Hi there, I'm working on two applications which require communication over shared memory.
Therefore, I've adapted some of your datastructures (such as the slab allocator, semaphores and locks) so that they are safe to be shared between different address spaces, by adding smart pointers and taking care of having all shared components (like the Applicant list of the locks, the applicants and the locks themselves) within the shared memory. I have now a little problem with the locks. I have a thread in address space 1 which performs a lock operation on a lock in shared memory. The lock operation is (by default) mapped to the L4_Stop syscall (I work with the Okl4-Kernel). Another thread in address space 2 performs a wake-operation on the same lock (where the thread id is deposited in the applicant), which is mapped to L4_ThreadSwitch which is again mapped to the L4_ExchangeRegisters syscall. This operation does not wake the first thread. In detail, the L4_ThreadWasHalted call which is performed upon L4_ThreadSwitch returns false, hence the thread which tried the wake operation remains spinning in the forever-loop (this is a nice opportunity for a denial-of-service-attac of a malicious client by the way...). However, I've started to investigate by replacing the L4_ThreadSwitch syscall by L4_WaitNotify and the wake-operation by L4_Notify. The result was the same. Checking the error code of the L4_Notify syscall with L4_ErrorCode showed that the call had been aborted due to L4_ErrInvalidThread, respectively L4_ErrNonExist (2). Now I wonder if a thread is generally allowed to invoke syscalls on threads which don't belong to its address space (maybe I need some capability? What exactly is env()->pd_session()->bind_thread() for?). I've also noticed that the thread ids I get from env()->cpu_session()->state() or from thread_get_my_native_id() differ from those the kernel debugger shows (what exactly do you do when you ask Okl4::__L4_TCR_ThreadWord(Genode::UTCB_TCR_THREAD_WORD_MYSELF) for a thread id? Is that the global thread id?) Perhaps you have an idea what's going wrong here (meanwhile I'd add L4_MutexControl to core :o) ). With kind regards Sven -- Sven Fülster ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Genode-main mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/genode-main
