系统调用 将字符串参数name的内容拷贝到内核中保存下来 将内核中由iam()保存的名字拷贝到name指向的用户地址空间中，同时确保不会对name越界访存-System call will copy the contents of the string parameter name into the kernel by the kernel to survive iam () to save a copy to the name point to the name of the user address space, at the same time ensure that no cross-border visit to keep name