Re: FYI: SIM

Hi dexter, thanks for your update! On Tue, Mar 09, 2010 at 03:12:47PM +0100, dexter wrote: yes, if you think about a synchronous / "blocking I/O" scenario. However, you could always have something asynchronous: The caller calls something like sim_card_transceive(*message, *cb), and the driver calls back the 'cb' function when it has received the data. I think the latter is the best we can do at the moment. Another possible concept is to introduce some kind of message queue: The entity that wants to issue a command to the SIM sends a message into the queue, indicating to which other message queue any responses shall be queued to. I agree the synchronous approach seems to be the more natural one (for most human beings at least). However, it comes at the cost of scheduling overhead/latency, new possibilities for deadlocks and potentially difficult debugging than in a single-threaded program. Right now I don't really know yet how many threads/tasks we will end up having. I only know we should be careful and not to have too many of them. Layer2 is certainly going to be one task, Layer3 will have at least one. Layer3 is he entity that normally talks to the SIM, at least excluding things coming directly from the app like phonebook access and storing SMS. If the caller does not care, he could simply specify a NULL pointer as *response. -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)