Hello! I have to simulate some rtos kernel as linux application, just now it works well, but in coroutine mode, where threads switch each other. To simulate switching by hardware timer i need a hook which is called by some linux timer, but exactly on the interrupted stack, not some special stack for signal handlers or timer hooks. I m a newbie in linux, and small experiments shows that usual posix timer signal handler is called not on stack which kernel had interrupted(stack of current thread of my kernel).