Agilex™ 5 ES Device Errata and User Guidelines

ID 825514
Date 12/09/2024
Public
Document Table of Contents

3.2.14. 2141647: A64 WFI or A64 WFE executed in Debug state suspends execution indefinitely

Description

Executing an A64 WFI or WFE instruction while in Debug state results in suspension of execution, and execution cannot be resumed by the normal WFI or WFE wake-up events while in Debug state.

Conditions

  1. The Processing Element (PE) is in Debug state and in AArch64 Execution state.
  2. A WFI or WFE instruction is executed from EDITR.

Impact

If the above conditions are met, the PE will suspend execution.

This is not thought to be a serious erratum, because an attempt to execute a WFI or WFE instruction while in Debug state is not expected.

For WFI executed in Debug state, execution can only resume by any of the following:

  • A Cold or Warm reset
  • A Restart request trigger event from the Cross Trigger Interface (CTI) causing exit from Debug state, followed by a WFI wake-up event

For WFE executed in Debug state, execution can only resume by any of the following:

  • A Cold or Warm reset
  • A Restart request trigger event from the CTI causing exit from Debug state, followed by a WFE wake-up event
  • An external event that sets the Event Register. Examples include executing an SEV instruction on another PE in the system or an event triggered by the Generic Timer.

Workaround

A workaround is unnecessary, because an attempt to execute a WFI or WFE instruction while in Debug state is not expected.

Category

Category C