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6.1. Memory Management
Open Meta Metamodel
instantiates
Open Metamodel
instantiates
instantiates
instantiates
Open Model
(verified and validated)
Model 1
Model 2
Model 3
generates
instantiates
instantiates
Open Source
(verified and validated)
Model Implementation 1
comunicates
Supplier Implementation 1
instantiates
comunicates
compromises
comunicates
compromises
Supplier Implementation 2
(malicious)
Figure 6.2.: Possible spoiling with open models
6.1. Memory Management
The security problem with third-party implementations in an open model concept cannot be
completely avoided, but its influence to other components should be minimised. Because this
problem is not very uncommon, there exist different strategies for keeping the security of the
rest of the system uninfluenced from a faulty and malicious component.
There are different ways on how a component can influence another, but the access of the
used memory / data is the most problematic one. This means if a component can read and
write to the memory of another component it can change the data used for execution or even
the execution itself. Therefore, the following different memory management strategies are
described that reduce or avoid this problem in multiprocessing systems.
6.1.1. Partitioning
Partitioning means that the main memory of multiprocessing operating systems is divided
in sequential partitions. Programs or processes can only be loaded and executed in such a
partition and can only access the memory of their partition. Partitioning can generally be
divided in:
Static partitioning: The memory M is divided in n = const fixed sized partitions p i , ∀i :
length(p i ) = const, M = {p 0 , p 1 , . . . , p n } while length(M) ≥ ∑ n
i=0 length(p i) [77,
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