IPC from L4Linux

Bjoern Doebel doebel at os.inf.tu-dresden.de
Thu Nov 2 11:22:32 CET 2006

Hash: SHA1

Daniel Vandersee wrote:
> Adam Lackorzynski wrote:
>> On Fri Oct 27, 2006 at 11:43:40 +0200, Daniel Vandersee wrote:
>>>>>> when I place an ipc call from a l4linux task to an l4 server, I always
>>>>>> get a task number, which, I think, is not assigned. Is for every l4linux
>>>>>> task a new l4 task is generated/reserved?
>>>> Yes. Every L4Linux process is run in a separate L4 task, Linux system calls
>>>> are reflected to the L4Linux server.
>>> Is it possible to determine the task number of the parent process
>>> anyhow? Or is it possible to get a list of subprocesses L4Linux has created?
>> Not without coding something.
> Could you get more specific, please? Does it mean I have to write (or at
> least to modify) a task server which allows me to determine the
> hierarchy? 

This is one solution. Another would be to let your Linux task register
their L4 Thread ID at some server that stores the PID->L4ID mapping. To aid
you, we could need some more information about what exactly you are trying
to do. ;)

> What if an application uses l4_task_new to create a new task
> instead of using a task server? In this case I can't figure out the
> parent task, can I?

Only the chief of a new task can start it using l4_task_new(). At the child
you can find out who your chief is by calling l4_nchief(l4_myself(), &chief).

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