TMS320C645x DSP Serial RapidIO User's Guide中说：“A processing element that receives a doorbell transaction takes the packet and puts it in a doorbell message queue within the processing element.This queue may be implemented in hardware or in local memory. This behavior is similar to that of typical message passing mailbox hardware.”。但是这个“ doorbell message queue”到底在哪里，是指哪个寄存器啊？我翻遍了手册也没有找到这个队列，求指点一下~~谢谢
