about synchroniztion of migration

[tgh <wwwwww4187@sina.com.cn>]

hi

I have read your ppt on xen summit,and i try to read the migration
code,but have some confusions

In your ppt it has been pointed out that:
1)Many synchronous forks for external device migration (4 stages for
each attached device)
2)Xenstore callbacks from host to guest and back to initiate final
round, and from bridge to checkpoint daemon

I try to read the code ,and find the synchronization between hostOS and
guestOS,and between the XC_SAVE and saveInputHandler,but where is
synchronization between the bridge to the checkpoint daemon, and how
does the device migration do synchronization, i have read the code of XC_SAVE and 
device migrate,and find the step1,3,4, but i could not find out how does the synchronization work,could you give
me some detailed expalanation about it ,or where the code are ?

another question is about how does the network transfered from sources to destination? that is ,where is the code,and how is it invoked?

Thanks