ipc- where to send message(ipc).

manish regmi manish_regmi at hotmail.com
Thu May 27 06:49:34 CEST 2004

    i got it. The client need to request tid of the server to name space 
But how much does it slows down a system. For example servers like i/o 
severs and fileservers need to be frequently called.
   Some systems like QNX decreases the no. of message passing by directly 
sending messages to file descriptor(fd) once a file is opened.i.e. directly 
send to i/o manager. will it be good to implement?

>(You were asking both the list and me, so I repeat here)
> > I am new to l4. Is it true that the allocation of tid is given to user. 
>Kind of. As Espen said, the Microkernel provides no name space (except its
>namespaces for kernel resources such as threads, tasks and memory).
>This must be done at user level.
>*One* scheme is to have names ("strings")  for servers, and identify
>servers (their offered services) by these names.  Then servers have to
>register their (string, thread_id) pair at a nameserver, and clients have
>to ask the nameserver for the (string -> thread_id) translation. Of
>course, the nameserver must somehow be found. In the case of DROPS (our
>OS on top of L4), this nameserver is registered at rmgr, and rmgr has a
>fixed and well-known threadid. Thus, name resolution works as follows:
>The client asks the rmgr (threadid 4.0 per definition) for the threadid of
>the nameserver, and then the nameserver for the threadid of the target
>server. The rmgr does not have the flexibility we need for dynamic name
>registering, therefore the nameserver.
>*Other* policies could for instance be one hierarchical namespace,
>resolved by a root nameserver and client nameservers. The root nameserver
>(and the client nameservers) could provide mounting other namespaces. This
>way one could construct a namespace comparable to the UNIX filesystem
>namespace. Drivers could per definition be found under a name like
>'/dev/*'. A user-land file system could provide the part of the namespace
>for /home/, another for /proc/, and another for /usr/.
>You should watch our seminar page, in a couple of weeks some slides about
>namespace issues should show up.

Help STOP SPAM with the new MSN 8 and get 2 months FREE*  

More information about the l4-hackers mailing list