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AIX 5L Problem Determination - IBM Redbooks

AIX 5L Problem Determination - IBM Redbooks

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Using crash, you can examine:<br />

► Addresses and symbols<br />

► Kernel stack traceback<br />

► Kernel extensions<br />

► The process table<br />

► The thread table<br />

► The file table<br />

► The inode table<br />

► System registers<br />

In addition to the items listed, you can use crash to look at anything else<br />

contained in the kernel memory.<br />

What the kernel is<br />

The kernel is the program that controls and protects system resources. It runs in<br />

privileged mode. It operates directly with the hardware. The major functions of<br />

the kernel are:<br />

► Creation and deletion of processes/threads<br />

► CPU scheduling<br />

► Memory management<br />

► Device management<br />

► Synchronization and communication tools for processes<br />

In contrast to a user program, which creates a core dump and halts. If the kernel<br />

has an error the machine will fail.<br />

The crash command is used to debug these kernel problems.<br />

Examining a system dump<br />

The crash command needs a kernel /unix file to match the dump file under<br />

analysis. For example:<br />

itsosrv1:/dumptest> crash dumpfile unix<br />

><br />

If no kernel file is specified, the default is /unix.<br />

itsosrv1:/dumptest> crash dumpfile<br />

Using /unix as the default namelist file.<br />

><br />

84 <strong>IBM</strong> ^ Certification Study Guide - <strong>AIX</strong> <strong>5L</strong> <strong>Problem</strong> <strong>Determination</strong> Tools and Techniques

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