Zilog EZ80F91AZA User Manual
Page 34
UM007518-1211
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Zilog Real-Time Kernel: eZ80
®
CPU
User Manual
Q:
When I post a message to a higher-priority thread from an ISR, the context switch
does not occur immediately. Why is that?
A:
RZK follows the priorities below, in descending order, for executing components:
ISR
Interrupt Thread
User Priority Threads
Execution is always transferred to the ISR, because it holds the highest priority. Thus, con-
text switching does not occur even when messages are posted to higher-priority threads
from an ISR that runs from the context of a lower-priority thread. Context switching
occurs only when all of the current pending interrupts are serviced.
Q:
What happens when I specify zero wait time in calls such as
RZKAcquireSema-
phore
or
RZKReceiveFromQueue
?
A:
When zero wait time is specified in these calls, they become non-blocking calls and
return immediately.
Q:
Is
RZKCreateSemaphore
with zero initial count value supported by RZK?
A:
Yes, this feature is supported by RZK.
Q:
When an RZK thread is deleted does it also release all of the resources created during
its execution?
A:
No. RZK does not release any of the resources created when that thread is deleted. But
you can achieve the same functionality by deleting the unwanted resources in the cleanup
functions, which will be executed during the thread deletion.
Q:
Does RZK support the Priority Inheritance protocol?
A:
Yes. RZK supports Priority Inheritance protocol. For more information about how to
choose the option, refer to the
,
which is available free for download from zilog.com and also located in the following
path:
Files\Zilog\ZDSII_eZ80Acclaim!_A.B.C\ZTP\ZTPX.Y.Z_Lib\RZK\Docs
Q:
Does the Priority Inheritance protocol take care of both unbounded and bounded pri-
ority inversion?
A:
Yes, it does. RZK supports priority inheritance for both unbounded and bounded pri-
ority inversion.