On 26/02/2022 00:41, Kinsey Moore wrote:
This may also be an issue for ARM, RISC-V and others as it doesn't appear that ARM saves CPSR during context switch and I couldn't tell that RISC-V does this either, though I'm less familiar with it.

This doesn't look like the right way to fix this issue.

There is currently the assumption that all processors start multitasking with a context switch to _Thread_Handler() which sets the interrupt level. It is possible to construct a scenario in which we start multitasking with a migration of a thread which already executed the _Thread_Handler() prologue. This would result in an execution with disabled interrupts. I think the proper fix for this scenario is to enable interrupts in _CPU_SMP_Prepare_start_multitasking().

Doing a context switch with interrupts disabled is a fatal application error on all architectures with

#define CPU_ENABLE_ROBUST_THREAD_DISPATCH TRUE

or enabled SMP support.

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