Debugging Qemu - Revision history

Tiziano: /* Generate core dumps */

2014-06-12T13:18:55Z

Generate core dumps

← Older revision		Revision as of 15:18, 12 June 2014
Line 61:		Line 61:
	</source>		</source>

	... after that, all Qemu processes will generate a (unique) core dump file in /var/virtualization/core-dumps in case they crash		... after that, all newly started Qemu processes will generate a (unique) core dump file in <code>/var/virtualization/core-dumps</code> in case they crash


	[[Category:Snippets]]		[[Category:Snippets]]

Tiziano at 13:15, 12 June 2014

2014-06-12T13:15:43Z

@@ Line 1: / Line 1: @@
 Sometimes you must be able to analyse Qemu more in-depth than the log files allow to.
 For this, one can attach a [https://www.gnu.org/software/gdb/ GDB] instance to a running Qemu process as long as it is started with the <code>-s</code> option.
@@ Line 46: / Line 48: @@
 Continuing.
 </pre>
 [[Category:Snippets]]

Tiziano at 14:14, 5 June 2014

2014-06-05T14:14:09Z

← Older revision		Revision as of 16:14, 5 June 2014
Line 1:		Line 1:
	Sometimes you must be able to analyse Qemu more in-depth than the log files allow to.		Sometimes you must be able to analyse Qemu more in-depth than the log files allow to.

	For this, one can attach a ~~<code>~~gdb</~~code>~~ instance to a running Qemu process if it is started with the <code>-s</code> option.		For this, one can attach a [https://www.gnu.org/software/gdb/ GDB] instance to a running Qemu process as long as it is started with the <code>-s</code> option.

	To pass the required option from libvirt down to Qemu, one can use an additional namespace to pass along options to Qemu as ~~descripted~~ [http://wiki.libvirt.org/page/QEMUSwitchToLibvirt#-s in the libvirt wiki].		To pass the required option from libvirt down to Qemu, one can use an additional namespace to pass along options to Qemu as described [http://wiki.libvirt.org/page/QEMUSwitchToLibvirt#-s in the libvirt wiki].

	Simply replace at the beginning of the XML (for example when editing using <code>virsh edit</code>):		Simply replace at the beginning of the XML (for example when editing using <code>virsh edit</code>):
Line 19:		Line 19:
	and then start the VM.		and then start the VM.

	The GDB session ~~then looks like this~~:		The [https://www.gnu.org/software/gdb/ GDB] session to attach to the process and continue to run it until you hit a bug:

	<pre>		<pre>

Tiziano at 14:07, 5 June 2014

2014-06-05T14:07:51Z

← Older revision		Revision as of 16:07, 5 June 2014
Line 18:		Line 18:

	and then start the VM.		and then start the VM.

			The GDB session then looks like this:

			<pre>
			~ # gdb
			GNU gdb (Gentoo 7.6.2 p1) 7.6.2
			Copyright (C) 2013 Free Software Foundation, Inc.
			License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
			This is free software: you are free to change and redistribute it.
			There is NO WARRANTY, to the extent permitted by law. Type "show copying"
			and "show warranty" for details.
			This GDB was configured as "x86_64-pc-linux-gnu".
			For bug reporting instructions, please see:
			<http://bugs.gentoo.org/>.
			(gdb) file /usr/bin/qemu-system-
			/usr/bin/qemu-system-: No such file or directory.
			(gdb) file /usr/bin/qemu-system-x86_64
			Reading symbols from /usr/bin/qemu-system-x86_64...Reading symbols from /usr/lib64/debug/usr/bin/qemu-system-x86_64.debug...done.
			done.
			(gdb) target remote localhost:1234
			Remote debugging using localhost:1234
			Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib64/debug/lib64/ld-2.17.so.debug...(no debugging symbols found)...done.
			(no debugging symbols found)...done.
			Loaded symbols for /lib64/ld-linux-x86-64.so.2
			0xfffff8003d7ab25f in _start () from /lib64/ld-linux-x86-64.so.2
			(gdb) c
			Continuing.
			</pre>

	[[Category:Snippets]]		[[Category:Snippets]]

Tiziano: Created page with "Sometimes you must be able to analyse Qemu more in-depth than the log files allow to. For this, one can attach a `gdb` instance to a running Qemu process if it is ..."

2014-06-05T14:03:40Z

Created page with "Sometimes you must be able to analyse Qemu more in-depth than the log files allow to. For this, one can attach a <code>gdb</code> instance to a running Qemu process if it is ..."

New page

Sometimes you must be able to analyse Qemu more in-depth than the log files allow to.

For this, one can attach a <code>gdb</code> instance to a running Qemu process if it is started with the <code>-s</code> option.

To pass the required option from libvirt down to Qemu, one can use an additional namespace to pass along options to Qemu as descripted [http://wiki.libvirt.org/page/QEMUSwitchToLibvirt#-s in the libvirt wiki].

Simply replace at the beginning of the XML (for example when editing using <code>virsh edit</code>):

<source lang='xml'>
<domain type='kvm'>
</source>

by
<source lang='xml'>
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
<qemu:commandline><qemu:arg value='-s'/></qemu:commandline>
</source>

and then start the VM.

[[Category:Snippets]]

Debugging Qemu - Revision history

Tiziano: /* Generate core dumps */

Tiziano at 13:15, 12 June 2014

Tiziano at 14:14, 5 June 2014

Tiziano at 14:07, 5 June 2014

Tiziano: Created page with "Sometimes you must be able to analyse Qemu more in-depth than the log files allow to. For this, one can attach a gdb instance to a running Qemu process if it is ..."

Tiziano: Created page with "Sometimes you must be able to analyse Qemu more in-depth than the log files allow to. For this, one can attach a `gdb` instance to a running Qemu process if it is ..."