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<concept id="GUID-79735B25-B4E9-5166-B87A-054080DF9122" xml:lang="en"><title>Patchable
Constants: KDiscoveryDisabledDriveList</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<codeblock id="GUID-11409345-54FC-5483-BED6-6C3AFFC19B91" xml:space="preserve"># define ECOM_PATCHDATA_KDISCOVERYDISABLEDDRIVELIST 0x0
</codeblock>
<table id="GUID-761B3924-D3BE-5568-AEFA-C1D4B4D73AF3">
<tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>
<tbody>
<row>
<entry><p>Defined in: </p> </entry>
<entry><p> <filepath>                 .../os/ossrv/lowlevellibsandfws/pluginfw/framework/frame/ecompatchdataconstantv2.cpp</filepath> </p> </entry>
</row>
<row>
<entry><p>Purpose: </p> </entry>
<entry><p>This constant lets device creators specify which drives they do
not want ECom to scan, perhaps because of a platform decision not to support
plugins (or any kind of executable binary) on certain drives e.g. MMC cards.
Note that the Read Only Internal <filepath>Z:</filepath> drive cannot be disabled. </p> <p> <codeph> KDiscoveryDisabledDriveList</codeph> is
a 32-bit integer with each bit representing a drive to disable, e.g. <codeph>0x1</codeph> disables
drive A, <codeph>0x2</codeph> disables drive B etc. Only 25 drives can be
specified (<filepath>Z:</filepath> is not allowed) therefore the 7 most significant
bits are ignored. If you want to disable scanning on drives <filepath>E:</filepath> and <filepath>K:</filepath>,
the patched value is: </p> <codeblock id="GUID-14A08DB9-FFB8-5E1C-8952-9713086A166F" xml:space="preserve">1 &lt;&lt; EDriveE | 1 &lt;&lt; EDriveK = 0x00000410.
</codeblock> <p>See <filepath>f32file.h</filepath> for the enum <codeph>TDriveNumber</codeph>. </p> </entry>
</row>
</tbody>
</tgroup>
</table>
<p>ECom uses a customized scheme to handle patchable constants. Device creators
should follow the scheme described below to set patch values: </p>
<ul>
<li id="GUID-CACEB241-0ADE-5BC1-89E9-D84E68A4A6E7"><p>Each patchable constant
is represented by a macro listed in <filepath>\epoc32\rom\include\ecompatchconstants.hby</filepath>.
The macros in the HBY file are all commented out. </p> </li>
<li id="GUID-C170972B-B993-58F5-98A3-78E92A855ABC"><p>To activate a patch
macro, uncomment the line and change the example value in the line to your
custom value. </p> </li>
</ul>
</conbody></concept>