miscdevice共享一个主设备号MISC_MAJOR（即10），但次设备号不同。所有的miscdevice设备形成一个链表，对设备访问时内核 根据次设备号查找。-Miscdevice share a major number MISC_MAJOR (10), but the device number is different. All miscdevice equipment to form a linked list, access to equipment when the kerne