Event Channels简要介绍

一.What is upcall
 

  This is typically supportedthrough the use of a registered callback function registered eitherdirectly by the user, or indirectly through the mechanisms of theframework.

二.How to use it
  1.Binding the channel to an eventsource(pIRQ，pIRQ，interdomain，IPI)
  2.Configure a handler for the event.

三.示例
  1.One of the first event channels that a kernelneeds to bind is thetimervirtual interrupt.
  2.The other kind of event that is commonlyrequested is the interdomain event.This is used for delivery of events between the two halvesof split drivers.
  3.not all events of this nature need to bebound; the event channels used forconsole and the XenStore arebound by the domain builder.

四.为什么需要Bind to VCPU
  绑定的含义就是让该VCPU来处理该Event。
  interdomain events are bound to VCPU 0 when theyare created, but can later be rebound to another VCPU.
 每个事件通道(不管是pIRQ,vIRQ,还是Interdomain）都会绑定到特定的VCPU，一般就是VCPU[0]。

五.HVM怎么使用event channel
  HVM也有自己的shared infopage。PV驱动能认识它们，PV也必须使用它们才能和后端驱动通信。

六.Event和Scheduling有什么关系吗
  有一种操作：现在休眠吧，直到有event来临。