Thanks Josepth. I was concerned that buying the new edition would be a simple cover change with errata updates. However, it sounds like enough new material to warrent the purchase. So, off to Amazon... Dave
If an interrupt request takes place before the SYSTICK exception, the SYSTICK exceptionwill preempt the IRQ handler. In this case, the OS should not carry out the context switching.
Otherwise the IRQ handler process will be delayed, and for the Cortex-M3, a usage faultcould be generated if the OS tries to switch to Thread mode when an interrupt is active.
Yes, it if possible to have a mid-priority level SVC so that an OS aware IRQ handler can use the SVC function. But instead of using SVC, you might able to call the SVC function directly rather than using SVC exception.
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