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285 lines
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XML
285 lines
12 KiB
XML
<appendix xmlns="http://docbook.org/ns/docbook"
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xmlns:xl="http://www.w3.org/1999/xlink"
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xml:id="dbdoclet.50569381_46906"
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version="5.0"
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xml:lang="en">
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<title>EEH Error Processing</title>
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<para>This appendix describes the architectural intent for EEH error processing.
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This appendix does not attempt to illustrate all possible scenarios, and other
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implementations are possible.</para>
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<section xml:id="dbdoclet.50569381_11923">
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<title>General Scenarios</title>
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<para>In general, the device driver recovery consists of issuing an
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<emphasis>ibm,read-slot-reset-state2</emphasis> call prior to doing any recovery
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to determine if (1) the IOA is in the MMIO Stopped and DMA Stopped state (that is,
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that an error has occurred which has put it into this state), and (2) whether or
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not the PE has been reset by the platform in the process of entering the MMIO
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Stopped and DMA Stopped state, and then doing one of the following:</para>
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<orderedlist>
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<listitem>
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<para>Simplest approach: </para>
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<itemizedlist>
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<listitem>
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<para>Reset the PE</para>
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</listitem>
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<listitem>
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<para>Reconfigure the PE</para>
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</listitem>
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</itemizedlist>
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</listitem>
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<listitem xml:id="dbdoclet.50569381_39262">
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<para>Most general approach (detailed more in <xref linkend="dbdoclet.50569381_38095"/>): </para>
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<itemizedlist>
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<listitem>
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<para>Release the PE for <emphasis>Load</emphasis> /<emphasis>Store</emphasis></para>
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</listitem>
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<listitem>
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<para>Issue <emphasis>Load</emphasis> /<emphasis> Store</emphasis> instructions t
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o get any desired state information from the IOA</para>
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</listitem>
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<listitem>
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<para>Call the <emphasis>ibm,slot-error-detail</emphasis> RTAS call to get the
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platform error information</para>
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</listitem>
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<listitem>
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<para>Log the error information</para>
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</listitem>
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<listitem>
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<para>Reset the PE</para>
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</listitem>
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<listitem>
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<para>Reconfigure the PE</para>
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</listitem>
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</itemizedlist>
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</listitem>
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<listitem>
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<para>Most robust (no reset unless necessary): </para>
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<itemizedlist>
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<listitem>
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<para>Release the PE for <emphasis>Load</emphasis> /<emphasis>Store</emphasis></para>
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</listitem>
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<listitem>
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<para>Issue <emphasis> Load</emphasis> /<emphasis> Store</emphasis> instructions
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to get any desired state information from the IOA</para>
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</listitem>
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<listitem>
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<para>Call the <emphasis> ibm,slot-error-detail</emphasis> RTAS call to get the
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platform error information</para>
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</listitem>
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<listitem>
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<para>Log the error information</para>
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</listitem>
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<listitem>
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<para>Device driver does IOA cleanup</para>
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</listitem>
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<listitem>
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<para>Release the PE for DMA and restart operations (no reset) </para>
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</listitem>
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</itemizedlist>
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</listitem>
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</orderedlist>
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<para>In any scenario, after several retries of a recoverable operation, the OS
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may determine that further recovery efforts should cease. In such a case,
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calling <emphasis>ibm,slot-error-detail</emphasis> with <emphasis>Function</emphasis> 2
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(Permanent Error), in addition to returning error information, marks that the PE is
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no longer accessible due to previous errors.</para>
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</section>
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<section xml:id="dbdoclet.50569381_38095">
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<title>More Detail on the Most General Approach</title>
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<para>The following gives a more detailed look at scenario #<xref linkend="dbdoclet.50569381_39262"/>
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in <xref linkend="dbdoclet.50569381_11923"/>. This will be broken up into two groups of operations:
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error logging and error recovery.</para>
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<para>These scenarios assume that:</para>
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<orderedlist>
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<listitem>
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<para>The <emphasis> ibm,configure-pe</emphasis> RTAS call is implemented.</para>
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</listitem>
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<listitem>
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<para>The attempts at recovery stop when Max_Retries_Exceeded is true.</para>
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</listitem>
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</orderedlist>
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<section>
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<title>Error Logging</title>
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<orderedlist>
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<listitem>
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<para>If the device driver is going to capture internal IOA-specific information
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as a part of the error logging process or if the IOA controlled by the device driver
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requires a longer wait after reset than the normal PCI specified minimum wait time,
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then the device driver determines whether its IOA has been reset as a result of entering
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EEH Stopped State, by looking at the <emphasis>PE Recovery Info</emphasis> output of
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the <emphasis>ibm,read-slot-reset-state2</emphasis> RTAS call.</para>
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</listitem>
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<listitem>
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<para>The OS or device driver insures that all MMIOs to the IOA(s) in the PE are finished.</para>
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</listitem>
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<listitem>
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<para>If the IOA requires longer wait after reset times than the specified minimum,
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and the PE was reset (see step #1) as a result of the EEH event, then wait the
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additional necessary time before continuing.</para>
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</listitem>
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<listitem xml:id="dbdoclet.50569381_59303">
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<para>The OS or device driver
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enables PE MMIOs by calling the <emphasis>ibm,set-eeh-option</emphasis> RTAS call
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with <emphasis>Function</emphasis> 2. </para>
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</listitem>
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<listitem>
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<para>The OS or device driver calls the <emphasis>ibm,configure-pe</emphasis> RTAS call. </para>
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<orderedlist numeration="loweralpha">
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<listitem>
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<para>If the PCI fabric does not need configuring (the PE was not reset previous to the
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call or was reset but was previously configured with <emphasis>ibm,configure-pe</emphasis> ),
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then the call returns without doing anything, otherwise it attempts to configure
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the fabric up to but not including the endpoint IOA configuration registers.</para>
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</listitem>
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<listitem>
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<para>If an EEH event occurs as a result of probing during the
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<emphasis>ibm,configure-pe</emphasis> RTAS call that results in a
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reset of the PE, the PE will be returned in the PE state of 2. Software
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does not necessarily need to check this on return from the call. The case
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where this occurs is expected to be rare, and probably signals a non-transient error.
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In this case the software can continue on with the recovery phase of the EEH processing,
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and will eventually hit the same EEH event on further processing.</para>
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</listitem>
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</orderedlist>
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</listitem>
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<listitem xml:id="dbdoclet.50569381_74560">
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<para>If the PE was
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reset (see step #1) as a result of the EEH event, then if the device driver is
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going to gather IOA-specific information for logging, it needs to finish the
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configuration of the IOA PCI configuration registers, by restoring the PCI
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configuration space registers of the IOA(s) in the PE (for example, BARs,
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Memory Space Enable, etc.). </para>
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</listitem>
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<listitem xml:id="dbdoclet.50569381_29191">
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<para>If desired, the
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device driver gathers IOA-specific information via MMIOs, by doing MMIOs to its IOA.</para>
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</listitem>
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<listitem>
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<para>The OS or device driver calls <emphasis>ibm,slot-error-detail</emphasis> .
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Any data captured in step #<xref linkend="dbdoclet.50569381_29191"/> is passed in the
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call. Note that maximum amount of data will be captured in some cases only when the
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<emphasis>ibm,slot-error-detail</emphasis> call is made with PE not in the MMIO Stopped
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State (as it should be in step #<xref linkend="dbdoclet.50569381_59303"/>). </para>
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<orderedlist numeration="loweralpha">
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<listitem>
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<para>If Max_Retries_Exceeded is true, then call <emphasis>ibm,slot-error-detail</emphasis>
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with <emphasis> Function</emphasis> 2 (Permanent Error).</para>
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</listitem>
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<listitem>
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<para>If Max_Retries_Exceeded is not true, then call <emphasis>ibm,slot-error-detail</emphasis>
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with <emphasis>Function</emphasis> 1(Temporary Error).</para>
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</listitem>
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</orderedlist>
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</listitem>
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<listitem>
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<para>The <emphasis>ibm,slot-error-detail</emphasis> RTAS call captures whatever
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PCI config space registers it can between the configuration address passed in the call
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and the system (PHB), and including at the configuration address and at the PHB, and
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returns them along with the device specific data in an error log in the return information
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from the call. This call may encounter another EEH event, in which case it returns what
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information it can in the call, with a <emphasis>Status</emphasis> of 0 (Success).</para>
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</listitem>
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<listitem>
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<para>The OS or device driver logs the log entry returned from the
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<emphasis>ibm,slot-error-detail</emphasis> RTAS call.</para>
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</listitem>
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<listitem>
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<para>If Max_Retries_Exceeded is not true, then the next step is PE Recovery,
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otherwise stop and mark the IOA(s) in the PE as unusable.</para>
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</listitem>
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</orderedlist>
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</section>
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<section>
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<title>PE Recovery</title>
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<orderedlist>
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<listitem>
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<para>OS or device driver does a PE reset sequence. Note that this step is
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required even if the PE was reset as a result of the initial EEH event, because
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the error logging steps (for example, the <emphasis>ibm,configure-pe</emphasis>
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or <emphasis> ibm,slot-error-detail</emphasis> calls) could have encountered
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another EEH event. </para>
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<orderedlist numeration="loweralpha">
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<listitem>
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<para>The device driver or OS calls <emphasis>ibm,set-slot-reset</emphasis> with
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<emphasis>Function</emphasis> 1 or 3 to activate the reset.</para>
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</listitem>
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<listitem>
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<para>The minimum reset active time is waited.</para>
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</listitem>
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<listitem>
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<para>The device driver or OS calls <emphasis>ibm,set-slot-reset</emphasis> with
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<emphasis>Function</emphasis> 0 to deactivate the reset.</para>
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</listitem>
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<listitem>
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<para>The minimum reset inactive to first configuration cycles is waited.
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If the IOA requires more than the standard PCI specified time, then wait that
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longer time, instead.</para>
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</listitem>
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</orderedlist>
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</listitem>
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<listitem>
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<para>The OS or device driver calls <emphasis>ibm,configure-pe.</emphasis>
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<note><para>If an EEH event occurs as a result of probing
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during the <emphasis>ibm,configure-pe</emphasis> RTAS call that results in a reset
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of the PE, the PE will be returned in the PE state of 2. Software does not necessarily
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need to check this on return from the call. The case where this occurs is expected to
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be rare, and probably signals a non-transient error. In this case the software can
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continue on with the recovery phase of the EEH processing, and will eventually hit
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the same EEH event on further processing.</para></note>
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</para>
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</listitem>
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<listitem>
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<para>The device driver restores the PCI configuration spaces of the IOA(s) in the PE.</para>
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</listitem>
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<listitem>
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<para>The device driver initializes the IOA for operations.</para>
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</listitem>
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</orderedlist>
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</section>
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</section>
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</appendix>
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