path: root/doc/SystemTap_Beginners_Guide/en-US/Errors.xml

<?xml version='1.0'?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
]>

<chapter id="errors">
	<title>Understanding SystemTap Errors</title>

	<remark>By type - http://sourceware.org/systemtap/tutorial/node23.html</remark>
	
	<para>This chapter explains the most common errors you may encounter while using SystemTap.</para>
	
<section id="parsetype">
	<title>Parse and Semantic Errors</title>
<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
</indexterm>	
<para>These types of errors occur while SystemTap attempts to parse and
      translate the script into C, prior to being converted into a kernel
      module. For example type errors result from operations that assign invalid
      values to variables or arrays.
</para>
	
<formalpara><title>parse error: expected <replaceable>foo</replaceable>, saw <replaceable>bar</replaceable></title>
<!-- next 3 indexterms for invalid values to variables/arrays -->
<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>invalid values to variables/arrays</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>invalid values to variables/arrays</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>invalid values to variables/arrays</tertiary>
</indexterm>

<indexterm>
<primary>invalid values to variables/arrays</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>	



<!-- next 2 indexterms for grammatical script error -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>grammatical/typographical script error</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>grammatical/typographical script error</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>grammatical/typographical script error</tertiary>
</indexterm>

<indexterm>
	<primary>grammatical/typographical script error</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
<!-- next 2 indexterms for typographical script error -->

<indexterm>
<primary>typographical script error</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>


<para>The script contains a grammatical/typographical error. SystemTap detected type of construct that is incorrect, given the context of the probe.
</para>
</formalpara>

<remark>need more clarification (example) on this; could not replicate. how to
      replicate?</remark>

<para>
      The following invalid SystemTap script is missing its probe
      handlers:
</para>

<para>
<programlisting>
<xi:include parse="text" href="extras/perror.stp" xmlns:xi="http://www.w3.org/2001/XInclude" />
</programlisting>
</para>

<para>
      It results in the following error message showing that the parser was
      expecting something other than the <command>probe</command> keyword in
      column 1 of line 2:
</para>
<para>
<programlisting>
parse error: expected one of '. , ( ? ! { = +='
	saw: keyword at perror.stp:2:1
1 parse error(s).
</programlisting>
</para>

<formalpara><title>parse error: embedded code in unprivileged script</title>
<!-- next 2 indexterms for embedded code in unprivileged script -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>embedded code in unprivileged script</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>embedded code in unprivileged script</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>embedded code in unprivileged script</tertiary>
</indexterm>

<indexterm>
<primary>embedded code in unprivileged script</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>

<indexterm>
<primary>unprivileged script, embedded code in</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>

<indexterm>
<primary>unsafe embedded code in unprivileged script</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>

<para>
	The script contains unsafe embedded C code (blocks of code
	surrounded by <command>%{</command> <command>%}</command>. SystemTap
	allows you to embed C code in a script, which is useful if there are no
	tapsets to suit your purposes. However, embedded C constructs are not be
	safe; as such, SystemTap warns you with this error if such constructs
	appear in the script.
</para>
</formalpara>


<!-- next 2 indexterms for guru mode -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>guru mode</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>guru mode</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>guru mode</tertiary>
</indexterm>

<indexterm>
<primary>guru mode</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>

<para>
      If you are sure of the safety of any similar constructs in the script
      <emphasis>and</emphasis>
      are member of <command>stapdev</command> group (or have root privileges),
      run the script in "guru" mode by using the option <command>-g</command>
      (i.e. <command>stap -g <replaceable>script</replaceable></command>).
</para>

<formalpara>
	<title>semantic error: type mismatch for identifier '<replaceable>foo</replaceable>' ... string vs. long</title>
<!-- next 2 indexterms for type mismatch for identifier -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>type mismatch for identifier</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>type mismatch for identifier</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>type mismatch for identifier</tertiary>
</indexterm>

<indexterm>
<primary>type mismatch for identifier</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>

<indexterm>
<primary>identifier type mismatch</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
<para>
	The function <command><replaceable>foo</replaceable></command> in the
	script used the wrong type
	(i.e. <command>%s</command> or <command>%d</command>). This error will
	present itself in <xref linkend="errorvariable"/>, because the function
	<command>execname()</command> returns a string the format specifier
	should be a <command>%s</command>, not <command>%d</command>. 
</para>
</formalpara>

<example id="errorvariable">
	<title>error-variable.stp</title>
<programlisting>
probe syscall.open
{
  printf ("%d(%d) open\n", execname(), pid())
}
</programlisting>
</example>

<formalpara>
	<title>semantic error: unresolved type for identifier '<replaceable>foo</replaceable>'</title>
<!-- next 2 indexterms for unresolved type for identifier -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>unresolved type for identifier</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>unresolved type for identifier</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>unresolved type for identifier</tertiary>
</indexterm>

<indexterm>
<primary>unresolved type for identifier</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>	
<para>The identifier (e.g. a variable) was used, but no type (integer or
	string) could be determined. This occurs, for instance, if you use a
	variable in a <command>printf</command> statement while
	the script never assigns a value to the variable.</para>
</formalpara>

<formalpara>
	<title>semantic error: Expecting symbol or array index expression</title>
<!-- next 2 indexterms for expected symbol/array index expression -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>expected symbol/array index expression</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>expected symbol/array index expression</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>expected symbol/array index expression</tertiary>
</indexterm>

<indexterm>
<primary>expected symbol/array index expression</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>	
	
<para>
	SystemTap could not assign a value to a variable or to a location in an
	array. The destination for the assignment is not a valid destination.
	The following example code would generate this error:
</para>
</formalpara>
<para>
<programlisting>
<xi:include parse="text" href="extras/werror.stp" xmlns:xi="http://www.w3.org/2001/XInclude" />
</programlisting>
</para>

<formalpara>
	<title>while searching for arity <replaceable>N</replaceable> function, semantic error: unresolved function call</title>
<!-- next 2 indexterms for unresolved function call -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>unresolved function call</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>unresolved function call</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>unresolved function call</tertiary>
</indexterm>

<indexterm>
<primary>unresolved function call</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>	

<indexterm>
<primary>function call (unresolved)</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
<para>A function call or array index expression in the script used an invalid
	number of arguments/parameters. In SystemTap
	<firstterm>arity</firstterm> can either refer to the number of indices
	for an array, or the number of parameters to a function.</para>
</formalpara>

<formalpara>
	<title>semantic error: array locals not supported, missing global declaration?</title>
	
<!-- next 2 indexterms for non-global arrays -->
<indexterm>
<primary>array locals not supported</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>non-global arrays</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>non-global arrays</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>non-global arrays</tertiary>
</indexterm>

<indexterm>
<primary>non-global arrays</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
	<para>The script used an array operation without declaring the array as
	a global variable (global variables can be declared after their use in
	Systemtap scripts). Similar messages appear if an array is used, but with inconsistent arities.</para>
</formalpara>

<formalpara>
	<title>semantic error: variable ’<replaceable>foo</replaceable>’ modified during ’foreach’ iteration</title>
<!-- next 2 indexterms for variable modified during 'foreach' -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>variable modified during 'foreach'</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>variable modified during 'foreach'</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>variable modified during 'foreach'</tertiary>
</indexterm>

<indexterm>
<primary>variable modified during 'foreach'</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
	<para>The array <literal>foo</literal> is being modifed (being assigned to or deleted from) within an active <command>foreach</command> loop. This error also displays if an operation within the script performs a function call within the <command>foreach</command> loop.</para>
</formalpara>

<formalpara>
	<title>semantic error: probe point mismatch at position <replaceable>N</replaceable>, while resolving probe point <replaceable>foo</replaceable></title>


<!-- next 2 indexterms for probe mismatch -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>probe mismatch</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>probe mismatch</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>probe mismatch</tertiary>
</indexterm>

<indexterm>
<primary>probe mismatch</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
	<para>SystemTap did not understand what the event or SystemTap function
	<computeroutput><replaceable>foo</replaceable></computeroutput> refers
	to. This usually means that SystemTap could not find a match for
	<computeroutput><replaceable>foo</replaceable></computeroutput> in the
	tapset library. The <replaceable>N</replaceable> refers to the 
	line and column of 
	the error.</para>
</formalpara>	
	
<remark>how to explain N in previous? "The divergence from the “tree” of probe point namespace is at position N (starting with zero at left)." (from tutorial) </remark>

<formalpara>
	<title>semantic error: no match for probe point, while resolving probe point <replaceable>foo</replaceable></title>


<!-- next 2 indexterms for no match for probe point -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>no match for probe point</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>no match for probe point</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>no match for probe point</tertiary>
</indexterm>

<indexterm>
<primary>no match for probe point</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>

<indexterm>
<primary>probe point (no match for)</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
	<para>The events / handler function <computeroutput><replaceable>foo</replaceable></computeroutput> could not be resolved altogether, for a variety of reasons. This error occurs when the script contains the event <command>kernel.function("<replaceable>blah</replaceable>")</command>, and <command><replaceable>blah</replaceable></command> does not exist. In some cases, the error could also mean the script contains an invalid kernel file name or source line number.</para>
</formalpara>

<formalpara>
	<title>semantic error: unresolved target-symbol expression</title>
<!-- next 2 indexterms for unresolved target-symbol expression -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>unresolved target-symbol expression</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>unresolved target-symbol expression</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>unresolved target-symbol expression</tertiary>
</indexterm>

<indexterm>
<primary>unresolved target-symbol expression</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>

<indexterm>
<primary>target-symbol expression, unresolved</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>
	<para>A handler in the script references a target variable, but the
	value of the variable could not be resolved. This error could also mean
	that a handler is referencing a target variable that is not valid
	in the context when it was referenced. This may be a result of compiler
        optimization of the generated code.</para>
</formalpara>

<formalpara>
	<title>semantic error: libdwfl failure </title>
	
<!-- next 2 indexterms for libdwfl failure -->

<indexterm>
<primary>understanding SystemTap errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>libdwfl failure</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>parse/semantics error</secondary>
<tertiary>libdwfl failure</tertiary>
</indexterm>

<indexterm>
<primary>parse/semantics error</primary>
<secondary>understanding SystemTap errors</secondary>
<tertiary>libdwfl failure</tertiary>
</indexterm>

<indexterm>
<primary>libdwfl failure</primary>
<secondary>parse/semantics error</secondary>
<tertiary>understanding SystemTap errors</tertiary>
</indexterm>	
	<para>There was a problem processing the debugging information. In most
	cases, this error results from the installation of a
	<filename>kernel-debuginfo</filename> RPM whose version does not match
	the probed kernel exactly. The installed <filename>kernel-debuginfo</filename> RPM itself may have some consistency / correctness problems.</para>
</formalpara>

<formalpara>
	<title>semantic error: cannot find <replaceable>foo</replaceable> debuginfo</title>
	<para>SystemTap could not find a suitable <filename>kernel-debuginfo</filename> at all. </para>
</formalpara>
<!--
<formalpara>
	<title></title>
<para></para>
</formalpara>
-->

</section>	

<section id="runtimeerror">
	<title>Run Time Errors and Warnings</title>
<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
</indexterm>
	

<para>
		Runtime errors and warnings occur when the SystemTap
		instrumentation has been installed and is collecting data on
		the system.
	</para>

<formalpara><title>WARNING: Number of errors: <replaceable>N</replaceable>, skipped probes: <replaceable>M</replaceable></title>
<!-- next 2 indexterms for number of errors: N, skipped probes: M -->

<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>number of errors: N, skipped probes: M</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>number of errors: N, skipped probes: M</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>number of errors: N, skipped probes: M</tertiary>
</indexterm>

<indexterm>
<primary>number of errors: N, skipped probes: M</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>
<para>
	Errors and/or skipped probes occurred during this run. Both 
	<replaceable>N</replaceable> and <replaceable>M</replaceable> are
	the counts of the number of probes that were not executed due to
	conditions such as too much time required to execute event handlers over
	an interval of time.
</para>
</formalpara>

<formalpara><title>division by 0</title>
<!-- next 2 indexterms for division by 0 -->

<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>division by 0</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>division by 0</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>division by 0</tertiary>
</indexterm>

<indexterm>
<primary>division by 0</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>

<indexterm>
<primary>invalid division</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>

<para>
	The script code performed an invalid division.
</para>
</formalpara>

<formalpara><title>aggregate element not found</title>
<!-- next 2 indexterms for aggregate element not found -->

<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>aggregate element not found</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>aggregate element not found</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>aggregate element not found</tertiary>
</indexterm>

<indexterm>
<primary>aggregate element not found</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>
<para>
	An statistics extractor function other than <command>@count</command>
	was invoked on an aggregate that has not had any values accumulated yet.
	This is similar to a division by zero.
</para>
</formalpara>

<formalpara><title>aggregation overflow</title>
<!-- next 3 indexterms for aggregation overflow -->
<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>aggregation overflow</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>aggregation overflow</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>aggregation overflow</tertiary>
</indexterm>

<indexterm>
<primary>aggregation overflow</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>
<indexterm>
<primary>overflow of aggregation</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>	
	
<para>
An array containing aggregate values contains too many distinct key pairs at this time.
</para>	
<!--<para>
    An array containing aggregate values contains too many distinct key tuples at this time.
</para>-->
</formalpara>


<formalpara><title>MAXNESTING exceeded</title>
<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>MAXNESTING exceeded</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>MAXNESTING exceeded</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>MAXNESTING exceeded</tertiary>
</indexterm>

<indexterm>
<primary>MAXNESTING exceeded</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>

<indexterm>
<primary>exceeded MAXNESTING</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>

<para>
	Too many levels of function call nesting were attempted.
	The default nesting of function calls allowed is 10.
</para>
</formalpara>

<formalpara><title>MAXACTION exceeded</title>
<!-- next 2 indexterms for MAXACTION exceeded -->

<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>MAXACTION exceeded</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>MAXACTION exceeded</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>MAXACTION exceeded</tertiary>
</indexterm>

<indexterm>
<primary>MAXACTION exceeded</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>	

<indexterm>
	<primary>exceeded MAXACTION</primary>
	<secondary>runtime errors/warnings</secondary>
	<tertiary>understainding SystemTap errors</tertiary>
</indexterm>
<para>
	The probe handler attempted to execute too many statements in the
	probe handler. The default number of actions allow in a probe handler
	is 1000.
</para>
</formalpara>

<formalpara><title>kernel/user string copy fault at
      <replaceable>ADDR</replaceable></title>
<!-- next 2 indexterms for copy fault -->

<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>copy fault</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>copy fault</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>copy fault</tertiary>
</indexterm>

<indexterm>
<primary>copy fault</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>
<para>
	The probe handler attempted to copy a string from kernel or
	user space at an invalid address (<replaceable>ADDR</replaceable>).
</para>
</formalpara>

<formalpara><title>pointer dereference fault</title>


<!-- next 2 indexterms for pointer dereference fault -->

<indexterm>
<primary>understainding SystemTap errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>pointer dereference fault</tertiary>
</indexterm>

<indexterm>
<primary>errors</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>pointer dereference fault</tertiary>
</indexterm>

<indexterm>
<primary>runtime errors/warnings</primary>
<secondary>understainding SystemTap errors</secondary>
<tertiary>pointer dereference fault</tertiary>
</indexterm>

<indexterm>
<primary>pointer dereference fault</primary>
<secondary>runtime errors/warnings</secondary>
<tertiary>understainding SystemTap errors</tertiary>
</indexterm>	
<para>
	There was a fault encountered during a pointer
	dereference operation such as a target variable evaluation.
</para>
</formalpara>

</section>

</chapter>