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10.1.2 System Stack Calculation Method
The system stack is most often consumed when an interrupt occurs during service call processing followed by the occur-
rence of multiple interrupts.
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The necessary size (the maximum size) of the system stack can be obtained from the fol-
lowing relation:
Necessary size of the system stack = α
Σβi( γ)
z α
The maximum system stack size among the service calls to be used.
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.
When sta_tsk, ext_tsk, and dly_tsk are used for example, according to the Table 10.1 Stack Sizes Used by Ser-
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ce Calls Issued from Tasks (in bytes),each of system stack size is the following.
Service Call name System Stack Size
sta_tsk 4 bytes
ext_tsk 4 bytes
slp_tsk 4 bytes
dly_tsk 8 bytes
Therefore,the maximum system stack size among the service calls to be used is the 8 bytes of dly_tsk.
z βi
The stack size to be used by the interrupt handler.
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The details will be described later.
z γ
Stack size used by the system clock interrupt handler. This is detailed later.
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After switchover from user stack to system stack
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Refer from Table 10.1 Stack Sizes Used by Service Calls Issued from Tasks (in bytes) to Table 10.3 Stack Sizes Used by Service Calls
Issued from Tasks and Handlers (in bytes) for the system stack size used for each individual service call.
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Kernel interrupt handler (not including the system clock interrupt handler here) and non-kernel interrupt handler.