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<concept id="GUID-4993AF8E-28C3-54BA-8D27-D86E05D39CFD" xml:lang="en"><title>Crash

Logger Technology</title><shortdesc>The Crash Logger contains a logger program that stores system state

information when a crash occurs, and a reader application that can be used

later to get this information</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-060E1937-9BB9-5A81-A1FA-7EAEA04B9DEF"><title>The

crash logger</title> <p>When the kernel crashes, control is handed to the

crash logger. It tries to read as much state information as it can reasonably

find, and dumps it to a pre-reserved location in permanent storage flash storage). </p> <p>Support

exists for dumping information to <i>nor</i> flash and <i>nand</i> flash.

The crash logger must have its own drivers to do this, as it cannot be assumed

that any specific part of the kernel is operating correctly in these circumstances.

These drivers are essentially simplified versions of the standard drivers. </p> <p>All

monitoring functionality, crash logging and crash debugging is placed in kernel

extensions. Functionality can be enabled or disabled by placing the appropriate

kernel extensions into ROM at ROM build time. </p> <p>To support both crash

logging and debugging without duplicating code, a common module, <filepath>exmoncommon.dll</filepath>,

has been created. This extension contains all of the generic monitoring code,

and supports features such as dumping registers, thread stacks and object

containers and is responsible for registering with the kernel’s crash monitor

entry point: </p> <codeblock id="GUID-F1EF54CF-614D-5459-ABA1-07F5E9D3969E" xml:space="preserve">Epoc::SetMonitorEntryPoint()</codeblock> <p>This

extension must be placed in ROM before either of the two monitoring extensions,

as they both rely on its functionality. As <filepath>exmoncommon.dll</filepath> depends

on the underlying memory model, it is built from the Variant. </p> <p>After

the common monitoring code registers itself with the kernel, further debugging

extensions may register with the common code. These extensions are called

when the kernel fails, in the order that they register. The maximum number

of extensions currently supported is nine though only two- the interactive

debugger, and the non-interactive crash logger are provided. However, this

is an arbitrary limit set by the macro definition <codeblock xml:space="preserve">MONITOR_MAXCOUNT</codeblock> in

the file <filepath>E32\include\kernel\monitor.h</filepath>, and can be increased

given sensible use cases. </p> <ul>

<li id="GUID-75C55DE2-982C-59E2-8A93-43457B687165"><p> <filepath>exmondebug.dll</filepath> is

the traditional interactive debugger. </p> </li>

<li id="GUID-12933627-FEBC-5D1A-9573-81F15FEDA328"><p> <filepath>exmonlog.dll</filepath> is

the crash logger. </p> </li>

</ul> <p>These DLLs are also built from the Variant. In the case of the crash

logger, two separate <filepath>.mmp</filepath> files exist: </p> <ul>

<li id="GUID-88D7A132-143A-519A-8645-FAA11D484FC7"><p>one for NAND flash,

building <filepath>exmonlognand.dll</filepath>  </p> </li>

<li id="GUID-EE02A14E-9E19-516D-93F9-B6590736D71C"><p>one for NOR flash, building <filepath>exmonlognor.dll</filepath>  </p> </li>

</ul> <p>The rombuild scripts ensure that the crash logger for only one type

of flash is placed into the ROM, and named as <filepath>exmonlog.dll</filepath>. </p> </section>

<section id="GUID-7CAFA8C9-597C-5F20-AB15-22FFC7EFA203"><title>The crash reader</title> <p>At

the next system boot, the crash reader application uses the normal system

flash drivers to read the crash log from the reserved non-filesystem (non-uservisible)

flash area, and to write it into the user-visible file system. </p> <p>The

output file from the crash reader is a text file, or a compressed <filepath>GZIP-compatible</filepath> file. </p> <p>The

crash reader application is called <filepath>crashread.exe</filepath>, which

is built from <filepath>e32utils\crashread\crashread.mmp</filepath>. </p> </section>

</conbody></concept>