On 06/29/2012 03:47 PM, Daniel Veillard wrote:
On Fri, Jun 29, 2012 at 03:07:54PM +0800, Dennis Chen wrote:
virsh talks to the libvirtd daemon, the libvirtd daemon run those calls from the qemu driver. The documentation is relatively sparse, but reading what is available will help:
http://libvirt.org/api.html http://libvirt.org/internals.html
so if you want to step though that function you must gdb the libvirt daemon, not the client application.
Daniel en, this Daniel is not that Daniel: ) I remember that I joined the
On 06/29/2012 02:49 PM, Daniel Veillard wrote: [...] presentation about libvirt delivered by you in Nanjing University last year. ah yes, there is Dan and Daniel that can be a bit confusing :-)
Yes, the document about libvirt is sparse, so I am often confused when I try to understand the internals of the relationship between QEMU, KVM and libvirt... ah, yes the overall stack is a bit complex.
Let me go through the link you mentioned to see if I can understand libvirtd comes from and the relationship with libvirt... Basically for some driver the application talk to the libvirt daemon to implement all the entry points of a driver (qemu/lxc for example), it uses the remote driver to connect to the daemon, and the daemon calls the real driver. Sometimes, the driver in the applcation does the work by talking directly to the hypervisor (ESX/Hyper-V). So if you want to debug/gdb the qemu code you must attach to libvirtd daemon not to the application. See slide 5 of the CLK slides ;-) http://veillard.com/Talks/CLKLinux2011.pdf
Daniel
Actually I've downloaded your ppt from http://v.csdn.hudong.com/linuxkernal2011/page2.html, slide 5 and 12 is useful for me because it's a overview picture. About daemon, in my system: root@dennis-:/home/dennis/workspace/Software# ps aux | grep libvirtd root 20308 0.0 0.1 102908 3540 ? Sl 15:25 0:00 /usr/sbin/libvirtd -d so the libvirtd daemon is there, but I have questions about this daemon: 1. where is the daemon source code, it's in the libvirt tar package? 2. Who is responsible to start this daemon and when? BRs, Dennis