Ericsson RBS 2106 Reference Manual page 372

Self Test and Supervision
46.4.3 Supervision of Application Program
Purpose
Supervises the application software. If the execution of the software
fails (for example a cyclic loop) the function exception processing
interrupts the execution.
Preconditions and Initiation
Initiates automatically at start of application software.
Description
The main processor supervises the operation of the sub-processors by
the regular reception of signals from the sub-processors. When no
normal operation signals are generated dummy signals will be generated
instead. Dummy signals generated from a subprocessor, tell the main
processor that the sub processor is still in an operational state.
The main processor receives exceptions from a number of sources such
as arithmetic overflows, I/O interrupts, system calls and when no
operational or dummy signals from the sub-processors are generated.
When the processor detects one of these exceptions it disables interrupts
and forces execution of a software exception processor (called the
handler) located at a fixed address. The handler saves the contents of
the processor, including the context of the program counter, the current
operating mode (user or supervisor) and the status of the interrupts
(enabled or disabled). These contents are saved so it can be restored
when the execution has been serviced. When an exception occurs, the
CPU loads the Exception Program Counter (EPC) register with a
location where execution can restart after the exception has been
serviced.
46.4.4 Supervision of DMRU Loadfiles
Purpose
The function investigates that loadfiles are correctly stored in CMRU
memory.
Preconditions and Initiation
The CMRU application software is loaded and activated. The function
is then activated when the CMRU detects loadfiles in the DMRU that
are expected in the CMRUs non-volatile memory. These are then
transferred from the DMRU to the CMRU.
Description
The loadfiles in the non-volatile memory of the CMRU are supervised
by continuous comparison of checksum. Detected errors are reported to
the function Diagnostics and Fault Handling. The checksum comparison
on each supervised loadfiles is performed with 5–minute intervals. This
supervising function has low system priority and is performed as a
background activity.
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EN/LZT 720 0008 P2A
2001-11-28