Configuration of Non-Functional Properties in Embedded Operating Systems · · tion models. Hence, the clock cycles remain constant. The ActivateTask() system call, however, modifies kernel structures. No memory protection does not involve any overhead, whereas the semi-trusted variant needs 43­24=19 extra clock cycles to reprogram the MPU to allow write access to kernel space and disallow it after the call. A full trap with switch to supervisor mode and back to user mode costs 86­24=62 addi- tional cycles. The kernel-internal dispatch() function switches the protection domain from one application to another in both protected modes, leading to a cost of 148­88=60 cy- cles. Since this function is invoked inside the kernel, there is no difference between the semi-trusted and the standard protected mode. a broad range of related work, which is discussed in the following. Non-Functional Properties and Software Product Lines Siegmund et al. propose the use of a semi- automated derivation (SAD) to assist develop- ers in selecting product features in SPLs with a large number of features (Siegmund et al., 2008, Rosenmüller et al., 2008). The basic idea is to hide variation points that are irrelevant due to non- functional requirements that should be met. They claim that traditional approaches do not consider non-functional properties or alternatives for a fea- ture implementation. To solve this problem, they present an integrated software product line model (ISPLM), which integrates code units and their non-functional properties into the feature model. (Benavides et al., 2005) propose an extension