direct IPC VS Short IPC

hazwan kogee.san at
Mon Mar 24 10:16:32 CET 2008


I have problems in understanding short ipc and direct long IPC. Just want to
know that is it implementing register short IPC with direct long IPC
implementation is the same. Unlike indirect long IPC, we must use the
message header (strdope, send dope and size dope) . Do i must also use the
message structure for implementing direct long ipc or i just use the same
implementation on short register message (L4_IPC_SHORT_MSG)? Im kinda
confuse and unsure of this issue due to unproper theory understanding. Like
indirect IPC, i can understand that the memory that saves the message is
only being reffered by both threads that wish to communicate by referring
the memory address of the message. Unlike direct long IPC message, what I do
understand is that each thread has a copy of the message at the threads
respective user space. However, I dont know how to copy the message from one
thread user space to the other threads user space using IPC call. But if the
implementation of the direct long IPC is as the same as the register
message(L4_IPC_SHORT_MSG), then i think I can imagine the flow. Thank you
and your help is highly appreciated.
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