How to debug Libvirt problems

Identifying your problem area
Something that ensures that the component in question is at fault not xen qemu virt-*? #TODO FIXME...

All bug reports
In all cases, the following should be mentioned and attached to your bug report:

service libvirtd start rpm -q libvirt smoltSendProfile -a | grep public uname -r /var/log/xen /var/log/libvirt/qemu /etc/libvirt/libvirtd.conf /etc/libvirt/qemu.conf /var/log/libvirt/libvirtd.log
 * The exact command-line used to start libvirt if other than.
 * The version number of libvirt.
 * The output url from smolt.
 * The kernel your using.
 * The name of the hypervisor (Xen, QEMU, KVM) your using.
 * The XML config of the guest domain
 * If using Xen hypervisor, the XenD logfile.
 * If using QEMU/KVM, the domain logfile
 * If altered the libvirtd.conf file
 * If altered the qemu.conf file
 * Libvirt log file with debug logging enabled.

Debugging Libvirt
As root install libvirt debug package.


 * 1) debuginfo-install libvirt

Find libvirtd process ID ( PID )

Sample output...

$ ps -C libvirtd PID TTY         TIME CMD 3983 ?       00:00:00 libvirtd

Attache GNU Project Debugger to libvirt PID

$ gdb libvirtd 3983

If gdb complaints about "Missing separate debuginfos" then type "quit" in the gdb shell and do a copy paste of the debuginfo-install entry and install it the same way as above then and rerun the gdb libvirtd PID command.

Sample error entry... Missing separate debuginfos, use: debuginfo-install

Enable logging to a file in gdb.

From the gdb shell type `set logging on'

Sample ouput...

(gdb) set logging on Copying output to gdb.txt. Current language: auto; currently minimal

Then type cont and redo the steps in libvirt that caused the error your experiencing.

Sample output...

(gdb) cont Continuing.

After you have recreated the steps that causes the error your experiencing press CTRL-C in the gdb shell and type thread apply all bt.

Sample output... ^C Program received signal SIGINT, Interrupt. 0x0000003846ad50d3 in *__GI___poll (fds=, nfds= , timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87 87	 int result = INLINE_SYSCALL (poll, 3, CHECK_N (fds, nfds), nfds, timeout); Current language: auto; currently minimal (gdb) thread apply all bt

Thread 19 (Thread 0x7fffdacff910 (LWP 20935)): Output trunkated....

---Type to continue, or q to quit--

Press return until you are returned to the gdb shell then type quit and exit the debugger.

Sample output...

Current language: auto; currently minimal (gdb) quit The program is running. Quit anyway (and kill it)? (y or n) y

Attach gdb.txt to your bugzilla report..

If the application crashes on startup you need to start it inside the GNU Project Debugger to do so type open an terminal window and type gdb.

Sample output...

[username@example ~]$ gdb GNU gdb (GDB) Fedora (6.8.50.20090302-38.fc11) Copyright (C) 2009 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later  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-redhat-linux-gnu". For bug reporting instructions, please see: . (gdb)

First we want to turn on logging then execute startup of the application and finally tell it to run at our command.

Sample output for...

(gdb) set logging on Copying output to gdb.txt. (gdb) exec-file /usr/sbin/libvirtd (gdb) run Starting program: /usr/sbin/libvirtd

When the application has crashed type thread apply all bt and quit gdb.

Sample output...

gdb) thread apply all bt

Thread 19 (Thread 0x7fffdacff910 (LWP 20935)): Output trunkated....

---Type to continue, or q to quit--

Press return until you are returned to the gdb shell then type quit and exit the debugger.

Sample output...

Current language: auto; currently minimal (gdb) quit The program is running. Quit anyway (and kill it)? (y or n) y

Attach the gdb.txt to your report