I did see that in setup.c, there that hypercall to setup callbacks like hypervisor_callback, but when xen will issue the callback? Everytime a domain issues a hypervisor call, xen will issue the callback function? Also, I noticed that hypervisor_callback() will in turn call evtchn_do_upcall, which seems to convert the pending flags to the correspond virq and does doIRQ() to emulating irq injection. Is that right? Thanks for your help. Xin ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://productguide.itmanagersjournal.com/ _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel