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<?xml-stylesheet type="text/xsl" href="https://community.arm.com/utility/feedstylesheets/rss.xsl" media="screen"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" xmlns:wfw="http://wellformedweb.org/CommentAPI/"><channel><title>How to disable the branch prediction on armv8</title><link>https://community.arm.com/developer/ip-products/processors/f/cortex-a-forum/48050/how-to-disable-the-branch-prediction-on-armv8</link><description> Hello, 
 I am working with ARMV8 Cortex A72 architecture, i want to know can i turn off branch prediction? and how can i do it? 
 best regards, </description><dc:language>en-US</dc:language><generator>Telligent Community 10</generator><item><title>RE: How to disable the branch prediction on armv8</title><link>https://community.arm.com/thread/168664?ContentTypeID=1</link><pubDate>Mon, 16 Nov 2020 13:06:10 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:117e8df3-7a70-45ca-8457-7c175b77ecbe</guid><dc:creator>vstehle</dc:creator><description>&lt;p&gt;Hi &lt;a href="/members/rifakst" class="internal-link view-user-profile"&gt;Rifakst&lt;/a&gt;,&lt;/p&gt;
&lt;p&gt;The&amp;nbsp;&lt;a href="https://developer.arm.com/documentation/100095/0003/system-control/aarch64-register-descriptions/cpu-auxiliary-control-register--el1"&gt;CPU Auxiliary Control Register (CPUACTLR_EL1)&lt;/a&gt;&amp;nbsp;of the Cortex-A72 provides some level of control over the branch prediction:&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;Bit 34 disables static branch predictor.&lt;/p&gt;
&lt;p&gt;Bit 33 d&lt;span&gt;isables main prediction suppression at target fetch of microBTB.&lt;/span&gt;&lt;/p&gt;
&lt;p&gt;Bit 4 disables indirect predictor.&lt;/p&gt;
&lt;p&gt;Bit 3 disables micro BTB.&lt;/p&gt;
&lt;p&gt;&lt;a href="https://developer.arm.com/documentation/100095/0003/level-1-memory-system/program-flow-prediction"&gt;The section Program flow prediction of A72 TRM&lt;/a&gt;&amp;nbsp;gives some details about each function.&lt;/p&gt;
&lt;p&gt;Best regards,&lt;/p&gt;
&lt;p&gt;Vincent.&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: How to disable the branch prediction in armv8</title><link>https://community.arm.com/thread/168652?ContentTypeID=1</link><pubDate>Sun, 15 Nov 2020 12:01:11 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:60caa2c9-74ca-444d-b769-09d1bc34a665</guid><dc:creator>42Bastian Schick</dc:creator><description>&lt;p&gt;I guess it can&amp;#39;t (ARM 100095_0003_06_en):&lt;br /&gt;&lt;em&gt;6.5.5&amp;nbsp; Enabling program flow prediction&lt;br /&gt;&amp;nbsp;&lt;br /&gt;Program flow prediction is always enabled and no programming is required to take advantage of&lt;br /&gt;program flow prediction.&lt;br /&gt;When reset, the processor:&lt;br /&gt;&amp;bull; Invalidates the BTB.&lt;br /&gt;&amp;bull; Resets the GHB and indirect predictor to a known state.&lt;br /&gt;No software intervention is required to prepare the prediction logic before enabling program flow&lt;br /&gt;prediction.&lt;/em&gt;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item></channel></rss>