CompuLab SBC-X270 Manual de usuario descargar pdf (Pagina 36)

SCIOPTA - Real-Time Kernel

4-2 Manual Version 4.1 User’s Manual

SCIOPTA - Real-Time Kernel

4 Modules

4.5 System Protection

In bigger systems it is often necessary to protect certain system areas to be accesses by others. In SCIOPTA the

user can achieve such protection by grouping processes into modules creating sub-systems which can be protected.

Full protection is achieved if memory segments are isolated by a hardware Memory Management Unit (MMU). In

SCIOPTA such protected memory segments would be laid down at module boundaries.

System protection and MMU support is optional in SCIOPTA and should only be used and configured if you need

this feature.

4.6 SCIOPTA Module Friend Concept

SCIOPTA supports also the “friend” concept. Modules can be “friends” of other modules. This has mainly conse-

quences on whether message will be copied or not at message passing. Please consult chapter 6.9 “Messages and

Modules” on page 6-8 for more information.

A module can be declared as friend by the sc_moduleFriendAdd system call. The friendship is only in one direc-

tion. If module A declares module B as a friend, module A is not automatically also friend of Module B. Module

B would also need to declare Module A as friend by the sc_moduleFriendAdd system call.

Each module maintains a 128 bit wide bit field for the declared friends. For each friend a bit is set which corre-

sponds to its module ID.

1 2 ... 31 32 33 34 35 36 37 38 39 40 41 ... 225 226

CompuLab SBC-X270 Manual de usuario Pagina 36