Re:Re: Another question about L4 system call

To hal: Thank you, I am blush for making such a stupid mistake.

To Raphael:  
Thank you for your  so clearly explanations. Now i am clearly with it.
In addition, do your "trampolines in the KIP" means the user_syscall(eg..user_Ipc()) in file /kernel/src/glue/v4-ia32/user.cc ? 
>From the page table's view, the code in that file is protected . Only in system level can be accessed.
Because it's a part of the kernel. 
when funtion user_ipc() is called from user space (the __L4_Ipc() ). The CPU is still in user mode.
Not enter system mode yet, so it can't access the address protected  by the page table, such as the user_ipc()'s address.   I am puzzleed about these.

Thank you ,all !

Best Regards
Bob