

 these dependencies in ROFS. This is a limitation of ROFS and not ROM demand

paging.</p></li>

<li><p>This paging system can only be used with files that are stored using

 the ROM filing system. This is because ROM images using the ROM filing system

 are designed to be executed in place. </p></li>

</ul> </section>

</conbody><related-links>

<link href="GUID-D6C2202C-778C-558A-97AA-649CD6DB5E87.dita"><linktext>ROFS File

System</linktext></link>

<link href="GUID-5A71755A-E67F-5007-8C55-5B8FA65B3C04.dita"><linktext>ROM File

System</linktext></link>

<link href="GUID-D666F9A0-8BFE-5067-BC76-C3AD73587195.dita"><linktext>Composite

File System</linktext></link>

<link href="GUID-903A9956-87E2-5191-87A3-6D40797EB820.dita"><linktext>Configuring

and building a ROM</linktext></link>