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| <h4 class="subsection">21.1.1 BSD libkvm Interface</h4> |
| |
| <p><a name="index-libkvm-1439"></a><a name="index-kernel-memory-image-1440"></a><a name="index-kernel-crash-dump-1441"></a> |
| BSD-derived systems (FreeBSD/NetBSD/OpenBSD) have a kernel memory |
| interface that provides a uniform interface for accessing kernel virtual |
| memory images, including live systems and crash dumps. <span class="sc">gdb</span> |
| uses this interface to allow you to debug live kernels and kernel crash |
| dumps on many native BSD configurations. This is implemented as a |
| special <code>kvm</code> debugging target. For debugging a live system, load |
| the currently running kernel into <span class="sc">gdb</span> and connect to the |
| <code>kvm</code> target: |
| |
| <pre class="smallexample"> (gdb) <b>target kvm</b> |
| </pre> |
| <p>For debugging crash dumps, provide the file name of the crash dump as an |
| argument: |
| |
| <pre class="smallexample"> (gdb) <b>target kvm /var/crash/bsd.0</b> |
| </pre> |
| <p>Once connected to the <code>kvm</code> target, the following commands are |
| available: |
| |
| |
| <a name="index-kvm-1442"></a> |
| <dl><dt><code>kvm pcb</code><dd>Set current context from the <dfn>Process Control Block</dfn> (PCB) address. |
| |
| <br><dt><code>kvm proc</code><dd>Set current context from proc address. This command isn't available on |
| modern FreeBSD systems. |
| </dl> |
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