Hello, Sometime i lose my i/o privilege put with the system call ioperm (in the main function of my program). My application stop with a "killed" message in the console and in /proc/xenomai/fault i've an "general fault". To ignore this problem, i use the call system iopl (with full privilege) or recall ioperm before each inb or outb. But there is a problem, why i/o privilege are losted ? In attachment you can find an archive with an example (application and source) witch show the problem. This program has 2 task : - task_1 priority 23 period 100 ms, lock a mutex, access to /dev/rtc, unlock the mutex, outb on hardware. - task 2 priority 25 period 1 ms, do nothing ! I put a 1 ms period to task_2 because it's near the speedest period on my cpu (166 MHz). With this period it stop immediatly. If i put 10 ms it's need 1 or 2 minutes. On my Pentium 4 (Ubuntu on VmWare worstation under WindowsXP), i put 30 ms (the more speed before overrun). If i use iopl (and not ioperm), no problem. If i just have task_1, no problem. If i don't use mutex (lock for Rtc access) on task_2, no problem. I use Xenomai Xenomai 2.3-rc2 (adeos 1.5-02), same probleme with 2.2.3. If you have an idea. thanks nicolas blanchard